Distinct Recurrence Patterns and Risk Factors Following Nonoperative Management of Acute Appendicitis versus Appendiceal Abscess in Children: Implications for Risk Stratification

Distinct Recurrence Patterns and Risk Factors Following Nonoperative Management of Acute Appendicitis versus Appendiceal Abscess in Children: Implications for Risk Stratification | 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 Distinct Recurrence Patterns and Risk Factors Following Nonoperative Management of Acute Appendicitis versus Appendiceal Abscess in Children: Implications for Risk Stratification Zhendi Tang, Pengcheng Luo, Jiajia Zhou, Quan Kang, Dengliang Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9188553/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 9 You are reading this latest preprint version Abstract Objective To compare recurrence patterns and identify risk factors after nonoperative management of acute appendicitis (AA) and periappendiceal abscess (PAA) in children. Methods In this retrospective cohort study, children (< 18 years) with AA or PAA (defined by imaging) and treated nonoperatively (Jan 2020–Jul 2024) were included. The primary outcome was clinical recurrence. Risk factors were identified using multivariable logistic regression and Kaplan–Meier analysis. Results Among 409 patients (median follow-up 38.8 months), recurrence was higher in the PAA group than in the AA group (26.5% vs. 14.9%), with earlier recurrence (HR 2.09, 95% CI 1.34–3.26; p < 0.001). In the PAA group, the presence of an appendicolith (adjusted odds ratio [aOR] 2.98, 95% CI 1.19–7.84) and a higher abscess-to-weight ratio at admission (aOR 1.12 per unit, 95% CI 1.01–1.26) were independent risk factors for recurrence, whereas a longer length of hospital stay was protective (aOR 0.89 per day, 95% CI 0.80–0.97). In the AA group, a negative pretreatment ultrasound finding was protective (OR 0.21, 95% CI 0.04–0.97). Surgical pathology of recurrent cases showed a predominance of gangrenous appendicitis in the PAA group versus suppurative appendicitis in the AA group (p = 0.032). Conclusion Following nonoperative management, PAA is associated with a high risk of early recurrence, driven by appendicolith and greater infectious burden, which justifies enhanced early surveillance and consideration of interval appendectomy. Recurrence risk in AA is lower and more protracted, particularly when ultrasound is negative. These findings support a risk-stratified approach to management. Acute appendicitis Periappendiceal abscess Conservative treatment Recurrence Risk factors Children Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Acute appendicitis represents the most prevalent surgical emergency in the pediatric population, typically managed by prompt appendectomy to prevent perforation and its associated morbidity [ 1 ]. Laparoscopic appendectomy is thus considered the gold standard for uncomplicated cases [ 2 – 4 ]. However, this surgical paradigm is increasingly scrutinized. Pediatric surgery carries inherent risks, including anesthesia complications, postoperative intra-abdominal abscesses, and adhesion formation, which can be particularly consequential in young children [ 5 , 6 ]. Consequently, non-operative management (NOM) with antibiotics has emerged as a viable alternative for uncomplicated acute appendicitis (AA) [ 7 – 10 ], with studies in both adults and children demonstrating comparable efficacy to surgery [ 11 , 12 ]. A more complex scenario arises in periappendiceal abscess (PAA), which complicates 2%–10% of appendicitis cases [ 13 ]. Initial NOM—often involving antibiotics with or without percutaneous drainage—is standard, typically followed by an elective interval appendectomy [ 14 ]. A critical, unresolved challenge common to both AA and PAA managed non-operatively is the risk of disease recurrence [ 15 ]. Crucially, robust evidence to guide the necessity of interval appendectomy after successful NOM remains lacking, leading to ongoing clinical controversy [ 16 , 17 ]. Therefore, to enable a risk-stratified clinical approach, this study aimed to directly compare long-term recurrence patterns and identify distinct predictors of recurrence following NOM in pediatric patients with AA versus those with PAA. Methods Study design and participants