Impact of age on surgical outcomes for World Federation of Neurosurgical Societies grade I and II aneurysmal subarachnoid haemorrhage: a novel prognostic model using recursive partitioning analysis

Impact of age on surgical outcomes for World Federation of Neurosurgical Societies grade I and II aneurysmal subarachnoid haemorrhage: a novel prognostic model using recursive partitioning analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impact of age on surgical outcomes for World Federation of Neurosurgical Societies grade I and II aneurysmal subarachnoid haemorrhage: a novel prognostic model using recursive partitioning analysis Motoyuki Umekawa, Gakushi Yoshikawa This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4922161/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Oct, 2024 Read the published version in Neurosurgical Review → Version 1 posted 11 You are reading this latest preprint version Abstract Objective This study aimed to evaluate age as a prognostic factor and develop a comprehensive prognostic model for patients undergoing clipping surgery for World Federation of Neurosurgical Societies (WFNS) grade I/II aneurysmal subarachnoid haemorrhage (SAH). Methods We retrospectively investigated 188 patients with WFNS grade I/II SAH who underwent microsurgical clipping at our institute between December 2010 and January 2020. The data of 176 patients (75 with grade I and 101 with grade II) were analysed. Data on patient demographics, aneurysm characteristics, SAH factors, surgical details, and clinical outcomes were collected. Prognostic factors were assessed using bivariate and multivariable logistic regression analyses, and recursive partitioning analysis. Results Favourable outcomes (mRS 0–2) were observed in 76% of patients. Age, a significant negative prognostic factor in multivariable analysis (odds ratio 0.55, 95% confidence interval 0.40–0.76, p 70 years (84% vs. 46%, respectively; p < 0.001). Epileptic seizures were significantly associated with poor outcomes in older adults (p < 0.001). A prognostic model (favourable, intermediate, and poor) based on age and postoperative adverse events showed significantly different outcomes between age groups (p < 0.001). Conclusions Age was a stronger prognostic factor than WFNS grading for patients with grade I/II SAH undergoing microsurgical clipping. For patients aged ≤ 70 years, precise microsurgeries with fewer complications were associated with favourable outcomes beyond WFNS grade. For older patients, postoperative intensive seizure management may prevent poor outcomes. aneurysm age-dependent microsurgical clipping recursive partitioning analysis subarachnoid haemorrhage World Federation of Neurosurgical Societies grade Figures Figure 1 Introduction Subarachnoid haemorrhage (SAH) has an incidence of 1–20 cases per 100,000 population, with approximately 85% of cases caused by ruptured aneurysms [21,28]. Rerupture of aneurysms leading to SAH has a mortality rate of 50–60%. Therefore, surgical intervention to prevent rerupture is the primary step for SAH treatment [15,18,33]. Treatment approaches can be broadly divided into microsurgery, such as clipping or trapping with bypass, and endovascular treatments, primarily coiling [16,24,26]. The frequency of clipping for SAH has decreased with advances in endovascular devices [17,37], but the rate of recurrence of aneurysms after clipping is lower than that after coiling [2,5,9,40]. Therefore, our institution actively performs microsurgical clipping for aneurysmal SAH from a curative standpoint. However, less invasive endovascular treatments may be selected for older adults or those with poor surgical tolerance, depending on their general condition. The World Federation of Neurosurgical Societies (WFNS) classification evaluates severity based on the level of consciousness and the presence of neurological symptoms and is widely used as the gold standard due to its correlation with prognosis [34]. While low-grade SAH (WFNS grade I and II) generally has a better prognosis than higher-grade SAH (WFNS grade III-V), outcomes are not always favourable due to factors such as patient background, surgical complications, and adverse events arising from the management of vasospasm or systemic complications [3,7,10,20,22,30,35,44]. Although various factors influencing prognosis in low-grade SAH have been examined, the evidence remains insufficient. The age at onset has been reported as a prognostic factor for SAH and is simple to evaluate [4,6,23,31,42]. However, few studies have investigated the effects of age on low-grade SAH outcomes. Hence, in this study, we aimed to explore the prognostic factors of patients who underwent microsurgical clipping for WFNS grade I and II SAH and develop a simple prognostic model mainly based on patient age of onset. Methods Participant selection We collected data on patients who developed SAH from ruptured cerebral aneurysms (including dissecting aneurysms) between December 2010 and January 2020 and underwent open surgery, using an institutional SAH database. Patients whose modified Rankin scores (mRS) were ≥3 were excluded. Data regarding patient-, aneurysm-, SAH-, and surgery-related factors and clinical outcomes that were prospectively collected and recorded in the database were retrospectively evaluated. Informed consent was obtained from all participants, and the study was approved by the Institutional Ethics Committee of Showa General Hospital (approval number REC-328). Procedures and techniques of SAH management The treatment protocol for low-grade SAH via microsurgical clipping at our institution was as follows: Initially, digital subtraction angiography (DSA) was performed under sedation and analgesia to determine the treatment strategy. If patients visited within three days of SAH onset, surgery was performed on the same day or the following day. For patients arriving after the fourth day of onset, the timing of surgery depends on the initial DSA findings of vasospasm and the patient's general condition. Ventricular and cisternal or lumbar drainage is employed postoperatively for ventriculo-cisternal irrigation and intracranial pressure control therapy. Postoperative management of SAH has been described in detail in previous studies [36]. Imaging evaluation primarily involved CT scans to assess SAH distribution until day 3. On day 4, an MRI is performed to evaluate early ischaemic lesions and vascular conditions before the vasospasm. On day 7, DSA was performed to detect cerebral vasospasm and aneurysms. MRI is repeated on day 14 to detect late-stage vasospasms and ischaemic lesions. Additionally, shunt surgery was performed if symptomatic post-SAH hydrocephalus occurred, and appropriate general medical treatment was performed if needed throughout the time course. Treatment outcomes and statistical analyses The median and interquartile ranges (IQR) were calculated for each factor. The primary outcome was the mRS at discharge, with a favourable outcome defined as mRS 0–2. The following complications were assessed in the safety evaluation: emergent additional surgery, vasospasm, delayed cerebral infarction (DCI), epileptic seizures, secondary hydrocephalus (shunt placement excluded from additional surgery), meningitis, and systemic medical complications. Vasospasm was defined as any angiographical vasospasm detected by DSA or magnetic resonance angiography (MRA) with a decrease of ≥50% in the cerebral artery diameter relative to the preoperative value. This was judged solely on radiological findings, regardless of symptoms [10]. DCI was defined as symptomatic infarction identified on CT or MRI after excluding surgery-related infarction with any angiographical vasospasm [39]. To create a prognostic model for favourable outcomes, bivariate and multivariable logistic regression analyses were performed for the patient background factors, including age and WFNS grade, SAH factors, and surgical factors. Factors showing significance in the bivariate analysis were included in the multivariable analysis along with age and WFNS grade. Further analysis using factors related to postoperative adverse events was conducted to assess their association with favourable outcomes. In this analysis, factors for multivariable analysis were selected using a stepwise forward selection method with a P-value threshold of <0.10. A cutoff value for age as a continuous variable was calculated from the receiver operating characteristic (ROC) curve using the Youden index, creating a two-group division for age. Finally, recursive partitioning analysis (RPA) used patient background, including dichotomised age and other significant factors from the bivariate analysis, to develop a three-group prognostic model (favourable, intermediate, poor) for favourable outcomes. P-values of <.05 denoted statistical significance. Statistical analyses were performed using JMP Pro 17 software (SAS Institute Inc., Cary, NC, USA). Data Availability The authors confirm that data collected for the study and analysis methods will be shared upon reasonable request from any qualified investigator. Results Participant selection We obtained data on 373 patients who developed SAH due to ruptured cerebral aneurysms (including dissecting aneurysms) between December 2010 and January 2020 and underwent open surgery from an institutional SAH database. Of them, 188 with WFNS grades I and II SAH were identified. After excluding 12 patients whose modified Rankin scores (mRS) were 3 or more, 176 (75 patients with WFNS grade I and 101 with grade II) were included in this study. Participant baseline characteristics and surgery for SAH The median age of the 176 patients with low-grade aneurysmal SAH included in this study was 57 years (IQR, 47–70 years), and females were predominant (68%, Table 1 ). Hypertension was the most common comorbidity (52%), while diabetes mellitus was rare (4%). Fifteen patients (9%) already had mRS scores of 1 or 2 before SAH onset. For 93% of the patients, the aneurysm type was saccular, with the distribution of the aneurysm locations consistent with that of the general population. The pterional approach was the most frequent surgical approach, and bypass was used in 7% of surgeries involving clipping or trapping. Most surgeries were performed on the day of onset or the following day. Table 1 Baseline characteristics of patients with aneurysmal subarachnoid haemorrhage and surgical procedures Number (%)/Median [IQR] Patient factor Age, years 57 [47–70] Female sex 120 (68%) Comorbidities Hypertension 92 (52%) Dyslipidaemia 33 (19%) Diabetes mellitus 7 (4%) History of malignancy 20 (11%) Active smoking 57 (32%) Concomitant unruptured aneurysm 38 (22%) Use of antithrombotic 7 (4%) mRS 1 or 2 before SAH onset 15 (9%) SAH factor WFNS grading I 75 (43%) II 101 (57%) GCS 15 75 (43%) 14 75 (43%) 13 26 (15%) Aneurysm type Saccular 163 (93%) Maximum dome diameter, mm 5.0 [3.9–7.0] Dissecting 13 (7%) Maximum length, mm 6.3 [3.2–9.9] Location of aneurysm Acom 46 (26%) IC-Pcom 44 (25%) MCA 38 (22%) IC-Ach 12 (7%) IC C2 11 (6%) Distal ACA 6 (3%) VA 8 (5%) BA 7 (4%) Other posterior circulation 4 (2%) Fisher group 3 157 (89%) Concomitant ICH 11 (6%) Surgical factor Approach Pterional 143 (81%) Interhemispheric 22 (13%) Suboccipital 11 (6%) Bypass 14 (7%) High-flow bypass 7 (50%) Low-flow bypass 7 (50%) Day of surgery from onset Day 0,1 141 (80%) Day 2–4 22 (13%) Day 5 or later 13 (7%) ACA, anterior cerebral artery; Acom, anterior communicating artery; BA, basilar artery; GCS, Glasgow coma scale; ICH, intracerebral haemorrhage; IC-Pcom, internal carotid artery-posterior communicating artery; IQR, interquartile range; MCA, middle cerebral artery; VA, vertebral artery; WFNS, World Federation of Neurosurgical Societies Variables are indicated as number (%) and median [interquartile range]. Primary outcome and postoperative adverse events At discharge, the mRS score was 0 for 65 (37%), 1 for 30 (17%), 2 for 39 (22%), 3 for 19 (11%), 4 for 19 (11%), 5 for 2 (1%), and 6 for 2 (1%) patients. The overall rate of favourable outcomes was 76%, with 22% of the patients having mRS of 3 or 4 and 2% having mRS of 5 or 6. Among the patients who died, one was an 83-year-old man who experienced postoperative rerupture of a 15-mm internal carotid artery-anterior choroidal artery aneurysm, and his family opted to withdraw from further treatment due to his advanced age. The other patient was a 60-year-old woman undergoing active treatment for breast cancer who experienced severe SAH from a newly ruptured vertebral artery dissecting aneurysm after clipping for an anterior communicating artery aneurysm. All the postoperative adverse events are summarised in Table 2 . Symptomatic cerebral infarction due to surgery occurred in 5% of the patients. Emergent additional surgery for postoperative haemorrhage, cerebral swelling, or aneurysm rerupture was performed for 10 patients (6%). Only 9% of the patients developed DCI, despite 49% having confirmed vasospasm. Epileptic seizures occurred in 21 patients (12%), all of which required antiepileptic drug treatment. Meningitis (requiring extended antibiotic therapy) affected 32 patients (18%). Symptomatic secondary hydrocephalus requiring shunt placement occurred in 43 patients (19%). Pneumonia