Determinants of Neurological Complications after Degenerative Spine Surgery: a Nationwide Cohort Study based on the French SNDS Database

Determinants of Neurological Complications after Degenerative Spine Surgery: a Nationwide Cohort Study based on the French SNDS Database | 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 Determinants of Neurological Complications after Degenerative Spine Surgery: a Nationwide Cohort Study based on the French SNDS Database Raphaël Garcia, Julien Bezin, Paul Roblot, Pierre Grobost, Jean-Rodolphe Vignes This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8418831/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 9 You are reading this latest preprint version Abstract Purpose – In France, around 160,000 spine surgery procedures are performed yearly for spinal deformities or degenerative, tumoral, or traumatic spine pathologies. This study aimed to describe neurological complications following spine surgery for degenerative pathology and identify their determinants at the national level. Methods – Using the French national health insurance system database (Système National des Données de Santé, SNDS), a cohort was constituted including all French patients aged 18 and older in 2018 who underwent their first surgery for degenerative spine pathology in that year. Complications were identified through hospital diagnoses and surgical procedures within the following 12 months. Patient characteristics and complications were described. A cause-specific Cox model was used to identify the determinants of spine surgery complications. Results – A total of 79,151 patients were identified with incident spine surgery for degenerative pathology (mean patient age 55 years, standard deviation 15; 51.0% women) and 14.8% of them had one or more complications within one year after surgery. Determinants associated with the occurrence of complications were female sex (HR = 1.05, 95%CI=[1.01;1.09]), age > 65 (1.55 [1.46;1.64]), length of stay for initial surgery > 5 days (2.73 [2.58;2.89]), lumbar and cervical spine levels (1.38 [1.13;1.68]), overweight or obesity (1.08 [1.02;1.15]), public institution (1.07 [1.03;1.12]) and previous consultation for the pathology (1.43 [1.38;1.49]). Conclusion – Almost one in six patients with degenerative spine pathology develops a complication after surgery. Main determinants of postoperative complications appear to be associated with disease severity and comorbidities. spine surgery degenerative pathology neurological complications Figures Figure 1 Figure 2 Figure 3 BACKGROUND Degenerative spinal disorders represent the most frequent causes of spinal disease, accounting for nearly 70% of cases.[ 1 ] In this context, most surgical procedures aim to achieve spinal stabilization and/or to relieve compression of neural structures.[ 2 ] Following these procedures, patients may experience complications. A complication is defined as an undesirable secondary event occurring during or after surgery that may worsen the patient's condition, prolong the duration of the illness or recovery, or require additional treatment. Complications can be major or minor, or classified using grades, and may necessitate further intervention. They include infectious, respiratory, pain-related, neurological events, or any deviation from the perioperative course.[ 3 – 5 ] For patients undergoing surgery for spinal disorders, the main preoperative concerns include the potential long-term impact of surgery on quality of life (QoL).[ 6 ] Given the potentially irreversible consequences of perioperative neurological events on functional outcomes and QoL, epidemiological data on their occurrence are essential to provide accurate information to patients, evaluate clinical practices, and identify areas to improve. Neurological complication after spinal surgery are variably defined but generally encompass any impairment of the central or peripheral nervous system, or their coverings, related to the operated site.[ 7 , 8 ] These include nerve roots compressions or injury, as well as meningeal damage.[ 9 – 12 ] Such complications may manifest as pain, impairment of motor or sensory deficits, or cognitive impairment, potentially leading to persistent disability. Neurological complications may occur intraoperatively, in the early postoperative period (within the first month), before or after hospital discharge.[ 13 ] Rates of postoperative complications following spinal surgery have been previously reported using cohorts or reviews, often stratified by underlying pathology or surgical technique.[ 8 , 10 , 13 – 15 ] However, available data in Europe are described from selected populations, limiting their generalizability. To date, no nationwide, population-based study has comprehensively assessed the incidence and determinants of neurological complications following spinal surgery for degenerative disease in Europe. Using the French National Health Insurance System database (Système National des Données de Santé, SNDS ), we sought to quantify complication rates at the national level, and to identify patient-, disease-, and procedure-related determinants. METHODS Study design and database This cohort study was based on data from the French National Health Insurance System database (Système National des Données de Santé, SNDS), which records healthcare reimbursements for 98.8% of the French population (63 million individuals in 2018).[ 16 ] The SNDS contains comprehensive information on demographic characteristics, drug reimbursements, outpatient healthcare reimbursements, hospital admission, and medical data. Diagnoses are coded using the International Classification of Diseases, 10th Revision (ICD-10), and medical and surgical procedures are recorded according to the French common classification of medical procedures (Classification Commune des Actes Médicaux, CCAM). Further details on the French medico-administrative databases have been previously described.[ 17 ] Given the disruption to healthcare delivery caused by the COVID-19 pandemic and the resulting incompleteness of post-pandemic data, this study was restricted to the period preceding 2020 . Neither ethics committee approval nor informed consent were required for this observational study based on French medico-administrative databases because of the anonymous nature of the data, by agreement of the French Data Protection Supervisor Authority (Commission Nationale de l’Informatique et des Libertés - CNIL). Study population Patients who underwent spine surgery in 2018 (codes were described in Table S1 in the Supplement), without spine surgery in the preceding year and aged 18 or older were included. To consider only the degenerative causes, patients with trauma or cancer diagnoses, or those treated with anticancer drugs in the 6 months before spine surgery were excluded. Considering the lack of data for patients not affiliated to the general health insurance regimen, they were excluded. Events of interest Intraoperative and postoperative neurological complications were identified through hospital diagnosis codes and medical procedures in the year after inclusion (Table S1 ). The corresponding codes were selected by a multidisciplinary committee including neurosurgeon, spine orthopaedic surgeon, epidemiologist and data-scientist. Complications occurring within the first 30 days following surgery were defined as early.