We conducted a retrospective cohort study of pediatric patients (aged < 18 years) diagnosed with AA or PAA and initially managed non-operatively at the Children's Hospital of Chongqing Medical University between January 2020 and July 2024. Inclusion criteria were: (1) a clinical diagnosis of AA or PAA confirmed by ultrasound (US) findings (e.g., a dilated, non-compressible appendix ≥ 7 mm in diameter, presence of periappendiceal fluid collection, or an appendicolith) and supported by clinical signs (right lower quadrant tenderness) and laboratory inflammation (leukocyte count > 10 × 10⁹/L); (2) selection of NOM after informed consent from guardians; (3) clinical improvement with antibiotic therapy leading to discharge without emergency surgery. Exclusion criteria were: (1) incomplete clinical or follow-up data, or (2) pre-existing malignant disease. Data collection and variables Data were extracted from electronic medical records and included demographics (age, sex, weight), clinical presentation (symptom duration), admission diagnosis, and hospital course (length of stay). US findings (appendiceal diameter, presence of appendicolith or abscess) were recorded at admission and discharge. For the PAA subgroup, abscess volume (calculated using the ellipsoid formula: π/6 × length × width × depth) and the abscess-to-weight ratio were determined. The primary outcome was disease recurrence, defined as a subsequent hospitalization for clinically and radiologically confirmed appendicitis requiring intervention (surgery or drainage) after initial successful NOM. For recurrent cases undergoing surgery, pathological reports were reviewed. Statistical analysis Analyses were performed using R (v.4.5.2). Continuous data are presented as median (interquartile range, IQR) or mean (95% confidence interval, CI) based on distribution, assessed via the Shapiro–Wilk test and quantile-quantile plots. Categorical data are presented as frequencies (percentages). Group comparisons (AA vs. PAA) for the primary outcome used Kaplan–Meier survival analysis with the log-rank test, reported as hazard ratio (HR) with 95% CI. To identify independent predictors of recurrence, univariate logistic regression was first performed for all clinically relevant variables within the AA and PAA subgroups separately. Variables with P < 0.10 in univariate analysis were entered into a backward stepwise multivariate logistic regression model, with results expressed as adjusted odds ratios (aORs) with 95% CIs. A two-sided P < 0.05 was considered statistically significant. Missing data were handled by multiple imputation with chained equations (MICE, m = 5). Ethical approval The study protocol was approved by the Ethics Review Committee of the Children's Hospital of Chongqing Medical University (Approval No.: 2026-LinYan 18). The requirement for individual informed consent was waived due to the retrospective design. Results Study selection Between January 2020 and July 2024, 415 pediatric patients were initially identified as having received non-operative management for appendicitis. After applying exclusion criteria, six patients were removed: five due to loss to follow-up and one due to a coexisting malignant disease. Thus, the final analytic cohort comprised 409 patients, with a median follow-up of 38.8 months. Of these, 262 (64.1%) were diagnosed with AA and 147 (35.9%) with PAA. All diagnoses were clinically and radiologically confirmed. The study flow is detailed in Figure 1 . Baseline characteristics The baseline demographic and clinical characteristics of the entire cohort (n=409) and the AA and PAA subgroups are summarized in Table 1 . Overall, the median age was 9 years (IQR, 8–10), median weight was 30.0 kg (IQR, 26.0–34.0), 242 patients (59.2%) were male, and the median hospital stay was 6 days (IQR, 5–7). Follow-up and recurrence The median follow-up time for the cohort was 38.8 months (IQR, 27.3–54.5), estimated by the reverse Kaplan–Meier method. Over this period, 78 of 409 patients (19.1%) experienced disease recurrence. The median time to recurrence was 137.5 days (IQR, 32.0–321.8). Recurrence-free survival differed significantly between the AA and PAA groups (log-rank P < 0.001). Patients with PAA had a more than twofold higher risk of recurrence, with earlier onset (hazard