and electrolyte abnormalities due to cerebral salt-wasting syndrome, diabetes insipidus, and the syndrome of inappropriate antidiuretic hormone secretion were the most common systemic complications. Each occurred in 15 patients (9%) with no associated deaths. Table 2 Details of postoperative and systemic complications after surgery for low-grade SAH Number (%) Postoperative complication Symptomatic infarction by surgery 9 (5%) Oculomotor nerve palsy by surgery 6 (3%) Postoperative rupture 4 (2%) Postoperative additional surgery 10 (6%) Total vasospasm 87 (49%) Delayed cerebral infarction 15 (9%) Epileptic seizure 21 (12%) Meningitis 32 (18%) Secondary hydrocephalus 43 (19%) Systemic complication Pneumonia 15 (9%) CSWS, DI, SIADH 15 (9%) Liver failure/ cholecystitis 13 (7%) Heart failure 9 (5%) Gastrointestinal bleeding 8 (5%) Urinary tract infection 4 (2%) Pulmonary embolisation 2 (1%) CSWS, cerebral salt-wasting syndrome; DI, diabetes insipidus; SIADH, syndrome of inappropriate antidiuretic hormone secretion Values are indicated as number (%). Analyses of favourable outcomes using background factors and adverse events In the bivariate analysis, significant negative correlations with favourable outcomes were found for age (continuous, per increasing decade, odds ratio [OR] 0.51, 95% confidence interval [CI] 0.38–0.69, p < 0.001) and mRS 1 or 2 before SAH onset (OR 0.32, 95% CI 0.11–0.94, p = 0.038). WFNS grade II against grade I did not show statistical significance ( p = 0.083, Table 3 ). In the multivariable analysis, age (per increasing decade, OR 0.55, 95% CI 0.40–0.76, p < 0.001) was the only significant negative factor for favourable outcomes, making it a key result of this study. ROC curve analysis for age and favourable outcomes showed an area under the curve of 0.737, with the age of 70 years having a sensitivity of 0.866, specificity of 0.500, positive predictive value of 0.847, and negative predictive value of 0.538. Patients aged ≤ 70 years had significantly better outcomes than those aged > 70 years (favourable outcome: 84% vs. 46%, respectively; p < 0.001). Table 3 Analysis of baseline factors related to favourable outcomes after surgery for low-grade subarachnoid haemorrhage Bivariate Multivariable OR [95% CI] P -value OR [95% CI] P -value Patient factor Age (continuous, per increasing decade) 0.51 [0.38–0.69] < 0.001 * 0.55 [0.40–0.76] 70 years (vs. ≤70 years) 0.16 [0.07–0.34] 80 years (vs. <65 years) 0.08 [0.02–0.33] 80 years (vs. 65–80 years) 0.23 [0.05–1.00] 0.049 * Age 65–80 years (vs. <65 years) 0.34 [0.16–0.74] 0.007 * Female sex 0.70 [0.32–1.52] 0.371 Hypertension 0.77 [0.38–1.55] 0.470 Dyslipidaemia 0.55 [0.24–1.26] 0.161 Diabetes mellitus 0.22 [0.05–1.01] 0.052 0.35 [0.06–1.93] 0.289 History of malignancy 0.42 [0.16–1.10] 0.079 Active smoking 2.05 [0.90–4.63] 0.086 Concomitant unruptured aneurysm 0.85 [0.37–1.93] 0.689 Use of antithrombotic 0.78 [0.14–4.15] 0.766 mRS 1 or 2 before SAH onset (vs. mRS 0) 0.32 [0.11–0.94] 0.038 * 0.52 [0.15–1.84] 0.311 SAH factor WFNS grade II (vs. grade I) 0.52 [0.25–1.09] 0.083 0.46 [0.20–1.03] 0.060 GCS 0.095 GCS 13 (vs. GCS 15) 0.36 [0.12–0.90] 0.031 * GCS 14 (vs. GCS 15) 0.62 [0.28–1.37] 0.234 Fisher group 3 (vs. 1,2) 1.16 [0.39–3.43] 0.791 Anterior circulation (vs. posterior) 0.16 [0.02–1.21] 0.076 0.16 [0.02–1.45] 0.104 With ICH (vs. without ICH) 0.83 [0.21–3.26] 0.784 Maximum diameter of aneurysm, mm 1.02 [0.91–1.15] 0.710 Operative factor Bypass surgery 0.38 [0.12–1.17] 0.092 Early surgery at day 0, 1 (vs. delayed surgery after day 2) 0.78 [0.20–1.88] 0.550 CI, confidence interval; GCS, Glasgow coma scale; ICH, intracerebral haemorrhage; OR, odds ratio; SAH, subarachnoid haemorrhage; WFNS, World Federation of Neurosurgical Societies * P values < 0.05 are considered significant. The associations between the postoperative adverse events and outcomes are shown in Table 4 . In the bivariate analysis, the postoperative events negatively correlated with favourable outcomes, including symptomatic infarction by surgery ( p = 0.002), postoperative rupture ( p = 0.047), postoperative additional surgery ( p = 0.003), epileptic seizure ( p < 0.001), meningitis ( p = 0.005), and secondary hydrocephalus ( p < 0.001). The systemic complications included pneumonia ( p = 0.009), gastrointestinal bleeding ( p = 0.019), and urinary tract infection ( p = 0.047). The development of DCI was not significantly correlated to favourable outcomes. Multivariable analysis identified symptomatic infarction caused by surgery (OR 0.04, 95% CI 0.01–0.27, p < 0.001), epileptic seizure (OR 0.11, 95% CI 0.03–0.36, p < 0.001), secondary hydrocephalus (OR 0.10, 95% CI 0.04–0.27, p < 0.001), and urinary tract infection (OR 0.06, 95% CI 0.01–0.74, p = 0.028) as significant negative factors. Table 4 Risk analysis of complication factors related to favourable outcomes after surgery for low-grade subarachnoid haemorrhage Bivariate Multivariable OR [95% CI] P -value OR [95% CI] P -value Postoperative surgical complications Symptomatic infarction by surgery 0.08 [0.02–0.38] 0.002 * 0.04 [0.01–0.27] < 0.001 * Oculomotor nerve palsy by surgery 1.59 [0.18–14.00] 0.677 Postoperative rupture 0.10 [0.01–0.97] 0.047 * Postoperative additional surgery 0.11 [0.03–0.47] 0.003 * 0.19 [0.03–1.10] 0.064 Total vasospasm 0.67 [0.33–1.34] 0.253 Delayed cerebral infarction 0.43 [0.14–1.29] 0.134 Epileptic seizure 0.14 [0.05–0.37] < 0.001 * 0.11 [0.03–0.36] < 0.001 * Meningitis 0.31 [0.14–0.70] 0.005 * Secondary hydrocephalus 0.13 [0.06–0.29] < 0.001 * 0.10 [0.04–0.27] < 0.001 * Systemic complications Pneumonia 0.23 [0.08–0.69] 0.009 * CSWS, DI, SIADH 0.54 [0.19–1.55] 0.251 Liver failure/ cholecystitis 0.47 [0.14–1.52] 0.208 Heart failure 0.37 [0.09–1.44] 0.151 Gastrointestinal bleeding 0.17 [0.04–0.74] 0.019 * Urinary tract infection 0.10 [0.01–0.97] 0.047 * 0.06 [0.01–0.74] 0.028 * Pulmonary embolisation 0.31 [0.02–5.04] 0.409 CI, confidence interval; ICH, intracerebral haemorrhage; OR, odds ratio; PA, pterional approach; WFNS, World Federation of Neurosurgical Societies * P values < 0.05 are considered significant. Prognostic risk classification by recursive partitioning analysis Starting with the age of 70 years as a significant partitioning factor, further optimal partitioning created the risk classification using RPA as shown in Fig. 1 . The favourable prognosis group included patients aged ≤ 70 years who did not require additional surgery or did not have secondary hydrocephalus and had a favourable outcome probability of 0.913. The intermediate prognosis group included patients aged ≤ 70 years who did not require additional surgery but had secondary hydrocephalus and patients aged > 70 years without epileptic seizures (favourable outcome probabilities of 0.599 and 0.572, respectively). The poor prognosis group included patients aged ≤ 70 years requiring additional surgery and those aged > 70 years with epileptic seizures (favourable outcome probabilities of 0.377 and 0.173, respectively). Nominal logistic regression for favourable outcomes across these groups showed significant differences, with ORs (95% CI) for favourable vs. intermediate, intermediate vs. poor, and favourable vs. poor of 7.95 (3.26–19.38, p < 0.001), 4.67 (1.31–16.59, p = 0.017), and 37.10 (10.25–134.31, p < 0.001), respectively (Table 5 ). Table 5 Prognostic model for predicts favourable outcomes after surgery for low-grade subarachnoid haemorrhage Prognosis group OR [95% CI] P -value Favourable (vs. intermediate) 7.95 [3.26–19.38] < 0.001 * Intermediate (vs. poor) 4.67 [1.31–16.59] 0.017 * Favourable (vs. poor) 37.10 [10.25–134.31] < 0.001 * CI, confidence interval; OR, odds ratio * P values < 0.05 are considered significant. Discussion This study demonstrated that age was a stronger prognostic factor than WFNS grading for patients with low-grade SAH (WFNS grade I/II) undergoing microsurgical clipping. Using 70 years as a cutoff, the study developed a clinically applicable risk evaluation method, dividing the patients into three groups (favourable, intermediate, and poor) based on age and postoperative adverse events. Initially, this study investigated the association between background factors related to patients, disease, and surgery with favourable outcomes (mRS 0–2 at discharge). The age at onset was the sole prognostic predictor, highlighting its importance in the prognosis of low-grade SAH. The WFNS grading system has been widely used since its introduction in 1988 to classify prognoses based on the level of consciousness at SAH onset [ 34 ], but some studies have reported no significant prognostic difference between WFNS grades [ 27 , 32 , 38 ]. Low-grade SAH (WFNS grades I and II) is generally considered to have a favourable prognosis, but distinguishing between grades can be challenging in older patients with pre-existing cognitive decline. Zijlmans et al. identified age as a background factor associated with unfavourable outcomes (mRS 3–6) at 6 months after treatment in 132 patients with WFNS grade I aneurysmal SAH [ 44 ]. Conversely, Hori et al. found no background factors, including age, associated with unfavourable outcomes (Glasgow Outcome Scale 1–3) at discharge in 171 patients with WFNS grade I and II SAH, making the findings controversial [ 13 ]. These studies included both surgical and endovascular treatments and had heterogeneous cohorts. In our study, age was a stronger prognostic factor for the surgical cohort, suggesting that the higher invasiveness of open surgery may be more impactful on the outcomes of older patients. Using the age of 70 years as a partitioning factor, the RPA in this study showed optimal partitioning based on surgical-related complications in patients younger than 70 years and epileptic seizures in those older than 70 years for the prediction of favourable outcomes. This indicates that surgical complications critically affected the mRS of younger patients, while postoperative seizures significantly impacted the outcomes in older patients. The association between poor outcomes and epilepsy at discharge has been reported, suggesting the need for careful surgical techniques to minimise complications [ 3 , 8 , 11 , 12 , 14 , 19 , 25 , 35 ]. Prophylactic antiepileptic drug administration to patients with SAH without seizures is debated [ 43 ], but it warrants consideration in older patients due to its potential impact on prognosis. Secondary hydrocephalus is a known predictor of poor outcomes for aneurysmal SAH, and this study confirmed its significance in patients under 70 years with low-grade SAH [ 1 , 29 , 41 ]. Previous studies have identified age as a risk factor for shunt-dependent hydrocephalus and its correlation with poor outcomes [ 1 , 29 ]. The association between hydrocephalus and prognosis in younger patients in this study is noteworthy, although the outcome measurement was mRS at discharge, which may not fully capture long-term recovery. This study has a few limitations. Firstly, it was a single-centre retrospective study, and selection bias may have occurred. Secondly, the outcome measurement was mRS at discharge, and long-term follow-up could not be conducted. Thirdly, the classification model has not been validated in a separate cohort. Multicentre prospective studies with long-term follow-up data are needed for further validation. Conclusion : Age was a more significant prognostic factor than WFNS grading in patients with WFNS grade I/II aneurysmal subarachnoid haemorrhage undergoing microsurgical clipping. The developed prognostic model with an age cut-off of 70 years and postoperative complications provides a practical tool for predicting outcomes and guiding treatment strategies. In that model, precise microsurgeries with fewer complications determined favourable outcomes beyond the WFNS grade for younger patients, while postoperative intensive seizure management could be meaningful to avoid poor outcomes for older patients. Declarations Funding: None Competing interests: The authors report no conflicts of interest concerning the materials or methods used in this study or the findings specified in this paper. Author contributions : All authors contributed to the study conception and design. Data collection and analysis were performed by Motoyuki Umekawa. The first draft of the manuscript was written by Motoyuki Umekawa and Gakushi Yoshikawa commented on previous versions of the manuscript. All authors read and approved the final manuscript. Ethics : This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Institutional Ethics Committee of Showa General Hospital (approval number REC-328). Consent to participate Informed consent was obtained from all individual participants included in the study. Consent to publish : Not applicable References Adams H, Ban VS, Leinonen V, Aoun SG, Huttunen J, Saavalainen T, Lindgren A, Frosen J, Fraunberg M, Koivisto T, Hernesniemi J, Welch BG, Jaaskelainen JE, Huttunen TJ (2016) Risk of Shunting After Aneurysmal Subarachnoid Hemorrhage: A Collaborative Study and Initiation of a Consortium. Stroke 47:2488–2496. 10.1161/STROKEAHA.116.013739 Anderson IA, Kailaya-Vasan A, Nelson RJ, Tolias CM (2018) Clipping aneurysms improves outcomes for patients undergoing coiling. J Neurosurg 1–7. 