[ 18 – 20 ] Only the first occurring complication was classified in the results. Codes corresponding to a common postoperative evolution of the pathology were excluded. Period of interest Patients were followed for one year from the date of their first spine surgery for degenerative pathology in 2018. Patient follow-up was censored at postoperative day 365 or at the date of death when applicable. Analysis Descriptive statistics characterized the study population by age at inclusion, sex, overweight or obesity status, type of hospital (private or public) where the spine surgery was performed, hospital stay duration, delay between surgery and first complication, and history of previous admissions for degenerative pathologies in the 5 years before inclusion. Medical procedures and diagnoses (at inclusion or as complication) were described using frequency distribution and absolute number. Complications incidence over time was described using the cumulative incidence curve with the Aalen-Johansen estimator. Multivariable cause-specific Cox regression identified patient characteristics associated with complication during the year following the surgery. The proportional hazard assumption was checked for each covariate tested in the model. All covariates in the model were categorical or categorised. Analyses were performed using SAS Enterprise Guide software (version 8.3, SAS Institute, North Carolina, USA) and R (version 4.3.1, R Foundation for Statistical Computing, Vienna, Austria). RESULTS Description of patients Based on the 63 million French people in the database in 2018, 79,151 patients were identified with an incident spine surgery for degenerative pathology (Fig. 1 ). About a quarter of patients had an history of hospitalisation for degenerative pathologies before inclusion (29.5%) (Table 1 ). Mean patient age at time of surgery was 55 years (SD 15); with 51.0% women and 9.4% overweight or obesity. Procedures at inclusion were mostly related to the lumbar level (80.7%). Average hospitalization duration for surgery was 4.4 days (SD 4.1) and 68.6% occurred in private healthcare institution. Table 1 Characteristics of patients following spine surgery for degenerative spine pathology in 2018, France. Population (N = 79,151) Women, n (%) 40,381 (51.0) Age (years), mean (SD) 54.9 (15.5) Spine level of initial surgery, n (%) Lumbar 63,897 (80.7) Cervical 9,028 (11.4) Lumbar and cervical 479 (0.6) Unspecified 5,747 (7.3) History of hospitalisation for degenerative pathologies, n (%) 23,308 (29.5) Overweight or obesity, n (%) 7,439 (9.4) Private healthcare facility, n (%) 54,332 (68.6) Length of stay (days), mean (SD) 4.4 (4.1) Abbreviations: SD: Standard Deviation Incidence of complications The cumulative incidence of postoperative neurological complications sharply increased to 7.6% within the first 30 days following initial surgery, and kept rising steadily afterwards to reach 14.7% at one-year (Fig. 2 ). First identified complications were more frequently related to lumbar spine than cervical spine or non-defined region: 13.8% of the complications concerned “Spinal stenosis, lumbar region”, 15.8% “Nerve roots and plexuses compressions during intervertebral disc pathology”, 3.2% “Lumbar or lumbosacral total bilateral laminectomy with arthrectomy, via posterior approach” and 3.1% “Debridement of postoperative spinal and/or paravertebral infectious epidural lesion [sepsis], via direct approach” (Fig. 3 ). The description of complications by age group shows little difference apart from the complications of “Spinal stenosis, lumbar region” and “Nerve roots and plexuses compressions during other dorsopathies” for which the frequency increased with age, and compression “Nerve roots and plexuses compressions during intervertebral disc pathology” which decreases with age (Figure S1 in the Supplement). Determinants of complications Multivariable cause-specific Cox regression showed a significant but non-linear effect of age on the risk of complications (aHR = 1.55 95%CI [1.46;1.64] for patients aged > 65 vs ≤ 40) and an association with the initial hospital stay duration (2.73 [2.58;2.89] for stay > 5 days vs ≤ 2 days) (Table 2 ). The major determinant of postoperative neurological complications was history of spine degenerative pathology hospitalisation (1.43 [1.38;1.49]). Moreover, overweight or obesity (1.08 [1.02;1.15]), public hospitalization at initial surgery (1.07 [1.03–1.10]) and female sex (1.05 [1.01;1.08]) were slightly associated with higher complications risks. Table 2. Risk of complication at one-year post-surgery (cause-specific Cox regression) aHR 95% CI p Sex (female vs male) 1.05 1.01-1.08 0.008 Age at initial surgery (vs 40 years and younger) 41-50 51-65 >65 1.13 1.22 1.55 1.06-1.21 1.15-1.30 1.46-1.64 <10 -3 Spine level of initial surgery (vs lumbar) Cervical Cervical and lumbar Cervical and unspecified Lumbar and unspecified Lumbar and cervical and unspecified Unspecified 0.98 1.38 1.39 1.00 0.88 1.04 0.91-1.05 1.13-1.68 1.18-1.63 0.95-1.06 0.28-2.72 0.97-1.12 <10 -3 History of previous hospitalization for degenerative pathologies (yes vs no) 1.43 1.38-1.49 5 days 1.01 1.20 2.73 0.94-1.08 1.13-1.27 2.58-2.89 <10 -3 Abbreviations: aHR: adjusted Hazard Ratio; 95%CI: 95% Confidence Interval DISCUSSION This nationwide French cohort including more than 79,000 patients undergoing surgery for degenerative spine disorders showed that nearly one in six experienced a neurological complication within the year following surgery. The risk of complications was higher among older patients, women, individuals with overweight or obesity, those with a history of hospitalization for degenerative spinal disease, in cases involving cervical or multilevel procedures, in those with prolonged initial hospital stay, and in patients treated in public institutions. These findings highlight the multifactorial nature of postoperative neurological risk and provide the first national overview of neurological complications following surgery for degenerative spinal disorders in France. When compared with the international literature, our findings are broadly consistent, although substantial variability exists across regions, study designs, and outcomes definitions. In the United States, analyses of large administrative datasets have reported 30-day neurological complication rates of approximatively 5%, which are substantially lower than the one-year cumulative incidence observed in our study.