ratio [HR] for PAA vs. AA, 2.09; 95% CI, 1.34–3.26). The Kaplan–Meier curves ( Figure 2 ) illustrate this disparity: survival rates at 3, 6, and 12 months were 94.9%, 87.7%, and 84.6%, respectively, for the entire cohort, with a steeper initial decline in the PAA group. The curves plateaued after the first year. The number of patients at risk at each time point is provided beneath the figure. Subgroup-specific recurrence patterns and pathology In the AA subgroup (n = 262), 39 patients (14.9%) recurred. Of these, 22 (56.4%) underwent interval appendectomy, while 17 continued NOM. One patient in the latter group had a second recurrence and proceeded to surgery; pathology indicated suppurative appendicitis. In the PAA subgroup (n = 147), 39 patients (26.5%) recurred, and 23 (59.0%) underwent surgery. Three patients managed conservatively after the first recurrence experienced a second recurrence, all of whom subsequently underwent appendectomy. Pathological findings in these surgical cases were predominantly gangrenous appendicitis (2 of 3, 66.7%; the third showed chronic inflammation). Comparison between AA and PAA groups In the comparison between AA and PAA groups, univariate analysis identified several differentiating factors ( Table 1 ). Multivariate logistic regression confirmed that a shorter length of stay, longer duration of pain, and the presence of an appendicolith were independently associated with PAA (all P < 0.05). The discriminative ability of this model for distinguishing AA from PAA was moderate (area under the receiver operating characteristic curve [AUC] = 0.640; Figure 3A ). Key factors are visualized in a forest plot ( Figure 4A ). Predictors within the AA subgroup Within the AA subgroup (n = 262), univariate analysis identified appendiceal diameter and a negative pretreatment ultrasound as potential predictors of recurrence. In the adjusted multivariate model, a negative pretreatment ultrasound finding remained a significant independent protective factor (aOR = 0.21; 95% CI, 0.04–0.97; P = 0.045) ( Table 2 ). The model demonstrated fair predictive accuracy for recurrence (AUC = 0.707; Figure 3B ). The corresponding forest plot is shown in Figure 4B . Predictors within the PAA subgroup Within the PAA subgroup (n = 147), age, weight, and a higher abscess-to-weight ratio at admission were associated with recurrence in univariate analysis. The final multivariate model identified three independent predictors: 1) the presence of an appendicolith (aOR = 2.98; 95% CI, 1.19–7.84), 2) a higher abscess-to-weight ratio at admission (aOR = 1.12 per unit increase; 95% CI, 1.01–1.26), and 3) a longer hospital stay, which was protective (aOR = 0.89 per day; 95% CI, 0.80–0.97) (all P < 0.05) ( Table 3 ). This model showed good discriminative ability (AUC = 0.782; Figure 3C ), as further detailed in the forest plot ( Figure 4C ). Discussion This retrospective study of pediatric patients with acute appendicitis, including both uncomplicated and complicated forms, found an overall recurrence rate of 19.1% after non-operative management, a figure consistent with previous reports [18]. The recurrence rates observed in the acute appendicitis (14.9%) and periappendiceal abscess (26.5%) subgroups were also comparable to those documented in prior literature [7, 19]. The present analysis contributes a sizable cohort of children with imaging-confirmed diagnoses and offers a median follow-up duration that surpasses that of many previous studies. Comparative analysis revealed that patients with PAA had a significantly longer duration of pain and a higher prevalence of appendicolith than those with AA. These factors are well-established markers of disease severity and progression. The association between prolonged symptom duration and perforation or abscess formation is consistently reported [20]. Similarly, an appendicolith acts as a nidus for obstruction and localized ischemia, substantially increasing the risk of complicated appendicitis [21, 22]. The observed longer hospital stay in the PAA group logically reflects the more intensive antibiotic regimens required for abscess management, rather than being an independent risk factor per se. A key finding of our study is that, despite a higher observed recurrence rate in the PAA group, multivariate analysis