10.3171/2017.12.JNS172759 Baldvinsdottir B, Kronvall E, Ronne-Engstrom E, Enblad P, Lindvall P, Aineskog H, Friethriksson S, Klurfan P, Svensson M, Alpkvist P, Hillman J, Eneling J, Nilsson OG (2023) Adverse events associated with microsurgial treatment for ruptured intracerebral aneurysms: a prospective nationwide study on subarachnoid haemorrhage in Sweden. J Neurol Neurosurg Psychiatry 94:575–580. 10.1136/jnnp-2022-330982 Brawanski N, Kunze F, Bruder M, Tritt S, Senft C, Berkefeld J, Seifert V, Konczalla J (2017) Subarachnoid Hemorrhage in Advanced Age: Comparison of Patients Aged 70–79 Years and 80 Years and Older. World Neurosurg 106:139–144. 10.1016/j.wneu.2017.06.056 Campi A, Ramzi N, Molyneux AJ, Summers PE, Kerr RS, Sneade M, Yarnold JA, Rischmiller J, Byrne JV (2007) Retreatment of ruptured cerebral aneurysms in patients randomized by coiling or clipping in the International Subarachnoid Aneurysm Trial (ISAT). Stroke 38:1538–1544. 10.1161/STROKEAHA.106.466987 Chiang VL, Claus EB, Awad IA (2000) Toward more rational prediction of outcome in patients with high-grade subarachnoid hemorrhage. Neurosurgery 46:28–35 discussion 35 – 26 Daou BJ, Koduri S, Thompson BG, Chaudhary N, Pandey AS (2019) Clinical and experimental aspects of aneurysmal subarachnoid hemorrhage. CNS Neurosci Ther 25:1096–1112. 10.1111/cns.13222 Darkwah Oppong M, Lohrer L, Wrede KH, Chihi M, Santos AN, Dammann P, Michel A, Rauschenbach L, Said M, Li Y, Frank B, Sure U, Jabbarli R (2023) Reevaluation of risk factors for aneurysmal subarachnoid hemorrhage associated epilepsy. J Neurol Sci 444:120519. 10.1016/j.jns.2022.120519 Davies JM, Lawton MT (2014) Advances in open microsurgery for cerebral aneurysms. Neurosurg 74 Suppl 1S7–16. 10.1227/NEU.0000000000000193 Frontera JA, Fernandez A, Schmidt JM, Claassen J, Wartenberg KE, Badjatia N, Connolly ES, Mayer SA (2009) Defining vasospasm after subarachnoid hemorrhage: what is the most clinically relevant definition? Stroke 40:1963–1968. 10.1161/STROKEAHA.108.544700 Hart Y, Sneade M, Birks J, Rischmiller J, Kerr R, Molyneux A (2011) Epilepsy after subarachnoid hemorrhage: the frequency of seizures after clip occlusion or coil embolization of a ruptured cerebral aneurysm: results from the International Subarachnoid Aneurysm Trial. J Neurosurg 115:1159–1168. 10.3171/2011.6.JNS101836 Hirano T, Enatsu R, Iihoshi S, Mikami T, Honma T, Ohnishi H, Mikuni N (2019) Effects of Hemosiderosis on Epilepsy Following Subarachnoid Hemorrhage. Neurol Med Chir (Tokyo) 59:27–32. 10.2176/nmc.oa.2018-0125 Hori S, Masuoka T, Hamada H, Okamoto S, Kubo M, Horie Y, Kuroda S (2023) Walk-In Hospital Admission of Patients with Subarachnoid Hemorrhage: Clinical Presentation and Outcome. World Neurosurg 179:e421–e427. 10.1016/j.wneu.2023.08.112 Huttunen J, Kurki MI, Fraunberg MVZ, Koivisto T, Ronkainen A, Rinne J, Jääskeläinen JE, Kälviäinen R, Immonen A (2015) Epilepsy after aneurysmal subarachnoid hemorrhage A population-based, long-term follow-up study. Neurology 84:2229–2237. 10.1212/Wnl.0000000000001643 Inagawa T, Kamiya K, Ogasawara H, Yano T (1987) Rebleeding of ruptured intracranial aneurysms in the acute stage. Surg Neurol 28:93–99. 10.1016/0090-3019(87)90079-6 Kurogi R, Kada A, Ogasawara K, Kitazono T, Sakai N, Hashimoto Y, Shiokawa Y, Miyachi S, Matsumaru Y, Iwama T, Tominaga T, Onozuka D, Nishimura A, Arimura K, Kurogi A, Ren N, Hagihara A, Nakaoku Y, Arai H, Miyamoto S, Nishimura K, Iihara K (2020) Effects of case volume and comprehensive stroke center capabilities on patient outcomes of clipping and coiling for subarachnoid hemorrhage. J Neurosurg 134:929–939. 10.3171/2019.12.JNS192584 Kurogi R, Kada A, Ogasawara K, Nishimura K, Kitazono T, Iwama T, Matsumaru Y, Sakai N, Shiokawa Y, Miyachi S, Kuroda S, Shimizu H, Yoshimura S, Osato T, Horie N, Nagata I, Nozaki K, Date I, Hashimoto Y, Hoshino H, Nakase H, Kataoka H, Ohta T, Fukuda H, Tamiya N, Kurogi AI, Ren N, Nishimura A, Arimura K, Shimogawa T, Yoshimoto K, Onozuka D, Ogata S, Hagihara A, Saito N, Arai H, Miyamoto S, Tominaga T, Iihara K, Collaborators JAS (2023) National trends in the outcomes of subarachnoid haemorrhage and the prognostic influence of stroke centre capability in Japan: retrospective cohort study. BMJ Open 13:e068642. 10.1136/bmjopen-2022-068642 Lantigua H, Ortega-Gutierrez S, Schmidt JM, Lee K, Badjatia N, Agarwal S, Claassen J, Connolly ES, Mayer SA (2015) Subarachnoid hemorrhage: who dies, and why? Crit Care 19. 10.1186/s13054-015-1036-0 Le VT, Nguyen AM, Nguyen PL (2024) Risk Factors for In-Hospital Seizure and New-Onset Epilepsy in Coiling and Clipping Treatment of Aneurysmal Subarachnoid Hemorrhage. World Neurosurg 184:e460–e467. 10.1016/j.wneu.2024.01.146 Macdonald RL, Pluta RM, Zhang JH (2007) Cerebral vasospasm after subarachnoid hemorrhage: the emerging revolution. Nat Clin Pract Neurol 3:256–263. 10.1038/ncpneuro0490 Mayberg MR, Batjer HH, Dacey R, Diringer M, Haley EC, Heros RC, Sternau LL, Torner J, Adams HP Jr., Feinberg W et al (1994) Guidelines for the management of aneurysmal subarachnoid hemorrhage. A statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke 25:2315–2328. 10.1161/01.str.25.11.2315 Mijiti M, Mijiti P, Axier A, Amuti M, Guohua Z, Xiaojiang C, Kadeer K, Xixian W, Geng D, Maimaitili A (2016) Incidence and Predictors of Angiographic Vasospasm, Symptomatic Vasospasm and Cerebral Infarction in Chinese Patients with Aneurysmal Subarachnoid Hemorrhage. PLoS ONE 11:e0168657. 10.1371/journal.pone.0168657 Mocco J, Ransom ER, Komotar RJ, Schmidt JM, Sciacca RR, Mayer SA, Connolly ES Jr (2006) Preoperative prediction of long-term outcome in poor-grade aneurysmal subarachnoid hemorrhage. Neurosurgery 59:529–538; discussion 529–538. 10.1227/01.NEU.0000228680.22550.A2 Molyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, Holman R, International Subarachnoid Aneurysm Trial Collaborative G (2002) International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 360:1267–1274. 10.1016/s0140-6736(02)11314-6 Nakashima S, Nishibayashi H, Yako R, Ishii M, Toki N, Tomobuchi M, Nakai T, Yamoto H, Nakanishi Y, Nakao N (2024) Factors Associated with Early and Late Seizure Related to Aneurysmal Subarachnoid Hemorrhage. Neurol Med Chir (Tokyo) 64:123–130. 10.2176/jns-nmc.2023-0201 Natarajan SK, Sekhar LN, Ghodke B, Britz GW, Bhagawati D, Temkin N (2008) Outcomes of ruptured intracranial aneurysms treated by microsurgical clipping and endovascular coiling in a high-volume center. AJNR Am J Neuroradiol 29:753–759. 10.3174/ajnr.A0895 Nguyen TA, Vu LD, Mai TD, Dao CX, Ngo HM, Hoang HB, Do SN, Nguyen HT, Pham DT, Nguyen MH, Nguyen DN, Vuong HTT, Vu HD, Nguyen DD, Nguyen LQ, Dao PV, Vu TD, Nguyen DT, Tran TA, Pham TQ, Van Nguyen C, Nguyen AD, Luong CQ (2023) Predictive validity of the prognosis on admission aneurysmal subarachnoid haemorrhage scale for the outcome of patients with aneurysmal subarachnoid haemorrhage. Sci Rep 13:6721. 10.1038/s41598-023-33798-5 Oka F, Sadeghian H, Yaseen MA, Fu B, Kura S, Qin T, Sakadzic S, Sugimoto K, Inoue T, Ishihara H, Nomura S, Suzuki M, Ayata C (2022) Intracranial pressure spikes trigger spreading depolarizations. Brain 145:194–207. 10.1093/brain/awab256 Paisan GM, Ding D, Starke RM, Crowley RW, Liu KC (2018) Shunt-Dependent Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage: Predictors and Long-Term Functional Outcomes. Neurosurgery 83:393–402. 10.1093/neuros/nyx393 Pluta RM, Hansen-Schwartz J, Dreier J, Vajkoczy P, Macdonald RL, Nishizawa S, Kasuya H, Wellman G, Keller E, Zauner A, Dorsch N, Clark J, Ono S, Kiris T, Leroux P, Zhang JH (2009) Cerebral vasospasm following subarachnoid hemorrhage: time for a new world of thought. Neurol Res 31:151–158. 10.1179/174313209X393564 Rosen DS, Macdonald RL (2005) Subarachnoid hemorrhage grading scales: a systematic review. Neurocrit Care 2:110–118. 10.1385/NCC:2:2 Sano H, Satoh A, Murayama Y, Kato Y, Origasa H, Inamasu J, Nouri M, Cherian I, Saito N, members of the 38 registered i, Disease WC, Treatment C (2015) Modified World Federation of Neurosurgical Societies subarachnoid hemorrhage grading system. World Neurosurg 83:801–807. 10.1016/j.wneu.2014.12.032 Tanno Y, Homma M, Oinuma M, Kodama N, Ymamoto T (2007) Rebleeding from ruptured intracranial aneurysms in North Eastern Province of Japan. A cooperative study. J Neurol Sci 258:11–16. 10.1016/j.jns.2007.01.074 Teasdale GM, Drake CG, Hunt W, Kassell N, Sano K, Pertuiset B, De Villiers JC (1988) A universal subarachnoid hemorrhage scale: report of a committee of the World Federation of Neurosurgical Societies. J Neurol Neurosurg Psychiatry 51:1457. 10.1136/jnnp.51.11.1457 Todd MM (2020) Erratum. Acute postoperative neurological deterioration associated with surgery for ruptured intracranial aneurysm: incidence, predictors, and outcomes. J Neurosurg 132:2009. 10.3171/2020.1.JNS111277a Umekawa M, Yoshikawa G (2023) Impact of ventriculo-cisternal irrigation on prevention of delayed cerebral infarction in aneurysmal subarachnoid hemorrhage: a single-center retrospective study and literature review. Neurosurg Rev 47:6. 10.1007/s10143-023-02241-8 van der Schaaf I, Algra A, Wermer M, Molyneux A, Clarke M, van Gijn J, Rinkel G (2005) Endovascular coiling versus neurosurgical clipping for patients with aneurysmal subarachnoid haemorrhage. Cochrane Database Syst Rev:CD003085. 10.1002/14651858.CD003085.pub2 van Donkelaar CE, Bakker NA, Veeger NJ, Uyttenboogaart M, Metzemaekers JD, Eshghi O, Mazuri A, Foumani M, Luijckx GJ, Groen RJ, van Dijk JM (2017) Prediction of outcome after subarachnoid hemorrhage: timing of clinical assessment. J Neurosurg 126:52–59. 10.3171/2016.1.JNS152136 Vergouwen MDI, Vermeulen M, van Gijn J, Rinkel GJE, Wijdicks EF, Muizelaar JP, Mendelow AD, Juvela S, Yonas H, Terbrugge KG, Macdonald RL, Diringer MN, Broderick JP, Dreier JP, Roos YBWEM (2010) Definition of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage as an Outcome Event in Clinical Trials and Observational Studies Proposal of a Multidisciplinary Research Group. Stroke 41:2391–2395. 10.1161/Strokeaha.110.589275 Waldron JS, Halbach VV, Lawton MT (2009) Microsurgical management of incompletely coiled and recurrent aneurysms: trends, techniques, and observations on coil extrusion. Neurosurgery 64:301–315 discussion 315 – 307. 10.1227/01.NEU.0000335178.15274.B4 Xie Z, Hu X, Zan X, Lin S, Li H, You C (2017) Predictors of Shunt-dependent Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage? A Systematic Review and Meta-Analysis. World Neurosurg 106:844–860e846. 10.1016/j.wneu.2017.06.119 Yue Q, Liu Y, Leng B, Xu B, Gu Y, Chen L, Zhu W, Mao Y (2016) A Prognostic Model for Early Post-Treatment Outcome of Elderly Patients With Aneurysmal Subarachnoid Hemorrhage. World Neurosurg 95:253–261. 10.1016/j.wneu.2016.08.020 Zafar SF, Rosenthal ES, Postma EN, Sanches P, Ayub MA, Rajan S, Kim JA, Rubin DB, Lee H, Patel AB, Hsu J, Patorno E, Westover MB (2022) Antiseizure Medication Treatment and Outcomes in Patients with Subarachnoid Hemorrhage Undergoing Continuous EEG Monitoring. Neurocrit Care 36:857–867. 10.1007/s12028-021-01387-x Zijlmans JL, Coert BA, van den Berg R, Sprengers MES, Majoie C, Vandertop WP, Verbaan D (2018) Unfavorable Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage WFNS Grade I. World Neurosurg 118:e217–e222. 10.1016/j.wneu.2018.06.157 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 Oct, 2024 Read the published version in Neurosurgical Review → Version 1 posted Editorial decision: Revision requested 03 Oct, 2024 Reviews received at journal 02 Oct, 2024 Reviewers agreed at journal 22 Sep, 2024 Reviewers agreed at journal 19 Sep, 2024 Reviews received at journal 18 Sep, 2024 Reviewers agreed at journal 18 Sep, 2024 Reviewers agreed at journal 29 Aug, 2024 Reviewers invited by journal 28 Aug, 2024 Editor assigned by journal 28 Aug, 2024 Submission checks completed at journal 19 Aug, 2024 First submitted to journal 15 Aug, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4922161","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":350354703,"identity":"25a018ab-bac7-4207-8415-90ca427e804b","order_by":0,"name":"Motoyuki Umekawa","email":"data:image/png;base64,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","orcid":"","institution":"Showa General Hospital","correspondingAuthor":true,"prefix":"","firstName":"Motoyuki","middleName":"","lastName":"Umekawa","suffix":""},{"id":350354704,"identity":"94e76dbc-409a-4927-bcb9-93826842fd3d","order_by":1,"name":"Gakushi Yoshikawa","email":"","orcid":"","institution":"Showa General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gakushi","middleName":"","lastName":"Yoshikawa","suffix":""}],"badges":[],"createdAt":"2024-08-16 03:26:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4922161/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4922161/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10143-024-03067-8","type":"published","date":"2024-10-30T16:13:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":66632169,"identity":"ada938db-4871-4647-b019-d203d236179e","added_by":"auto","created_at":"2024-10-15 04:56:54","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":555495,"visible":true,"origin":"","legend":"\u003cp\u003eRecursive partitioning analysis of favourable outcomes (mRS 0–2 at discharge) in a predictive model with three outcomes based on age dichotomisation using the Youden index for 70 years\u003c/p\u003e","description":"","filename":"Figure1RPALGSAH.png","url":"https://assets-eu.researchsquare.com/files/rs-4922161/v1/c1edddbaddcee4dce19d0fdf.png"},{"id":68206857,"identity":"663112c0-63f1-45cb-96f9-43be14b10e03","added_by":"auto","created_at":"2024-11-04 16:33:35","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1162247,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4922161/v1/d8533632-1d29-401f-adf6-229948fa377b.