(16) A multicentre study conducted in Washington state (USA) including 24,882 patients who underwent lumbar surgery for degenerative spine disorders between 1990 and 1993 reported a cumulative reoperation incidence of 19% at 11 years of follow-up.(20) Similarly, a multicentre study from the Province of Ontario (Canada) including 4,722 patients undergoing first-time spinal surgery between 1900 and 1991 reported a reoperations rate of 9.5%, with a maximum follow-up of 4 years.(21) Multicenter studies from Latin America and North America focusing on spinal and cervical deformities have reported complication rates ranging from 9% to 19%, depending on follow-up duration and procedural complexity.(17,18) In Europe, a nationwide Norwegian study used the Global Perceived Effect scale to measure the patients’ perception of their own health after surgery for degenerative myelopathy at 1 year. It revealed a 16% rate of patients measuring their health as slightly worse, much worse or worse than ever.(19) European registry data reported perioperative complication rates between 10% and 17%(22), which are comparable to those observed in the present study. These discrepancies underscore the influence of population characteristics, surgical indications, follow-up duration, and outcome definitions. Nonetheless, they consistently indicate that neurological complications remain frequent and clinically meaningful across different healthcare systems. Several factors may explain the determinants identified in our analysis. The slightly higher risk observed among women may be related to skeletal fragility, particularly postmenopausal osteoporosis, which increases vulnerability to surgical stress on the spine. However, this interpretation remains speculative and should be regarded as a hypothesis for future research rather than a firm conclusion. Age also emerged as a strong predictor, consistent with the accumulation of comorbidities, frailty, and reduced physiological reserve in older patients. The association with overweight or obesity is biologically plausible, as excess body mass increases mechanical loading on the spine, complicates surgical exposure, and may predispose to impaired wound healing. Multilevel procedures, by prolonging operative time and tissue exposure, logically entail a higher risk of neurological injury. A prolonged initial hospital stay is more likely to reflect perioperative complications or poorer baseline health status, and could be interpreted as a marker of increased risk rather than a direct causal factor. Finally, the slightly higher complication rates observed in public hospitals may be linked to patient selection, with more complex or severe cases preferentially referred to these institutions, or to organizational and structural variations in care delivery. This study has several limitations that should be acknowledged. The use of the SNDS database precludes access to detailed clinical information such as preoperative neurological status, imaging findings, smoking history, or bone mineral density, nor to lifestyle or socioeconomic factors that may influence postoperative outcomes. Moreover, the one-year follow-up may underestimate the incidence of late neurological complications, particularly those related to pseudarthrosis, which can lead to delayed to nerve root compression.[ 21 – 23 ] The retrospective design limits causal inference, and coding inaccuracies are possible despite careful validation by experienced spine surgeons. Nevertheless, the large sample size, nationwide coverage, and standardized coding of diagnoses and procedures provide robust population-based estimates and support the generalizability of our findings to the French population. From a clinical perspective, these findings underscore the importance of preoperative identification of patient subgroups at increased risk of neurological complications following spine surgery. Particular attention should be paid to older and female patients, individuals with overweight or obesity, and those requiring multilevel procedures, as targeted perioperative optimization may help mitigate risk. Enhanced monitoring and tailored rehabilitation strategies in these populations could contribute to reducing complication rates and improving long-term outcomes. At a broader level, the findings underline the value of nationwide health databases in guiding public health decisions and supporting the development of evidence-based clinical practice guidelines in spine surgery. CONCLUSION Neurological complications within the year following spine surgery in patients with degenerative spinal disorders occur in approximately one out of six patients. This risk is influenced by preoperative and perioperative characteristics, including, sex, age, length of the initial hospital stays, body mass index, spinal level and extent of the index procedure, type of healthcare facility, and prior hospitalization for degenerative spinal disease. These determinants are relevant when considering surgical management and planning postoperative follow-up in patients undergoing spine surgery for degenerative pathology. Declarations Data sharing statement No additional data available by author (French law to access SNDS www.health-data-hub.fr ). Conflict of interest disclosures Co-authors have no conflict of interest. Ethic approval By agreement of the French Data Protection Supervisory Authority (CNIL), neither ethics committee approval nor informed consent were required for this observational study based on anonymized French medico administrative databases. Funding Grant of the SFCR (French Society of spine surgery). Author Contribution R.G. and J.B. conducted the statistical analyses and wrote the main manuscript text and E.F. prepared figures 1-3. All authors reviewed the manuscript Acknowledgement The authors would like to thank the French Society of Spinal Surgery for funding this Biostatistics internship, and Prof. Antoine Pariente for his critical review of the manuscript. Data Availability The French database (Système National des Données de Santé) that support the findings of this study are available from www.health-data-hub.fr, but restrictions apply to the availability of these data, and so are not publicly available. The data are, however, available upon request and with the permission of the French Ministry of Health. References Ravindra VM, Senglaub SS, Rattani A et al (2018) Degenerative Lumbar Spine Disease: Estimating Global Incidence and Worldwide Volume. 