did not identify PAA as an independent predictor of recurrence compared to AA. We propose two non-mutually exclusive explanations for this apparent paradox. First, the distinct pathophysiology of PAA may confer a degree of protection after initial healing. Following perforation, localized encapsulation by the omentum and adjacent bowel, accompanied by fibroblast activation and collagen deposition, leads to appendiceal fibrosis [23, 24]. This resultant fibrotic scar tissue forms a dense, avascular barrier that is less permeable to bacterial translocation and provides a suboptimal environment for acute inflammatory exacerbation after antibiotic therapy, potentially mitigating reinfection risk. Second, our institutional protocol recommending elective interval appendectomy ~3 months after successful NOM for PAA introduces a competing risk. This planned surgical intervention truncates the natural follow-up period for a subset of PAA patients, potentially censoring future recurrence events and thus attenuating the measured recurrence rate in this subgroup. Regarding predictors within the AA subgroup, a negative pretreatment ultrasound finding emerged as a strong independent protective factor (aOR = 0.21; 95% CI, 0.04–0.97), associated with a markedly lower recurrence rate (6.3% vs. 19.8%). This may point to divergent mechanisms of recurrence between AA and PAA. For AA, recurrence likely constitutes a de novo inflammatory episode. Initial antibiotic therapy suppresses the acute infection but does not eliminate the underlying predisposition to luminal obstruction or dysregulated immune response within the appendix [25, 26]. Subsequent recurrence may thus represent a reactivation of this latent pathophysiology. In contrast, “recurrence” in PAA may be more accurately characterized as a persistence or recrudescence of the original infectious nidus. The pathological substrate is not a newly inflamed organ, but residual necrotic tissue, an appendicolith, or a contained micro-abscess. Clinical reappearance of symptoms may occur when host immune surveillance wanes or local containment fails [27]. Within the PAA subgroup, our analysis identified three independent factors predictive of recurrence. First, the presence of an appendicolith was confirmed as a strong, independent risk factor (aOR = 2.98; 95% CI, 1.19-7.84), consistent with prior evidence [28, 29]. This finding elevates the appendicolith from a diagnostic feature to a key prognostic marker for NOM failure. Its role extends beyond initial luminal obstruction; as a persistent foreign body, it can impair abscess drainage, sustain a bacterial nidus, and hinder antibiotic efficacy, thereby complicating definitive non-operative cure. Second, we introduced the novel metric Abscess_to_weight_ratio_on_admission, which was independently associated with increased recurrence risk (aOR = 1.12 per unit increase). This ratio integrates the infectious burden (abscess volume) with a proxy for host resilience (body weight), providing a more holistic measure of disease severity than anatomical size alone. Its clinical relevance is intuitive: a larger abscess in a smaller child signifies a greater pathophysiological imbalance. Further prospective studies are warranted to validate its predictive utility and define optimal thresholds. Conversely, a longer hospital stay was protective (aOR = 0.89 per day). This underscores the principle that adequate initial therapy is paramount [30]. For PAA, an extended inpatient phase likely ensures complete intravenous antibiotic course, proper transition to oral therapy, and confirmation of clinical stability, thereby reducing the risk of premature treatment cessation and subsequent relapse. Kaplan–Meier survival analysis revealed a distinct temporal pattern of recurrence between the two groups. Recurrence occurred significantly earlier in the PAA group (log-rank P < 0.001), with nearly half of the events observed within the first month after treatment. In contrast, recurrences in the AA group were distributed more evenly over a prolonged period, from 3 months to 3 years. This pattern strongly suggests that early “recurrence” in PAA is closely linked to incomplete control of the initial infectious focus, whereas later recurrence in AA may represent a distinct pathophysiology. These