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Impact of age on surgical outcomes for World Federation of Neurosurgical Societies grade I and II aneurysmal subarachnoid haemorrhage: a novel prognostic model using recursive partitioning analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eSubarachnoid haemorrhage (SAH) has an incidence of 1\u0026ndash;20 cases per 100,000 population, with approximately 85% of cases caused by ruptured aneurysms\u0026nbsp;[21,28]. Rerupture of aneurysms leading to SAH has a mortality rate of 50\u0026ndash;60%. Therefore, surgical intervention to prevent rerupture\u0026nbsp;is\u0026nbsp;the primary step for SAH treatment\u0026nbsp;[15,18,33]. Treatment approaches can be broadly divided into microsurgery, such as clipping or trapping with bypass, and endovascular treatments, primarily coiling\u0026nbsp;[16,24,26]. The frequency of clipping for SAH has decreased with advances in endovascular devices\u0026nbsp;[17,37], but the rate of recurrence of aneurysms after clipping is lower than that after coiling\u0026nbsp;[2,5,9,40]. Therefore, our institution actively performs microsurgical clipping for aneurysmal SAH from a curative standpoint. However, less invasive endovascular treatments may be selected for older adults or those with poor surgical tolerance, depending on their general condition.\u003c/p\u003e\n\u003cp\u003eThe World Federation of Neurosurgical Societies (WFNS) classification evaluates severity based on the level of consciousness and the presence of neurological symptoms and is widely used as the gold standard due to its correlation with prognosis\u0026nbsp;[34]. While low-grade SAH (WFNS grade I and II) generally has a better prognosis than\u0026nbsp;higher-grade SAH (WFNS grade\u0026nbsp;III-V), outcomes are not always favourable due to factors such as patient background, surgical complications, and adverse events arising from the management of vasospasm or systemic complications\u0026nbsp;[3,7,10,20,22,30,35,44]. Although various factors influencing prognosis in low-grade SAH have been examined, the evidence remains insufficient. The age at onset has been reported as a prognostic factor for SAH and is simple to evaluate\u0026nbsp;[4,6,23,31,42]. However, few studies have investigated the effects of age on low-grade SAH outcomes.\u003c/p\u003e\n\u003cp\u003eHence, in this study, we aimed to explore the prognostic factors of patients who underwent microsurgical clipping for WFNS grade I and II SAH and develop a simple prognostic model mainly based on patient age of onset.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003e\u003cu\u003eParticipant selection\u003c/u\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe collected data on patients who developed SAH from ruptured cerebral aneurysms (including dissecting aneurysms) between December 2010 and January 2020 and underwent open surgery, using an institutional SAH database. Patients whose modified Rankin scores (mRS) were \u0026ge;3 were excluded. Data regarding patient-, aneurysm-, SAH-, and surgery-related factors and clinical outcomes that were prospectively collected and recorded in the database were retrospectively evaluated. Informed consent was obtained from all participants, and the study was approved by the Institutional Ethics Committee of Showa General Hospital (approval number REC-328).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cu\u003eProcedures and techniques of SAH management\u003c/u\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe treatment protocol for low-grade SAH via microsurgical clipping at our institution was as follows: Initially, digital subtraction angiography (DSA) was performed under sedation and analgesia to determine the treatment strategy. If patients visited within three days of SAH onset, surgery was performed on the same day or the following day. For patients arriving after the fourth day of onset, the timing of surgery depends on the initial DSA findings of vasospasm and the patient\u0026apos;s general condition. Ventricular and cisternal or lumbar drainage is employed postoperatively for ventriculo-cisternal irrigation and intracranial pressure control therapy. Postoperative management of SAH has been described in detail in previous studies [36]. Imaging evaluation primarily involved CT scans to assess SAH distribution until day 3. On day 4, an MRI is performed to evaluate early ischaemic lesions and vascular conditions before the vasospasm. On day 7, DSA was performed to detect cerebral vasospasm and aneurysms. MRI is repeated on day 14 to detect late-stage vasospasms and ischaemic lesions. Additionally, shunt surgery was performed if symptomatic post-SAH hydrocephalus occurred, and appropriate general medical treatment was performed if needed throughout the time course.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cu\u003eTreatment outcomes and statistical analyses\u003c/u\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe median and interquartile ranges (IQR) were calculated for each factor. The primary outcome was the mRS at discharge, with a favourable outcome defined as mRS 0\u0026ndash;2. The following complications were assessed in the safety evaluation: emergent additional surgery, vasospasm, delayed cerebral infarction (DCI), epileptic seizures, secondary hydrocephalus (shunt placement excluded from additional surgery), meningitis, and systemic medical complications. Vasospasm was defined as any angiographical vasospasm detected by DSA or magnetic resonance angiography (MRA) with a decrease of \u0026ge;50% in the cerebral artery diameter relative to the preoperative value. This was judged solely on radiological findings, regardless of symptoms\u0026nbsp;[10]. DCI was defined as symptomatic infarction identified on CT or MRI after excluding surgery-related infarction with any angiographical vasospasm\u0026nbsp;[39].\u003c/p\u003e\n\u003cp\u003eTo create a prognostic model for favourable outcomes, bivariate and multivariable logistic regression analyses were performed for the patient background factors, including age and WFNS grade, SAH factors, and surgical factors. Factors showing significance in the bivariate analysis were included in the multivariable analysis along with age and WFNS grade. Further analysis using factors related to postoperative adverse events was conducted to assess their association with favourable outcomes. In this analysis, factors for multivariable analysis were selected using a stepwise forward selection method with a P-value threshold of \u0026lt;0.10. A cutoff value for age as a continuous variable was calculated from the receiver operating characteristic (ROC) curve using the Youden index, creating a two-group division for age. Finally, recursive partitioning analysis (RPA) used patient background, including dichotomised age and other significant factors from the bivariate analysis, to develop a three-group prognostic model (favourable, intermediate, poor) for favourable outcomes. P-values of \u0026lt;.05 denoted statistical significance. Statistical analyses were performed using JMP Pro 17 software (SAS Institute Inc., Cary, NC, USA).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cu\u003eData Availability\u003c/u\u003e\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe authors confirm that data collected for the study and analysis methods will be shared upon reasonable request from any qualified investigator.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eParticipant selection\u003c/h2\u003e \u003cp\u003eWe obtained data on 373 patients who developed SAH due to ruptured cerebral aneurysms (including dissecting aneurysms) between December 2010 and January 2020 and underwent open surgery from an institutional SAH database. Of them, 188 with WFNS grades I and II SAH were identified. After excluding 12 patients whose modified Rankin scores (mRS) were 3 or more, 176 (75 patients with WFNS grade I and 101 with grade II) were included in this study.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipant baseline characteristics and surgery for SAH\u003c/h2\u003e \u003cp\u003eThe median age of the 176 patients with low-grade aneurysmal SAH included in this study was 57 years (IQR, 47\u0026ndash;70 years), and females were predominant (68%, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Hypertension was the most common comorbidity (52%), while diabetes mellitus was rare (4%). Fifteen patients (9%) already had mRS scores of 1 or 2 before SAH onset. For 93% of the patients, the aneurysm type was saccular, with the distribution of the aneurysm locations consistent with that of the general population. The pterional approach was the most frequent surgical approach, and bypass was used in 7% of surgeries involving clipping or trapping. Most surgeries were performed on the day of onset or the following day.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline characteristics of patients with aneurysmal subarachnoid haemorrhage and surgical procedures\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber (%)/Median [IQR]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePatient factor\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge, years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57 [47\u0026ndash;70]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale sex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e120 (68%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eComorbidities\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHypertension\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e92 (52%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDyslipidaemia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33 (19%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes mellitus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of malignancy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20 (11%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eActive smoking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57 (32%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcomitant unruptured aneurysm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38 (22%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUse of antithrombotic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emRS 1 or 2 before SAH onset\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSAH factor\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWFNS grading\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75 (43%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e101 (57%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGCS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75 (43%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75 (43%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26 (15%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAneurysm type\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSaccular\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e163 (93%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaximum dome diameter, mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.0 [3.9\u0026ndash;7.0]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDissecting\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaximum length, mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.3 [3.2\u0026ndash;9.9]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLocation of aneurysm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAcom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46 (26%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIC-Pcom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44 (25%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMCA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e38 (22%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIC-Ach\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12 (7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIC C2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDistal ACA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther posterior circulation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFisher group 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e157 (89%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcomitant ICH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSurgical factor\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eApproach\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePterional\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e143 (81%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eInterhemispheric\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (13%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSuboccipital\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11 (6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBypass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHigh-flow bypass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (50%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow-flow bypass\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7 (50%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDay of surgery from onset\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDay 0,1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e141 (80%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDay 2\u0026ndash;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22 (13%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDay 5 or later\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eACA, anterior cerebral artery; Acom, anterior communicating artery; BA, basilar artery; GCS, Glasgow coma scale; ICH, intracerebral haemorrhage; IC-Pcom, internal carotid artery-posterior communicating artery; IQR, interquartile range; MCA, middle cerebral artery; VA, vertebral artery; WFNS, World Federation of Neurosurgical Societies\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eVariables are indicated as number (%) and median [interquartile range].