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05:36:30","extension":"xml","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":68397,"visible":true,"origin":"","legend":"","description":"","filename":"274af268b1914222af2f49cad70de4231structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/4d27e1bb2adf8e9d40c54406.xml"},{"id":100361294,"identity":"dce679bd-3b02-4c77-9ecf-01f29088f24b","added_by":"auto","created_at":"2026-01-16 07:44:51","extension":"html","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":77751,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/b151496e768787cd7dee3310.html"},{"id":100005951,"identity":"2ed9a409-bc59-4621-93ba-3bab6ca7087e","added_by":"auto","created_at":"2026-01-12 05:36:30","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":78192,"visible":true,"origin":"","legend":"\u003cp\u003eStudy flow-chart\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/c85dd36cc7bcba42e6ff6d59.png"},{"id":100005953,"identity":"8cac07e9-f774-46f0-bebc-d11d685f561c","added_by":"auto","created_at":"2026-01-12 05:36:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":29605,"visible":true,"origin":"","legend":"\u003cp\u003eProbability of a complication at one year (Aalen-Johansen estimator)\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/d02d3d54e765964e3c048e83.png"},{"id":100360812,"identity":"699d885c-4a4b-4b0a-8747-abb8bd3cc299","added_by":"auto","created_at":"2026-01-16 07:43:56","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":80356,"visible":true,"origin":"","legend":"\u003cp\u003eDescription of first complications at one-year post-surgery according to diagnosis and procedure codes. The 5 levels of the concentric circle correspond to the successive levels of precision of the codes used. The size of each cell is proportional to the proportion represented by the complication among all the complication. The first level represented the proportion of complications identified through procedure (CCAM codes) in black or diagnosis (ICD-10 codes) in grey. The second level represented the proportion of complications identified according to the first level of the classification: therapeutic procedures on the spinal central nervous system (CCAM chapter 1.3) in red, therapeutic procedures on the spinal column (CCAM chapter 12.2) in green, diseases of the nervous system (ICD-10 code G) in orange, and diseases of the musculoskeletal system and connective tissue (ICD-10 code M) in blue. The following levels represented the different levels of precision of the codes up to the most precise level.\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/9e86b0411c940e895da5cb85.png"},{"id":100380862,"identity":"8669c2ce-7f5f-46c0-a7ad-185333fd74a4","added_by":"auto","created_at":"2026-01-16 10:36:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":849009,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/c1c96d64-a923-40f6-a31c-a59a1aca44f9.pdf"},{"id":100361333,"identity":"5098b675-7c70-4771-a444-258436dca2ce","added_by":"auto","created_at":"2026-01-16 07:44:58","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":141800,"visible":true,"origin":"","legend":"","description":"","filename":"SUPPLEMENT.docx","url":"https://assets-eu.researchsquare.com/files/rs-8418831/v1/1238a99bb7f2cf3e6bb83b65.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Determinants of Neurological Complications after Degenerative Spine Surgery: a Nationwide Cohort Study based on the French SNDS Database","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eDegenerative spinal disorders represent the most frequent causes of spinal disease, accounting for nearly 70% of cases.[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] In this context, most surgical procedures aim to achieve spinal stabilization and/or to relieve compression of neural structures.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Following these procedures, patients may experience complications. A complication is defined as an undesirable secondary event occurring during or after surgery that may worsen the patient's condition, prolong the duration of the illness or recovery, or require additional treatment. Complications can be major or minor, or classified using grades, and may necessitate further intervention. They include infectious, respiratory, pain-related, neurological events, or any deviation from the perioperative course.[\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eFor patients undergoing surgery for spinal disorders, the main preoperative concerns include the potential long-term impact of surgery on quality of life (QoL).[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] Given the potentially irreversible consequences of perioperative neurological events on functional outcomes and QoL, epidemiological data on their occurrence are essential to provide accurate information to patients, evaluate clinical practices, and identify areas to improve.\u003c/p\u003e \u003cp\u003eNeurological complication after spinal surgery are variably defined but generally encompass any impairment of the central or peripheral nervous system, or their coverings, related to the operated site.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] These include nerve roots compressions or injury, as well as meningeal damage.[\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] Such complications may manifest as pain, impairment of motor or sensory deficits, or cognitive impairment, potentially leading to persistent disability. Neurological complications may occur intraoperatively, in the early postoperative period (within the first month), before or after hospital discharge.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eRates of postoperative complications following spinal surgery have been previously reported using cohorts or reviews, often stratified by underlying pathology or surgical technique.[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] However, available data in Europe are described from selected populations, limiting their generalizability. To date, no nationwide, population-based study has comprehensively assessed the incidence and determinants of neurological complications following spinal surgery for degenerative disease in Europe. Using the French National Health Insurance System database (Syst\u0026egrave;me National des Donn\u0026eacute;es de Sant\u0026eacute;, \u003cem\u003eSNDS\u003c/em\u003e), we sought to quantify complication rates at the national level, and to identify patient-, disease-, and procedure-related determinants.