findings have direct clinical implications. For patients with AA managed non-operatively, it is essential to emphasize the persistent, long-term risk of recurrence, which our data associate with a positive pretreatment ultrasound finding [31]. For patients with PAA, the first post-discharge month constitutes a critical high-risk window that warrants close clinical surveillance. The presence of an appendicolith—a strong risk indicator in our cohort—should prompt serious consideration of elective interval appendectomy after initial infection control [18, 32]. Pathological examination of surgical specimens provided further mechanistic insight. Appendectomy after recurrence revealed a predominance of suppurative appendicitis in the AA group, contrasting with gangrenous appendicitis in the PAA group (P = 0.032). This histopathological divergence reinforces the proposed distinction in recurrence mechanisms. The suppurative pattern in AA is consistent with a de novo inflammatory event, potentially driven by persistent anatomical or functional predispositions (e.g., luminal narrowing). Conversely, the necrotic, gangrenous pathology in PAA aligns with the concept of incomplete eradication or recrudescence of the initial severe infection, an interpretation supported by the early recurrence pattern observed in this group. An interesting trend was observed in the AA subgroup: a larger appendiceal diameter at discharge was associated with a substantially increased recurrence risk, though this did not reach conventional statistical significance (OR = 3.76; 95% CI, 0.91–17.8; P = 0.068) [33]. The large point estimate (OR = 3.76) suggests a clinically meaningful effect, while the wide CI, spanning from near-null to very high risk, primarily reflects the limited sample size for this specific analysis. This result does not negate a potential association but underscores the need for future studies with larger cohorts to obtain a more precise estimate. Pathophysiologically, a persistently dilated appendix at discharge may signify incomplete resolution of inflammation or subclinical obstruction. Even after clinical and laboratory parameters normalize, residual wall edema, retained secretions, or micro-appendicoliths could sustain luminal patency, creating an anatomical predisposition for the reactivation of acute inflammation. Several limitations of this study warrant consideration. First, its retrospective, single-center design is susceptible to selection bias and unmeasured confounding. Although we adjusted for known covariates, residual confounding from factors such as microbial profiles or outpatient antibiotic adherence cannot be ruled out. Second, despite efforts to contact patients, loss to follow-up and reliance on outside-hospital records may have led to incomplete outcome ascertainment. Third, the sample size, particularly within certain risk-stratified subgroups (e.g., those with an appendicolith), limited the statistical power and precision of some estimates, as reflected in wide confidence intervals; these findings require validation in larger cohorts. Finally, clinical management—including antibiotic choice, duration, and the use/timing of drainage—was guided by institutional pathways rather than a uniform protocol. While this reflects real-world practice, it may affect the generalizability of results to centers with differing treatment strategies. Conclusion In conclusion, this study delineates distinct recurrence patterns and risk profiles following NOM of pediatric AA and PAA. Our findings demonstrate that recurrence in PAA is an early event, concentrated within the first month and indicative of initial infection control failure, driven by factors such as the presence of an appendicolith and a higher abscess-to-weight ratio. In contrast, recurrence in AA follows a protracted, long-term course, aligning with de novo inflammatory episodes and associated with a positive pretreatment ultrasound finding. These insights support a risk-stratified management paradigm. For PAA, particularly in cases with an appendicolith, management should prioritize intensified early surveillance and strong consideration of elective interval appendectomy. For AA, especially when ultrasound is negative, standard NOM with long-term follow-up is appropriate, with care