\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ePrimary outcome and postoperative adverse events\u003c/h2\u003e \u003cp\u003eAt discharge, the mRS score was 0 for 65 (37%), 1 for 30 (17%), 2 for 39 (22%), 3 for 19 (11%), 4 for 19 (11%), 5 for 2 (1%), and 6 for 2 (1%) patients. The overall rate of favourable outcomes was 76%, with 22% of the patients having mRS of 3 or 4 and 2% having mRS of 5 or 6. Among the patients who died, one was an 83-year-old man who experienced postoperative rerupture of a 15-mm internal carotid artery-anterior choroidal artery aneurysm, and his family opted to withdraw from further treatment due to his advanced age. The other patient was a 60-year-old woman undergoing active treatment for breast cancer who experienced severe SAH from a newly ruptured vertebral artery dissecting aneurysm after clipping for an anterior communicating artery aneurysm.\u003c/p\u003e \u003cp\u003eAll the postoperative adverse events are summarised in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Symptomatic cerebral infarction due to surgery occurred in 5% of the patients. Emergent additional surgery for postoperative haemorrhage, cerebral swelling, or aneurysm rerupture was performed for 10 patients (6%). Only 9% of the patients developed DCI, despite 49% having confirmed vasospasm. Epileptic seizures occurred in 21 patients (12%), all of which required antiepileptic drug treatment. Meningitis (requiring extended antibiotic therapy) affected 32 patients (18%). Symptomatic secondary hydrocephalus requiring shunt placement occurred in 43 patients (19%). Pneumonia and electrolyte abnormalities due to cerebral salt-wasting syndrome, diabetes insipidus, and the syndrome of inappropriate antidiuretic hormone secretion were the most common systemic complications. Each occurred in 15 patients (9%) with no associated deaths.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDetails of postoperative and systemic complications after surgery for low-grade SAH\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNumber (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePostoperative complication\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptomatic infarction by surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOculomotor nerve palsy by surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6 (3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperative rupture\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperative additional surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10 (6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal vasospasm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87 (49%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDelayed cerebral infarction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEpileptic seizure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21 (12%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMeningitis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32 (18%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSecondary hydrocephalus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43 (19%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSystemic complication\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePneumonia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCSWS, DI, SIADH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15 (9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLiver failure/ cholecystitis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13 (7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeart failure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9 (5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGastrointestinal bleeding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8 (5%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrinary tract infection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4 (2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePulmonary embolisation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2 (1%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eCSWS, cerebral salt-wasting syndrome; DI, diabetes insipidus; SIADH, syndrome of inappropriate antidiuretic hormone secretion\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eValues are indicated as number (%).\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eAnalyses of favourable outcomes using background factors and adverse events\u003c/h2\u003e \u003cp\u003eIn the bivariate analysis, significant negative correlations with favourable outcomes were found for age (continuous, per increasing decade, odds ratio [OR] 0.51, 95% confidence interval [CI] 0.38\u0026ndash;0.69, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and mRS 1 or 2 before SAH onset (OR 0.32, 95% CI 0.11\u0026ndash;0.94, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.038). WFNS grade II against grade I did not show statistical significance (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.083, Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). In the multivariable analysis, age (per increasing decade, OR 0.55, 95% CI 0.40\u0026ndash;0.76, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) was the only significant negative factor for favourable outcomes, making it a key result of this study. ROC curve analysis for age and favourable outcomes showed an area under the curve of 0.737, with the age of 70 years having a sensitivity of 0.866, specificity of 0.500, positive predictive value of 0.847, and negative predictive value of 0.538. Patients aged\u0026thinsp;\u0026le;\u0026thinsp;70 years had significantly better outcomes than those aged\u0026thinsp;\u0026gt;\u0026thinsp;70 years (favourable outcome: 84% vs. 46%, respectively; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAnalysis of baseline factors related to favourable outcomes after surgery for low-grade subarachnoid haemorrhage\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBivariate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMultivariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR [95% CI]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOR [95% CI]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePatient factor\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (continuous, per increasing decade)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.51 [0.38\u0026ndash;0.69]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.55 [0.40\u0026ndash;0.76]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDichotomised\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026thinsp;\u0026gt;\u0026thinsp;70 years (vs. \u0026le;70 years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.16 [0.07\u0026ndash;0.34]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStratified\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026thinsp;\u0026gt;\u0026thinsp;80 years (vs. \u0026lt;65 years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.08 [0.02\u0026ndash;0.33]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u0026thinsp;\u0026gt;\u0026thinsp;80 years (vs. 65\u0026ndash;80 years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.23 [0.05\u0026ndash;1.00]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.049\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge 65\u0026ndash;80 years (vs. \u0026lt;65 years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.34 [0.16\u0026ndash;0.74]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.007\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale sex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.70 [0.32\u0026ndash;1.52]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.371\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHypertension\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.77 [0.38\u0026ndash;1.55]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.470\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDyslipidaemia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.55 [0.24\u0026ndash;1.26]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.161\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes mellitus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.22 [0.05\u0026ndash;1.01]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.052\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.35 [0.06\u0026ndash;1.93]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.289\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of malignancy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.42 [0.16\u0026ndash;1.10]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.079\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eActive smoking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.05 [0.90\u0026ndash;4.63]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.086\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eConcomitant unruptured aneurysm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.85 [0.37\u0026ndash;1.93]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.689\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUse of antithrombotic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.78 [0.14\u0026ndash;4.15]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emRS 1 or 2 before SAH onset (vs. mRS 0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.32 [0.11\u0026ndash;0.94]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.038\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.52 [0.15\u0026ndash;1.84]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.311\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSAH factor\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWFNS grade II (vs. grade I)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.52 [0.25\u0026ndash;1.09]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.083\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.46 [0.20\u0026ndash;1.03]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.060\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGCS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.095\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGCS 13 (vs. GCS 15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.36 [0.12\u0026ndash;0.90]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.031\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGCS 14 (vs. GCS 15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.62 [0.28\u0026ndash;1.37]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.234\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFisher group 3 (vs. 1,2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.16 [0.39\u0026ndash;3.43]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.791\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior circulation (vs. posterior)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.16 [0.02\u0026ndash;1.21]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.076\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.16 [0.02\u0026ndash;1.45]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.104\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWith ICH (vs. without ICH)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.83 [0.21\u0026ndash;3.26]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.784\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaximum diameter of aneurysm, mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.02 [0.91\u0026ndash;1.15]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.710\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eOperative factor\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBypass surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.38 [0.12\u0026ndash;1.17]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.092\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEarly surgery at day 0, 1 (vs. delayed surgery after day 2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.78 [0.20\u0026ndash;1.88]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.550\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eCI, confidence interval; GCS, Glasgow coma scale; ICH, intracerebral haemorrhage; OR, odds ratio; SAH, subarachnoid haemorrhage; WFNS, World Federation of Neurosurgical Societies\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*\u003cem\u003eP\u003c/em\u003e values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 are considered significant.