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and database\u003c/h2\u003e \u003cp\u003eThis cohort study was based on data from the French National Health Insurance System database (Syst\u0026egrave;me National des Donn\u0026eacute;es de Sant\u0026eacute;, SNDS), which records healthcare reimbursements for 98.8% of the French population (63\u0026nbsp;million individuals in 2018).[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] The SNDS contains comprehensive information on demographic characteristics, drug reimbursements, outpatient healthcare reimbursements, hospital admission, and medical data. Diagnoses are coded using the International Classification of Diseases, 10th Revision (ICD-10), and medical and surgical procedures are recorded according to the French common classification of medical procedures (Classification Commune des Actes M\u0026eacute;dicaux, CCAM). Further details on the French medico-administrative databases have been previously described.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] Given the disruption to healthcare delivery caused by the COVID-19 pandemic and the resulting incompleteness of post-pandemic data, this study was restricted to the period preceding 2020 .\u003c/p\u003e \u003cp\u003eNeither ethics committee approval nor informed consent were required for this observational study based on French medico-administrative databases because of the anonymous nature of the data, by agreement of the French Data Protection Supervisor Authority (Commission Nationale de l\u0026rsquo;Informatique et des Libert\u0026eacute;s - CNIL).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStudy population\u003c/h3\u003e\n\u003cp\u003ePatients who underwent spine surgery in 2018 (codes were described in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e in the Supplement), without spine surgery in the preceding year and aged 18 or older were included. To consider only the degenerative causes, patients with trauma or cancer diagnoses, or those treated with anticancer drugs in the 6 months before spine surgery were excluded. Considering the lack of data for patients not affiliated to the general health insurance regimen, they were excluded.\u003c/p\u003e\n\u003ch3\u003eEvents of interest\u003c/h3\u003e\n\u003cp\u003eIntraoperative and postoperative neurological complications were identified through hospital diagnosis codes and medical procedures in the year after inclusion (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). The corresponding codes were selected by a multidisciplinary committee including neurosurgeon, spine orthopaedic surgeon, epidemiologist and data-scientist.\u003c/p\u003e \u003cp\u003eComplications occurring within the first 30 days following surgery were defined as early.[\u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Only the first occurring complication was classified in the results. Codes corresponding to a common postoperative evolution of the pathology were excluded.\u003c/p\u003e\n\u003ch3\u003ePeriod of interest\u003c/h3\u003e\n\u003cp\u003ePatients were followed for one year from the date of their first spine surgery for degenerative pathology in 2018. Patient follow-up was censored at postoperative day 365 or at the date of death when applicable.\u003c/p\u003e\n\u003ch3\u003eAnalysis\u003c/h3\u003e\n\u003cp\u003eDescriptive statistics characterized the study population by age at inclusion, sex, overweight or obesity status, type of hospital (private or public) where the spine surgery was performed, hospital stay duration, delay between surgery and first complication, and history of previous admissions for degenerative pathologies in the 5 years before inclusion. Medical procedures and diagnoses (at inclusion or as complication) were described using frequency distribution and absolute number.\u003c/p\u003e \u003cp\u003eComplications incidence over time was described using the cumulative incidence curve with the Aalen-Johansen estimator. Multivariable cause-specific Cox regression identified patient characteristics associated with complication during the year following the surgery. The proportional hazard assumption was checked for each covariate tested in the model. All covariates in the model were categorical or categorised.\u003c/p\u003e \u003cp\u003eAnalyses were performed using SAS Enterprise Guide software (version 8.3, SAS Institute, North Carolina, USA) and R (version 4.3.1, R Foundation for Statistical Computing, Vienna, Austria).\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eDescription of patients\u003c/h2\u003e \u003cp\u003eBased on the 63\u0026nbsp;million French people in the database in 2018, 79,151 patients were identified with an incident spine surgery for degenerative pathology (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). About a quarter of patients had an history of hospitalisation for degenerative pathologies before inclusion (29.5%) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Mean patient age at time of surgery was 55 years (SD 15); with 51.0% women and 9.4% overweight or obesity. Procedures at inclusion were mostly related to the lumbar level (80.7%). Average hospitalization duration for surgery was 4.4 days (SD 4.1) and 68.6% occurred in private healthcare institution.\u003c/p\u003e \u003cp\u003e \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\u003eCharacteristics of patients following spine surgery for degenerative spine pathology in 2018, France.\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=\"char\" char=\".\" 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\u003ePopulation (N\u0026thinsp;=\u0026thinsp;79,151)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWomen, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40,381 (51.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e54.9 (15.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpine level of initial surgery, n (%)\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\u003eLumbar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e63,897 (80.7)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e9,028 (11.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLumbar and cervical\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e479 (0.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnspecified\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5,747 (7.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistory of hospitalisation for degenerative pathologies, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23,308 (29.5)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOverweight or obesity, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7,439 (9.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrivate healthcare facility, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e54,332 (68.6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of stay (days), mean (SD)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.4 (4.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"2\"\u003eAbbreviations: SD: Standard Deviation\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eIncidence of complications\u003c/h3\u003e\n\u003cp\u003eThe cumulative incidence of postoperative neurological complications sharply increased to 7.6% within the first 30 days following initial surgery, and kept rising steadily afterwards to reach 14.7% at one-year (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFirst identified complications were more frequently related to lumbar spine than cervical spine or non-defined region: 13.8% of the complications concerned \u0026ldquo;Spinal stenosis, lumbar region\u0026rdquo;, 15.8% \u0026ldquo;Nerve roots and plexuses compressions during intervertebral disc pathology\u0026rdquo;, 3.2% \u0026ldquo;Lumbar or lumbosacral total bilateral laminectomy with arthrectomy, \u003cem\u003evia\u003c/em\u003e posterior approach\u0026rdquo; and 3.1% \u0026ldquo;Debridement of postoperative spinal and/or paravertebral infectious epidural lesion [sepsis], via direct approach\u0026rdquo; (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe description of complications by age group shows little difference apart from the complications of \u0026ldquo;Spinal stenosis, lumbar region\u0026rdquo; and \u0026ldquo;Nerve roots and plexuses compressions during other dorsopathies\u0026rdquo; for which the frequency increased with age, and compression \u0026ldquo;Nerve roots and plexuses compressions during intervertebral disc pathology\u0026rdquo; which decreases with age (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e in the Supplement).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eDeterminants of complications\u003c/h2\u003e \u003cp\u003eMultivariable cause-specific Cox regression showed a significant but non-linear effect of age on the risk of complications (aHR\u0026thinsp;=\u0026thinsp;1.55 95%CI [1.46;1.64] for patients aged\u0026thinsp;\u0026gt;\u0026thinsp;65 vs\u0026thinsp;\u0026le;\u0026thinsp;40) and an association with the initial hospital stay duration (2.73 [2.58;2.89] for stay\u0026thinsp;\u0026gt;\u0026thinsp;5 days vs\u0026thinsp;\u0026le;\u0026thinsp;2 days) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The major determinant of postoperative neurological complications was history of spine degenerative pathology hospitalisation (1.43 [1.38;1.49]). Moreover, overweight or obesity (1.08 [1.02;1.15]), public hospitalization at initial surgery (1.07 [1.03\u0026ndash;1.10]) and female sex (1.05 [1.01;1.08]) were slightly associated with higher complications risks.\u003c/p\u003e \u003cp\u003eTable 2. Risk of complication at one-year post-surgery (cause-specific Cox regression)\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"576\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003eaHR\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e95% CI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003ep\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eSex (female vs male)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e1.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1.01-1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.008\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eAge at initial surgery (vs 40 years and younger)\u003c/p\u003e\n \u003cp\u003e41-50\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e51-65\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026gt;65\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1.13\u003c/p\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003cp\u003e1.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1.06-1.21\u003c/p\u003e\n \u003cp\u003e1.15-1.30\u003c/p\u003e\n \u003cp\u003e1.46-1.64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt;10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eSpine level of initial surgery (vs lumbar)\u003c/p\u003e\n \u003cp\u003eCervical\u003c/p\u003e\n \u003cp\u003eCervical and lumbar\u003c/p\u003e\n \u003cp\u003eCervical and unspecified\u003c/p\u003e\n \u003cp\u003eLumbar and unspecified\u003c/p\u003e\n \u003cp\u003eLumbar and cervical and unspecified\u003c/p\u003e\n \u003cp\u003eUnspecified\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0.98\u003c/p\u003e\n \u003cp\u003e1.38\u003c/p\u003e\n \u003cp\u003e1.39\u003c/p\u003e\n \u003cp\u003e1.00\u003c/p\u003e\n \u003cp\u003e0.88\u003c/p\u003e\n \u003cp\u003e1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0.91-1.05\u003c/p\u003e\n \u003cp\u003e1.13-1.68\u003c/p\u003e\n \u003cp\u003e1.18-1.63\u003c/p\u003e\n \u003cp\u003e0.95-1.06\u003c/p\u003e\n \u003cp\u003e0.28-2.72\u003c/p\u003e\n \u003cp\u003e0.97-1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt;10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eHistory of previous hospitalization for degenerative pathologies (yes vs no)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1.38-1.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026lt;10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eOverweight or obesity (yes vs no)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1.02-1.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e0.009\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eType of healthcare facility (Public vs Private)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e1.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e1.03-1.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 359px;\"\u003e\n \u003cp\u003eLength of stay at initial surgery (vs \u0026le; 2 days)\u003c/p\u003e\n \u003cp\u003e3 days\u003c/p\u003e\n \u003cp\u003e4-5 days\u003c/p\u003e\n \u003cp\u003e\u0026gt;5 days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 56px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e1.01\u003c/p\u003e\n \u003cp\u003e1.20\u003c/p\u003e\n \u003cp\u003e2.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e0.94-1.08\u003c/p\u003e\n \u003cp\u003e1.13-1.27\u003c/p\u003e\n \u003cp\u003e2.58-2.