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe associations between the postoperative adverse events and outcomes are shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. In the bivariate analysis, the postoperative events negatively correlated with favourable outcomes, including symptomatic infarction by surgery (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002), postoperative rupture (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.047), postoperative additional surgery (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003), epileptic seizure (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), meningitis (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005), and secondary hydrocephalus (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The systemic complications included pneumonia (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.009), gastrointestinal bleeding (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.019), and urinary tract infection (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.047). The development of DCI was not significantly correlated to favourable outcomes. Multivariable analysis identified symptomatic infarction caused by surgery (OR 0.04, 95% CI 0.01\u0026ndash;0.27, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), epileptic seizure (OR 0.11, 95% CI 0.03\u0026ndash;0.36, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), secondary hydrocephalus (OR 0.10, 95% CI 0.04\u0026ndash;0.27, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and urinary tract infection (OR 0.06, 95% CI 0.01\u0026ndash;0.74, p\u0026thinsp;=\u0026thinsp;0.028) as significant negative factors.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRisk analysis of complication factors related to favourable outcomes after surgery for low-grade subarachnoid haemorrhage\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBivariate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMultivariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR [95% CI]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOR [95% CI]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003ePostoperative surgical complications\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptomatic infarction by surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.08 [0.02\u0026ndash;0.38]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.002\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.04 [0.01\u0026ndash;0.27]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOculomotor nerve palsy by surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.59 [0.18\u0026ndash;14.00]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.677\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperative rupture\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.10 [0.01\u0026ndash;0.97]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.047\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostoperative additional surgery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.11 [0.03\u0026ndash;0.47]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.003\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.19 [0.03\u0026ndash;1.10]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.064\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal vasospasm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.67 [0.33\u0026ndash;1.34]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.253\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDelayed cerebral infarction\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.43 [0.14\u0026ndash;1.29]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.134\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEpileptic seizure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.14 [0.05\u0026ndash;0.37]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.11 [0.03\u0026ndash;0.36]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMeningitis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.31 [0.14\u0026ndash;0.70]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.005\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSecondary hydrocephalus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.13 [0.06\u0026ndash;0.29]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.10 [0.04\u0026ndash;0.27]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSystemic complications\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePneumonia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.23 [0.08\u0026ndash;0.69]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.009\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCSWS, DI, SIADH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.54 [0.19\u0026ndash;1.55]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLiver failure/ cholecystitis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.47 [0.14\u0026ndash;1.52]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.208\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeart failure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.37 [0.09\u0026ndash;1.44]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.151\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGastrointestinal bleeding\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.17 [0.04\u0026ndash;0.74]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.019\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUrinary tract infection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.10 [0.01\u0026ndash;0.97]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.047\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.06 [0.01\u0026ndash;0.74]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.028\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePulmonary embolisation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.31 [0.02\u0026ndash;5.04]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.409\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eCI, confidence interval; ICH, intracerebral haemorrhage; OR, odds ratio; PA, pterional approach; WFNS, World Federation of Neurosurgical Societies\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e*\u003cem\u003eP\u003c/em\u003e values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 are considered significant.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003ePrognostic risk classification by recursive partitioning analysis\u003c/h2\u003e \u003cp\u003eStarting with the age of 70 years as a significant partitioning factor, further optimal partitioning created the risk classification using RPA as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The favourable prognosis group included patients aged\u0026thinsp;\u0026le;\u0026thinsp;70 years who did not require additional surgery or did not have secondary hydrocephalus and had a favourable outcome probability of 0.913. The intermediate prognosis group included patients aged\u0026thinsp;\u0026le;\u0026thinsp;70 years who did not require additional surgery but had secondary hydrocephalus and patients aged\u0026thinsp;\u0026gt;\u0026thinsp;70 years without epileptic seizures (favourable outcome probabilities of 0.599 and 0.572, respectively). The poor prognosis group included patients aged\u0026thinsp;\u0026le;\u0026thinsp;70 years requiring additional surgery and those aged\u0026thinsp;\u0026gt;\u0026thinsp;70 years with epileptic seizures (favourable outcome probabilities of 0.377 and 0.173, respectively). Nominal logistic regression for favourable outcomes across these groups showed significant differences, with ORs (95% CI) for favourable vs. intermediate, intermediate vs. poor, and favourable vs. poor of 7.95 (3.26\u0026ndash;19.38, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), 4.67 (1.31\u0026ndash;16.59, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.017), and 37.10 (10.25\u0026ndash;134.31, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), respectively (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePrognostic model for predicts favourable outcomes after surgery for low-grade subarachnoid haemorrhage\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrognosis group\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR [95% CI]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFavourable (vs. intermediate)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7.95 [3.26\u0026ndash;19.38]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntermediate (vs. poor)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.67 [1.31\u0026ndash;16.59]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.017\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFavourable (vs. poor)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e37.10 [10.25\u0026ndash;134.31]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eCI, confidence interval; OR, odds ratio\u003c/td\u003e\u003c/tr\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003e*\u003cem\u003eP\u003c/em\u003e values\u0026thinsp;\u0026lt;\u0026thinsp;0.05 are considered significant.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study demonstrated that age was a stronger prognostic factor than WFNS grading for patients with low-grade SAH (WFNS grade I/II) undergoing microsurgical clipping. Using 70 years as a cutoff, the study developed a clinically applicable risk evaluation method, dividing the patients into three groups (favourable, intermediate, and poor) based on age and postoperative adverse events.\u003c/p\u003e \u003cp\u003eInitially, this study investigated the association between background factors related to patients, disease, and surgery with favourable outcomes (mRS 0\u0026ndash;2 at discharge). The age at onset was the sole prognostic predictor, highlighting its importance in the prognosis of low-grade SAH. The WFNS grading system has been widely used since its introduction in 1988 to classify prognoses based on the level of consciousness at SAH onset [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e], but some studies have reported no significant prognostic difference between WFNS grades [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. Low-grade SAH (WFNS grades I and II) is generally considered to have a favourable prognosis, but distinguishing between grades can be challenging in older patients with pre-existing cognitive decline. Zijlmans et al. identified age as a background factor associated with unfavourable outcomes (mRS 3\u0026ndash;6) at 6 months after treatment in 132 patients with WFNS grade I aneurysmal SAH [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Conversely, Hori et al. found no background factors, including age, associated with unfavourable outcomes (Glasgow Outcome Scale 1\u0026ndash;3) at discharge in 171 patients with WFNS grade I and II SAH, making the findings controversial [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. These studies included both surgical and endovascular treatments and had heterogeneous cohorts. In our study, age was a stronger prognostic factor for the surgical cohort, suggesting that the higher invasiveness of open surgery may be more impactful on the outcomes of older patients.\u003c/p\u003e \u003cp\u003eUsing the age of 70 years as a partitioning factor, the RPA in this study showed optimal partitioning based on surgical-related complications in patients younger than 70 years and epileptic seizures in those older than 70 years for the prediction of favourable outcomes. This indicates that surgical complications critically affected the mRS of younger patients, while postoperative seizures significantly impacted the outcomes in older patients. The association between poor outcomes and epilepsy at discharge has been reported, suggesting the need for careful surgical techniques to minimise complications [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Prophylactic antiepileptic drug administration to patients with SAH without seizures is debated [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e], but it warrants consideration in older patients due to its potential impact on prognosis. Secondary hydrocephalus is a known predictor of poor outcomes for aneurysmal SAH, and this study confirmed its significance in patients under 70 years with low-grade SAH [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Previous studies have identified age as a risk factor for shunt-dependent hydrocephalus and its correlation with poor outcomes [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The association between hydrocephalus and prognosis in younger patients in this study is noteworthy, although the outcome measurement was mRS at discharge, which may not fully capture long-term recovery.