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e\u0026lt;10\u003csup\u003e-3\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: aHR: adjusted Hazard Ratio; 95%CI: 95% Confidence Interval\u003c/p\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis nationwide French cohort including more than 79,000 patients undergoing surgery for degenerative spine disorders showed that nearly one in six experienced a neurological complication within the year following surgery. The risk of complications was higher among older patients, women, individuals with overweight or obesity, those with a history of hospitalization for degenerative spinal disease, in cases involving cervical or multilevel procedures, in those with prolonged initial hospital stay, and in patients treated in public institutions. These findings highlight the multifactorial nature of postoperative neurological risk and provide the first national overview of neurological complications following surgery for degenerative spinal disorders in France.\u003c/p\u003e \u003cp\u003eWhen compared with the international literature, our findings are broadly consistent, although substantial variability exists across regions, study designs, and outcomes definitions. In the United States, analyses of large administrative datasets have reported 30-day neurological complication rates of approximatively 5%, which are substantially lower than the one-year cumulative incidence observed in our study.(16) A multicentre study conducted in Washington state (USA) including 24,882 patients who underwent lumbar surgery for degenerative spine disorders between 1990 and 1993 reported a cumulative reoperation incidence of 19% at 11 years of follow-up.(20) Similarly, a multicentre study from the Province of Ontario (Canada) including 4,722 patients undergoing first-time spinal surgery between 1900 and 1991 reported a reoperations rate of 9.5%, with a maximum follow-up of 4 years.(21)\u003c/p\u003e \u003cp\u003eMulticenter studies from Latin America and North America focusing on spinal and cervical deformities have reported complication rates ranging from 9% to 19%, depending on follow-up duration and procedural complexity.(17,18) In Europe, a nationwide Norwegian study used the Global Perceived Effect scale to measure the patients\u0026rsquo; perception of their own health after surgery for degenerative myelopathy at 1 year. It revealed a 16% rate of patients measuring their health as slightly worse, much worse or worse than ever.(19) European registry data reported perioperative complication rates between 10% and 17%(22), which are comparable to those observed in the present study.\u003c/p\u003e \u003cp\u003eThese discrepancies underscore the influence of population characteristics, surgical indications, follow-up duration, and outcome definitions. Nonetheless, they consistently indicate that neurological complications remain frequent and clinically meaningful across different healthcare systems.\u003c/p\u003e \u003cp\u003eSeveral factors may explain the determinants identified in our analysis. The slightly higher risk observed among women may be related to skeletal fragility, particularly postmenopausal osteoporosis, which increases vulnerability to surgical stress on the spine. However, this interpretation remains speculative and should be regarded as a hypothesis for future research rather than a firm conclusion. Age also emerged as a strong predictor, consistent with the accumulation of comorbidities, frailty, and reduced physiological reserve in older patients.\u003c/p\u003e \u003cp\u003eThe association with overweight or obesity is biologically plausible, as excess body mass increases mechanical loading on the spine, complicates surgical exposure, and may predispose to impaired wound healing. Multilevel procedures, by prolonging operative time and tissue exposure, logically entail a higher risk of neurological injury.\u003c/p\u003e \u003cp\u003eA prolonged initial hospital stay is more likely to reflect perioperative complications or poorer baseline health status, and could be interpreted as a marker of increased risk rather than a direct causal factor.\u003c/p\u003e \u003cp\u003eFinally, the slightly higher complication rates observed in public hospitals may be linked to patient selection, with more complex or severe cases preferentially referred to these institutions, or to organizational and structural variations in care delivery.\u003c/p\u003e \u003cp\u003eThis study has several limitations that should be acknowledged. The use of the SNDS database precludes access to detailed clinical information such as preoperative neurological status, imaging findings, smoking history, or bone mineral density, nor to lifestyle or socioeconomic factors that may influence postoperative outcomes. Moreover, the one-year follow-up may underestimate the incidence of late neurological complications, particularly those related to pseudarthrosis, which can lead to delayed to nerve root compression.[\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] The retrospective design limits causal inference, and coding inaccuracies are possible despite careful validation by experienced spine surgeons.\u003c/p\u003e \u003cp\u003eNevertheless, the large sample size, nationwide coverage, and standardized coding of diagnoses and procedures provide robust population-based estimates and support the generalizability of our findings to the French population.\u003c/p\u003e \u003cp\u003eFrom a clinical perspective, these findings underscore the importance of preoperative identification of patient subgroups at increased risk of neurological complications following spine surgery. Particular attention should be paid to older and female patients, individuals with overweight or obesity, and those requiring multilevel procedures, as targeted perioperative optimization may help mitigate risk. Enhanced monitoring and tailored rehabilitation strategies in these populations could contribute to reducing complication rates and improving long-term outcomes. At a broader level, the findings underline the value of nationwide health databases in guiding public health decisions and supporting the development of evidence-based clinical practice guidelines in spine surgery.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eNeurological complications within the year following spine surgery in patients with degenerative spinal disorders occur in approximately one out of six patients. This risk is influenced by preoperative and perioperative characteristics, including, sex, age, length of the initial hospital stays, body mass index, spinal level and extent of the index procedure, type of healthcare facility, and prior hospitalization for degenerative spinal disease. These determinants are relevant when considering surgical management and planning postoperative follow-up in patients undergoing spine surgery for degenerative pathology.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eData sharing statement\u003c/h2\u003e \u003cp\u003eNo additional data available by author (French law to access SNDS \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ewww.health-data-hub.fr\u003c/a\u003e\u003c/span\u003e\u003cspan address=\"http://www.health-data-hub.fr\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e).\u003c/p\u003e \u003ch2\u003eConflict of interest disclosures\u003c/h2\u003e \u003cp\u003eCo-authors have no conflict of interest.\u003c/p\u003e\u003ch2\u003eEthic approval\u003c/h2\u003e \u003cp\u003eBy agreement of the French Data Protection Supervisory Authority (CNIL), neither ethics committee approval nor informed consent were required for this observational study based on anonymized French medico administrative databases.\u003c/p\u003e \u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eGrant of the SFCR (French Society of spine surgery).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eR.G. and J.B. conducted the statistical analyses and wrote the main manuscript text and E.F. prepared figures 1-3. All authors reviewed the manuscript\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors would like to thank the French Society of Spinal Surgery for funding this Biostatistics internship, and Prof. Antoine Pariente for his critical review of the manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe French database (Syst\u0026egrave;me National des Donn\u0026eacute;es de Sant\u0026eacute;) that support the findings of this study are available from www.health-data-hub.fr, but restrictions apply to the availability of these data, and so are not publicly available. The data are, however, available upon request and with the permission of the French Ministry of Health.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRavindra VM, Senglaub SS, Rattani A et al (2018) Degenerative Lumbar Spine Disease: Estimating Global Incidence and Worldwide Volume. 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Eur Spine J Off Publ Eur Spine Soc Eur Spinal Deform Soc Eur Sect Cerv Spine Res Soc 12:178\u0026ndash;189. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00586-002-0493-8\u003c/span\u003e\u003cspan address=\"10.1007/s00586-002-0493-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKitzen J, Vercoulen TFG, van Kuijk SMJ et al (2020) Long-term clinical outcome of two revision strategies for failed total disc replacements. 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Eur Spine J Off Publ Eur Spine Soc Eur Spinal Deform Soc Eur Sect Cerv Spine Res Soc 27:1972\u0026ndash;1980. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00586-018-5508-1\u003c/span\u003e\u003cspan address=\"10.1007/s00586-018-5508-1\" 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":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"spine surgery, degenerative pathology, neurological complications","lastPublishedDoi":"10.21203/rs.3.rs-8418831/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8418831/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose –\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn France, around 160,000 spine surgery procedures are performed yearly for spinal deformities or degenerative, tumoral, or traumatic spine pathologies. This study aimed to describe neurological complications following spine surgery for degenerative pathology and identify their determinants at the national level.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods –\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUsing the French national health insurance system database (Système National des Données de Santé, SNDS), a cohort was constituted including all French patients aged 18 and older in 2018 who underwent their first surgery for degenerative spine pathology in that year. Complications were identified through hospital diagnoses and surgical procedures within the following 12 months. Patient characteristics and complications were described. A cause-specific Cox model was used to identify the determinants of spine surgery complications.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults –\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 79,151 patients were identified with incident spine surgery for degenerative pathology (mean patient age 55 years, standard deviation 15; 51.0% women) and 14.8% of them had one or more complications within one year after surgery. Determinants associated with the occurrence of complications were female sex (HR = 1.05, 95%CI=[1.01;1.09]), age \u0026gt; 65 (1.55 [1.46;1.64]), length of stay for initial surgery \u0026gt; 5 days (2.73 [2.58;2.89]), lumbar and cervical spine levels (1.38 [1.13;1.68]), overweight or obesity (1.08 [1.02;1.15]), public institution (1.07 [1.03;1.12]) and previous consultation for the pathology (1.43 [1.38;1.49]).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion –\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAlmost one in six patients with degenerative spine pathology develops a complication after surgery. Main determinants of postoperative complications appear to be associated with disease severity and comorbidities.\u003c/p\u003e","manuscriptTitle":"Determinants of Neurological Complications after Degenerative Spine Surgery: a Nationwide Cohort Study based on the French SNDS Database","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-12 05:36:22","doi":"10.21203/rs.3.rs-8418831/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-01T16:38:20+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-28T11:42:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"326471703797053841790479079136537038355","date":"2026-01-13T17:04:59+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-12T16:08:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"83480402039246125398425835365076232036","date":"2026-01-06T20:36:59+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-06T18:41:11+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-23T08:37:41+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-23T08:36:49+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Spine Journal","date":"2025-12-21T17:33:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-spine-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"esjo","sideBox":"Learn more about [European Spine Journal](http://link.springer.com/journal/586)","snPcode":"586","submissionUrl":"https://submission.springernature.com/new-submission/586/3","title":"European Spine Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"34a7c696-eb3f-4401-b00d-120afb43ba4d","owner":[],"postedDate":"January 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-11T14:53:08+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-12 05:36:22","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8418831","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8418831","identity":"rs-8418831","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}