\u003c/p\u003e \u003cp\u003eThis study has a few limitations. Firstly, it was a single-centre retrospective study, and selection bias may have occurred. Secondly, the outcome measurement was mRS at discharge, and long-term follow-up could not be conducted. Thirdly, the classification model has not been validated in a separate cohort. Multicentre prospective studies with long-term follow-up data are needed for further validation.\u003c/p\u003e \u003cp\u003e \u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eConclusion\u003c/span\u003e: Age was a more significant prognostic factor than WFNS grading in patients with WFNS grade I/II aneurysmal subarachnoid haemorrhage undergoing microsurgical clipping. The developed prognostic model with an age cut-off of 70 years and postoperative complications provides a practical tool for predicting outcomes and guiding treatment strategies. In that model, precise microsurgeries with fewer complications determined favourable outcomes beyond the WFNS grade for younger patients, while postoperative intensive seizure management could be meaningful to avoid poor outcomes for older patients.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cu\u003eFunding: None\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eCompeting interests:\u003c/u\u003e The authors report no conflicts of interest concerning the materials or methods used in this study or the findings specified in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAuthor contributions\u003c/u\u003e\u003cu\u003e:\u003c/u\u003e All authors contributed to the study conception and design. Data collection and analysis were performed by Motoyuki Umekawa. The first draft of the manuscript was written by Motoyuki Umekawa and Gakushi Yoshikawa commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eEthics\u003c/u\u003e\u003cu\u003e:\u0026nbsp;\u003c/u\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Institutional Ethics Committee of Showa General Hospital (approval number REC-328).\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eConsent to participate\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eConsent to publish\u003c/u\u003e\u003cu\u003e:\u003c/u\u003e Not applicable\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAdams H, Ban VS, Leinonen V, Aoun SG, Huttunen J, Saavalainen T, Lindgren A, Frosen J, Fraunberg M, Koivisto T, Hernesniemi J, Welch BG, Jaaskelainen JE, Huttunen TJ (2016) Risk of Shunting After Aneurysmal Subarachnoid Hemorrhage: A Collaborative Study and Initiation of a Consortium. Stroke 47:2488\u0026ndash;2496. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/STROKEAHA.116.013739\u003c/span\u003e\u003cspan address=\"10.1161/STROKEAHA.116.013739\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnderson IA, Kailaya-Vasan A, Nelson RJ, Tolias CM (2018) Clipping aneurysms improves outcomes for patients undergoing coiling. J Neurosurg 1\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2017.12.JNS172759\u003c/span\u003e\u003cspan address=\"10.3171/2017.12.JNS172759\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBaldvinsdottir B, Kronvall E, Ronne-Engstrom E, Enblad P, Lindvall P, Aineskog H, Friethriksson S, Klurfan P, Svensson M, Alpkvist P, Hillman J, Eneling J, Nilsson OG (2023) Adverse events associated with microsurgial treatment for ruptured intracerebral aneurysms: a prospective nationwide study on subarachnoid haemorrhage in Sweden. J Neurol Neurosurg Psychiatry 94:575\u0026ndash;580. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/jnnp-2022-330982\u003c/span\u003e\u003cspan address=\"10.1136/jnnp-2022-330982\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrawanski N, Kunze F, Bruder M, Tritt S, Senft C, Berkefeld J, Seifert V, Konczalla J (2017) Subarachnoid Hemorrhage in Advanced Age: Comparison of Patients Aged 70\u0026ndash;79 Years and 80 Years and Older. World Neurosurg 106:139\u0026ndash;144. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2017.06.056\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2017.06.056\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCampi A, Ramzi N, Molyneux AJ, Summers PE, Kerr RS, Sneade M, Yarnold JA, Rischmiller J, Byrne JV (2007) Retreatment of ruptured cerebral aneurysms in patients randomized by coiling or clipping in the International Subarachnoid Aneurysm Trial (ISAT). Stroke 38:1538\u0026ndash;1544. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/STROKEAHA.106.466987\u003c/span\u003e\u003cspan address=\"10.1161/STROKEAHA.106.466987\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChiang VL, Claus EB, Awad IA (2000) Toward more rational prediction of outcome in patients with high-grade subarachnoid hemorrhage. Neurosurgery 46:28\u0026ndash;35 discussion 35\u0026thinsp;\u0026ndash;\u0026thinsp;26\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDaou BJ, Koduri S, Thompson BG, Chaudhary N, Pandey AS (2019) Clinical and experimental aspects of aneurysmal subarachnoid hemorrhage. CNS Neurosci Ther 25:1096\u0026ndash;1112. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/cns.13222\u003c/span\u003e\u003cspan address=\"10.1111/cns.13222\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDarkwah Oppong M, Lohrer L, Wrede KH, Chihi M, Santos AN, Dammann P, Michel A, Rauschenbach L, Said M, Li Y, Frank B, Sure U, Jabbarli R (2023) Reevaluation of risk factors for aneurysmal subarachnoid hemorrhage associated epilepsy. J Neurol Sci 444:120519. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jns.2022.120519\u003c/span\u003e\u003cspan address=\"10.1016/j.jns.2022.120519\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDavies JM, Lawton MT (2014) Advances in open microsurgery for cerebral aneurysms. Neurosurg 74 Suppl 1S7\u0026ndash;16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1227/NEU.0000000000000193\u003c/span\u003e\u003cspan address=\"10.1227/NEU.0000000000000193\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFrontera JA, Fernandez A, Schmidt JM, Claassen J, Wartenberg KE, Badjatia N, Connolly ES, Mayer SA (2009) Defining vasospasm after subarachnoid hemorrhage: what is the most clinically relevant definition? Stroke 40:1963\u0026ndash;1968. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/STROKEAHA.108.544700\u003c/span\u003e\u003cspan address=\"10.1161/STROKEAHA.108.544700\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHart Y, Sneade M, Birks J, Rischmiller J, Kerr R, Molyneux A (2011) Epilepsy after subarachnoid hemorrhage: the frequency of seizures after clip occlusion or coil embolization of a ruptured cerebral aneurysm: results from the International Subarachnoid Aneurysm Trial. J Neurosurg 115:1159\u0026ndash;1168. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2011.6.JNS101836\u003c/span\u003e\u003cspan address=\"10.3171/2011.6.JNS101836\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHirano T, Enatsu R, Iihoshi S, Mikami T, Honma T, Ohnishi H, Mikuni N (2019) Effects of Hemosiderosis on Epilepsy Following Subarachnoid Hemorrhage. Neurol Med Chir (Tokyo) 59:27\u0026ndash;32. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2176/nmc.oa.2018-0125\u003c/span\u003e\u003cspan address=\"10.2176/nmc.oa.2018-0125\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHori S, Masuoka T, Hamada H, Okamoto S, Kubo M, Horie Y, Kuroda S (2023) Walk-In Hospital Admission of Patients with Subarachnoid Hemorrhage: Clinical Presentation and Outcome. World Neurosurg 179:e421\u0026ndash;e427. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2023.08.112\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2023.08.112\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuttunen J, Kurki MI, Fraunberg MVZ, Koivisto T, Ronkainen A, Rinne J, J\u0026auml;\u0026auml;skel\u0026auml;inen JE, K\u0026auml;lvi\u0026auml;inen R, Immonen A (2015) Epilepsy after aneurysmal subarachnoid hemorrhage A population-based, long-term follow-up study. Neurology 84:2229\u0026ndash;2237. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1212/Wnl.0000000000001643\u003c/span\u003e\u003cspan address=\"10.1212/Wnl.0000000000001643\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInagawa T, Kamiya K, Ogasawara H, Yano T (1987) Rebleeding of ruptured intracranial aneurysms in the acute stage. Surg Neurol 28:93\u0026ndash;99. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/0090-3019(87)90079-6\u003c/span\u003e\u003cspan address=\"10.1016/0090-3019(87)90079-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurogi R, Kada A, Ogasawara K, Kitazono T, Sakai N, Hashimoto Y, Shiokawa Y, Miyachi S, Matsumaru Y, Iwama T, Tominaga T, Onozuka D, Nishimura A, Arimura K, Kurogi A, Ren N, Hagihara A, Nakaoku Y, Arai H, Miyamoto S, Nishimura K, Iihara K (2020) Effects of case volume and comprehensive stroke center capabilities on patient outcomes of clipping and coiling for subarachnoid hemorrhage. J Neurosurg 134:929\u0026ndash;939. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2019.12.JNS192584\u003c/span\u003e\u003cspan address=\"10.3171/2019.12.JNS192584\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKurogi R, Kada A, Ogasawara K, Nishimura K, Kitazono T, Iwama T, Matsumaru Y, Sakai N, Shiokawa Y, Miyachi S, Kuroda S, Shimizu H, Yoshimura S, Osato T, Horie N, Nagata I, Nozaki K, Date I, Hashimoto Y, Hoshino H, Nakase H, Kataoka H, Ohta T, Fukuda H, Tamiya N, Kurogi AI, Ren N, Nishimura A, Arimura K, Shimogawa T, Yoshimoto K, Onozuka D, Ogata S, Hagihara A, Saito N, Arai H, Miyamoto S, Tominaga T, Iihara K, Collaborators JAS (2023) National trends in the outcomes of subarachnoid haemorrhage and the prognostic influence of stroke centre capability in Japan: retrospective cohort study. BMJ Open 13:e068642. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/bmjopen-2022-068642\u003c/span\u003e\u003cspan address=\"10.1136/bmjopen-2022-068642\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLantigua H, Ortega-Gutierrez S, Schmidt JM, Lee K, Badjatia N, Agarwal S, Claassen J, Connolly ES, Mayer SA (2015) Subarachnoid hemorrhage: who dies, and why? Crit Care 19. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s13054-015-1036-0\u003c/span\u003e\u003cspan address=\"10.1186/s13054-015-1036-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLe VT, Nguyen AM, Nguyen PL (2024) Risk Factors for In-Hospital Seizure and New-Onset Epilepsy in Coiling and Clipping Treatment of Aneurysmal Subarachnoid Hemorrhage. World Neurosurg 184:e460\u0026ndash;e467. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2024.01.146\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2024.01.146\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMacdonald RL, Pluta RM, Zhang JH (2007) Cerebral vasospasm after subarachnoid hemorrhage: the emerging revolution. Nat Clin Pract Neurol 3:256\u0026ndash;263. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/ncpneuro0490\u003c/span\u003e\u003cspan address=\"10.1038/ncpneuro0490\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMayberg MR, Batjer HH, Dacey R, Diringer M, Haley EC, Heros RC, Sternau LL, Torner J, Adams HP Jr., Feinberg W et al (1994) Guidelines for the management of aneurysmal subarachnoid hemorrhage. A statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke 25:2315\u0026ndash;2328. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/01.str.25.11.2315\u003c/span\u003e\u003cspan address=\"10.1161/01.str.25.11.2315\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMijiti M, Mijiti P, Axier A, Amuti M, Guohua Z, Xiaojiang C, Kadeer K, Xixian W, Geng D, Maimaitili A (2016) Incidence and Predictors of Angiographic Vasospasm, Symptomatic Vasospasm and Cerebral Infarction in Chinese Patients with Aneurysmal Subarachnoid Hemorrhage. PLoS ONE 11:e0168657. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pone.0168657\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0168657\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMocco J, Ransom ER, Komotar RJ, Schmidt JM, Sciacca RR, Mayer SA, Connolly ES Jr (2006) Preoperative prediction of long-term outcome in poor-grade aneurysmal subarachnoid hemorrhage. Neurosurgery 59:529\u0026ndash;538; discussion 529\u0026ndash;538. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1227/01.NEU.0000228680.22550.A2\u003c/span\u003e\u003cspan address=\"10.1227/01.NEU.0000228680.22550.A2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMolyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, Holman R, International Subarachnoid Aneurysm Trial Collaborative G (2002) International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet 360:1267\u0026ndash;1274. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/s0140-6736(02)11314-6\u003c/span\u003e\u003cspan address=\"10.1016/s0140-6736(02)11314-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakashima S, Nishibayashi H, Yako R, Ishii M, Toki N, Tomobuchi M, Nakai T, Yamoto H, Nakanishi Y, Nakao N (2024) Factors Associated with Early and Late Seizure Related to Aneurysmal Subarachnoid Hemorrhage. Neurol Med Chir (Tokyo) 64:123\u0026ndash;130. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2176/jns-nmc.2023-0201\u003c/span\u003e\u003cspan address=\"10.2176/jns-nmc.2023-0201\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNatarajan SK, Sekhar LN, Ghodke B, Britz GW, Bhagawati D, Temkin N (2008) Outcomes of ruptured intracranial aneurysms treated by microsurgical clipping and endovascular coiling in a high-volume center. AJNR Am J Neuroradiol 29:753\u0026ndash;759. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3174/ajnr.A0895\u003c/span\u003e\u003cspan address=\"10.3174/ajnr.A0895\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNguyen TA, Vu LD, Mai TD, Dao CX, Ngo HM, Hoang HB, Do SN, Nguyen HT, Pham DT, Nguyen MH, Nguyen DN, Vuong HTT, Vu HD, Nguyen DD, Nguyen LQ, Dao PV, Vu TD, Nguyen DT, Tran TA, Pham TQ, Van Nguyen C, Nguyen AD, Luong CQ (2023) Predictive validity of the prognosis on admission aneurysmal subarachnoid haemorrhage scale for the outcome of patients with aneurysmal subarachnoid haemorrhage. Sci Rep 13:6721. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41598-023-33798-5\u003c/span\u003e\u003cspan address=\"10.1038/s41598-023-33798-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOka F, Sadeghian H, Yaseen MA, Fu B, Kura S, Qin T, Sakadzic S, Sugimoto K, Inoue T, Ishihara H, Nomura S, Suzuki M, Ayata C (2022) Intracranial pressure spikes trigger spreading depolarizations. Brain 145:194\u0026ndash;207. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/brain/awab256\u003c/span\u003e\u003cspan address=\"10.1093/brain/awab256\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePaisan GM, Ding D, Starke RM, Crowley RW, Liu KC (2018) Shunt-Dependent Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage: Predictors and Long-Term Functional Outcomes. Neurosurgery 83:393\u0026ndash;402. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/neuros/nyx393\u003c/span\u003e\u003cspan address=\"10.1093/neuros/nyx393\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePluta RM, Hansen-Schwartz J, Dreier J, Vajkoczy P, Macdonald RL, Nishizawa S, Kasuya H, Wellman G, Keller E, Zauner A, Dorsch N, Clark J, Ono S, Kiris T, Leroux P, Zhang JH (2009) Cerebral vasospasm following subarachnoid hemorrhage: time for a new world of thought. Neurol Res 31:151\u0026ndash;158. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1179/174313209X393564\u003c/span\u003e\u003cspan address=\"10.1179/174313209X393564\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRosen DS, Macdonald RL (2005) Subarachnoid hemorrhage grading scales: a systematic review. Neurocrit Care 2:110\u0026ndash;118. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1385/NCC:2:2\u003c/span\u003e\u003cspan address=\"10.1385/NCC:2:2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSano H, Satoh A, Murayama Y, Kato Y, Origasa H, Inamasu J, Nouri M, Cherian I, Saito N, members of the 38 registered i, Disease WC, Treatment C (2015) Modified World Federation of Neurosurgical Societies subarachnoid hemorrhage grading system. World Neurosurg 83:801\u0026ndash;807. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2014.12.032\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2014.12.032\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTanno Y, Homma M, Oinuma M, Kodama N, Ymamoto T (2007) Rebleeding from ruptured intracranial aneurysms in North Eastern Province of Japan. A cooperative study. J Neurol Sci 258:11\u0026ndash;16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jns.2007.01.074\u003c/span\u003e\u003cspan address=\"10.1016/j.jns.2007.01.074\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTeasdale GM, Drake CG, Hunt W, Kassell N, Sano K, Pertuiset B, De Villiers JC (1988) A universal subarachnoid hemorrhage scale: report of a committee of the World Federation of Neurosurgical Societies. J Neurol Neurosurg Psychiatry 51:1457. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/jnnp.51.11.1457\u003c/span\u003e\u003cspan address=\"10.1136/jnnp.51.11.1457\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTodd MM (2020) Erratum. Acute postoperative neurological deterioration associated with surgery for ruptured intracranial aneurysm: incidence, predictors, and outcomes. J Neurosurg 132:2009. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2020.1.JNS111277a\u003c/span\u003e\u003cspan address=\"10.3171/2020.1.JNS111277a\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUmekawa M, Yoshikawa G (2023) Impact of ventriculo-cisternal irrigation on prevention of delayed cerebral infarction in aneurysmal subarachnoid hemorrhage: a single-center retrospective study and literature review. Neurosurg Rev 47:6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s10143-023-02241-8\u003c/span\u003e\u003cspan address=\"10.1007/s10143-023-02241-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003evan der Schaaf I, Algra A, Wermer M, Molyneux A, Clarke M, van Gijn J, Rinkel G (2005) Endovascular coiling versus neurosurgical clipping for patients with aneurysmal subarachnoid haemorrhage. Cochrane Database Syst Rev:CD003085. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/14651858.CD003085.pub2\u003c/span\u003e\u003cspan address=\"10.1002/14651858.CD003085.pub2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003evan Donkelaar CE, Bakker NA, Veeger NJ, Uyttenboogaart M, Metzemaekers JD, Eshghi O, Mazuri A, Foumani M, Luijckx GJ, Groen RJ, van Dijk JM (2017) Prediction of outcome after subarachnoid hemorrhage: timing of clinical assessment. J Neurosurg 126:52\u0026ndash;59. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3171/2016.1.JNS152136\u003c/span\u003e\u003cspan address=\"10.3171/2016.1.JNS152136\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVergouwen MDI, Vermeulen M, van Gijn J, Rinkel GJE, Wijdicks EF, Muizelaar JP, Mendelow AD, Juvela S, Yonas H, Terbrugge KG, Macdonald RL, Diringer MN, Broderick JP, Dreier JP, Roos YBWEM (2010) Definition of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage as an Outcome Event in Clinical Trials and Observational Studies Proposal of a Multidisciplinary Research Group. Stroke 41:2391\u0026ndash;2395. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/Strokeaha.110.589275\u003c/span\u003e\u003cspan address=\"10.1161/Strokeaha.110.589275\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWaldron JS, Halbach VV, Lawton MT (2009) Microsurgical management of incompletely coiled and recurrent aneurysms: trends, techniques, and observations on coil extrusion. Neurosurgery 64:301\u0026ndash;315 discussion 315\u0026thinsp;\u0026ndash;\u0026thinsp;307. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1227/01.NEU.0000335178.15274.B4\u003c/span\u003e\u003cspan address=\"10.1227/01.NEU.0000335178.15274.B4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXie Z, Hu X, Zan X, Lin S, Li H, You C (2017) Predictors of Shunt-dependent Hydrocephalus After Aneurysmal Subarachnoid Hemorrhage? A Systematic Review and Meta-Analysis. World Neurosurg 106:844\u0026ndash;860e846. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2017.06.119\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2017.06.119\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYue Q, Liu Y, Leng B, Xu B, Gu Y, Chen L, Zhu W, Mao Y (2016) A Prognostic Model for Early Post-Treatment Outcome of Elderly Patients With Aneurysmal Subarachnoid Hemorrhage. World Neurosurg 95:253\u0026ndash;261. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2016.08.020\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2016.08.020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZafar SF, Rosenthal ES, Postma EN, Sanches P, Ayub MA, Rajan S, Kim JA, Rubin DB, Lee H, Patel AB, Hsu J, Patorno E, Westover MB (2022) Antiseizure Medication Treatment and Outcomes in Patients with Subarachnoid Hemorrhage Undergoing Continuous EEG Monitoring. Neurocrit Care 36:857\u0026ndash;867. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s12028-021-01387-x\u003c/span\u003e\u003cspan address=\"10.1007/s12028-021-01387-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZijlmans JL, Coert BA, van den Berg R, Sprengers MES, Majoie C, Vandertop WP, Verbaan D (2018) Unfavorable Outcome in Patients with Aneurysmal Subarachnoid Hemorrhage WFNS Grade I. World Neurosurg 118:e217\u0026ndash;e222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.wneu.2018.06.157\u003c/span\u003e\u003cspan address=\"10.1016/j.wneu.2018.06.157\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"neurosurgical-review","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nrev","sideBox":"Learn more about [Neurosurgical Review](https://www.springer.com/journal/10143)","snPcode":"10143","submissionUrl":"https://submission.nature.com/new-submission/10143/3","title":"Neurosurgical Review","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"aneurysm, age-dependent, microsurgical clipping, recursive partitioning analysis, subarachnoid haemorrhage, World Federation of Neurosurgical Societies grade","lastPublishedDoi":"10.21203/rs.3.rs-4922161/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4922161/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eThis study aimed to evaluate age as a prognostic factor and develop a comprehensive prognostic model for patients undergoing clipping surgery for World Federation of Neurosurgical Societies (WFNS) grade I/II aneurysmal subarachnoid haemorrhage (SAH).\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe retrospectively investigated 188 patients with WFNS grade I/II SAH who underwent microsurgical clipping at our institute between December 2010 and January 2020. The data of 176 patients (75 with grade I and 101 with grade II) were analysed. Data on patient demographics, aneurysm characteristics, SAH factors, surgical details, and clinical outcomes were collected. Prognostic factors were assessed using bivariate and multivariable logistic regression analyses, and recursive partitioning analysis.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eFavourable outcomes (mRS 0\u0026ndash;2) were observed in 76% of patients. Age, a significant negative prognostic factor in multivariable analysis (odds ratio 0.55, 95% confidence interval 0.40\u0026ndash;0.76, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), was cutoff at 70 years by the receiver operating characteristic curve. Patients aged\u0026thinsp;\u0026le;\u0026thinsp;70 years had significantly better outcomes than those aged\u0026thinsp;\u0026gt;\u0026thinsp;70 years (84% vs. 46%, respectively; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Epileptic seizures were significantly associated with poor outcomes in older adults (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). A prognostic model (favourable, intermediate, and poor) based on age and postoperative adverse events showed significantly different outcomes between age groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eAge was a stronger prognostic factor than WFNS grading for patients with grade I/II SAH undergoing microsurgical clipping. For patients aged\u0026thinsp;\u0026le;\u0026thinsp;70 years, precise microsurgeries with fewer complications were associated with favourable outcomes beyond WFNS grade. For older patients, postoperative intensive seizure management may prevent poor outcomes.\u003c/p\u003e","manuscriptTitle":"Impact of age on surgical outcomes for World Federation of Neurosurgical Societies grade I and II aneurysmal subarachnoid haemorrhage: a novel prognostic model using recursive partitioning analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-10-15 04:56:24","doi":"10.21203/rs.3.rs-4922161/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-10-03T12:12:52+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-10-02T07:41:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"250132275553116149152971012960622916627","date":"2024-09-22T09:18:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"141836482357846857051229620287451834168","date":"2024-09-19T10:50:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-18T20:57:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"110053660939240754233851735019422911701","date":"2024-09-18T11:29:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"57569678489140520705030084673772367986","date":"2024-08-29T06:49:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-28T09:31:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-28T09:30:07+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-19T13:03:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Neurosurgical Review","date":"2024-08-16T03:25:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"neurosurgical-review","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nrev","sideBox":"Learn more about [Neurosurgical Review](https://www.springer.com/journal/10143)","snPcode":"10143","submissionUrl":"https://submission.nature.com/new-submission/10143/3","title":"Neurosurgical Review","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"7c2be556-98b1-4ee3-98b1-c61274afa45b","owner":[],"postedDate":"October 15th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-11-04T16:23:56+00:00","versionOfRecord":{"articleIdentity":"rs-4922161","link":"https://doi.org/10.1007/s10143-024-03067-8","journal":{"identity":"neurosurgical-review","isVorOnly":false,"title":"Neurosurgical Review"},"publishedOn":"2024-10-30 16:13:11","publishedOnDateReadable":"October 30th, 2024"},"versionCreatedAt":"2024-10-15 04:56:24","video":"","vorDoi":"10.1007/s10143-024-03067-8","vorDoiUrl":"https://doi.org/10.1007/s10143-024-03067-8","workflowStages":[]},"version":"v1","identity":"rs-4922161","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4922161","identity":"rs-4922161","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}