plans guided by shared decision-making. This study affirms the feasibility of NOM in children while highlighting the need for tailored strategies based on disease phenotype. Future prospective studies are needed to validate these predictors and to integrate them into robust clinical prediction models. Declarations Funding: None. Conflicts of interest: The authors declare that there are no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Ethics approval: This study, which involved the analysis of retrospective patient medical record data, was approved by the Ethics Committee of the Children’s Hospital of Chongqing Medical University (Approval No.: 2026-LinYan 18). The requirement for informed consent was waived by the same ethics committee due to the retrospective nature of the study. All procedures were performed in accordance with the ethical standards of the Declaration of Helsinki. Consent to participate: Not applicable. This study did not involve direct human participants. Author Contribution： Zhendi Tang: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Data Curation, Writing – Original Draft, Visualization. Pengcheng Luo: Methodology, Software, Validation, Investigation, Writing – Review & Editing. Jiajia Zhou: Resources, Data Curation, Writing – Review & Editing, Supervision. Quan Kang: Formal analysis, Writing – Review & Editing, Project administration. Dengliang Wang (Corresponding Author): Conceptualization, Resources, Writing – Review & Editing, Supervision, Project administration, Funding acquisition. All authors have read and approved the final manuscript. Data Availability declaration: All data generated or analyzed during this study are included in the Supplementary Material of this article. References Stöß C, et al. Acute Appendicitis: Trends in Surgical Treatment—A Population-Based Study of Over 800 000 Patients. Dtsch Arztebl Int. 2021;118(14):244–9. Kumar SS, et al. SAGES guideline for the diagnosis and treatment of appendicitis. Surg Endosc. 2024;38(6):2974–94. Bachur RG, Lipsett SC, Monuteaux MC. Outcomes Nonoperative Manage Uncomplicated Appendicitis Pediatr, 2017. 140(1). Brucchi F, et al. A meta-analysis and trial sequential analysis comparing nonoperative versus operative management for uncomplicated appendicitis: a focus on randomized controlled trials. World J Emerg Surg. 2024;19(1):2. 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J Gastrointest Surg. 2013;17(4):766–70. Park HC, Kim MJ, Lee BH. The outcome of antibiotic therapy for uncomplicated appendicitis with diameters ≤ 10 mm. Int J Surg. 2014;12(9):897–900. Tables Table 1 Univariate and multivariate analyses of clinical characteristics in AA and PAA. AA, acute appendicitis; PAA, periappendiceal abscess. Variables Acute appendicitis N = 262 1 Periappendiceal abscess N = 147 1 Univariable Multivariable p-value 2 OR (95% CI) 3 p-value Gender 0.060 0.300 Male 164 (63%) 78 (53%) 0.59(0.23–1.49) Female 98 (37%) 69 (47%) 1.00(Reference) Age 8.98 ± 3.06 6.88 ± 3.34 < 0.001 0.85(0.66–1.08) 0.200 Weight 32.92 ± 13.73 26.42 ± 13.84 < 0.001 0.99(0.94–1.06) 0.900 Length_of_stay 4.05 ± 1.80 12.22 ± 5.27 < 0.001 1.96(1.64–2.44) < 0.001 Duration_of_pain 1.79 ± 2.77 7.14 ± 3.41 < 0.001 1.36(1.21–1.57) < 0.001 Appendicolith 7 (2.7%) 49 (34%) < 0.001 5.30(1.17–27.7) 0.030 Recurrence 39 (15%) 39 (27%) 0.004 1.71(0.60–4.77) 0.300 Histopathology 0.032 Simple appendicitis 1 (4.5%) 2 (8.7%) Suppurative appendicitis 14 (64%) 6 (26%) Gangrenous appendicitis 7 (32%) 15 (65%) 1 n (%); Mean ± SD 2 Pearson's Chi-squared test; Wilcoxon rank sum test; Fisher's exact test 3 Abbreviations: CI = Confidence Interval, OR = Odds Ratio Table 2 Univariate and multivariate analyses of children with AA: recurrence versus non-recurrence. AA, acute appendicitis. Variables Non-recurrence N = 223 1 Recurrence N = 39 1 Univariable Multivariable p-value 2 OR (95% CI) 3 p-value 2 Gender 0.198 0.300 Male 136 (61%) 28 (72%) 1.54(0.70–3.54) Female 87 (39%) 11 (28%) 1.00(Reference) Age 8.96 ± 3.05 9.12 ± 3.13 0.623 1.09(0.88–1.35) 0.400 Weight 32.94 ± 13.90 32.81 ± 12.85 0.833 0.98(0.93–1.03) 0.500 Length_of_stay 3.96 ± 1.69 4.56 ± 2.29 0.126 1.12(0.93–1.36) 0.200 Duration_of_pain 1.75 ± 2.83 2.06 ± 2.42 0.583 Appendicolith 6 (2.7%) 1 (2.6%) > 0.999 Appendiceal_diameter_on_admission 0.46 ± 0.38 0.62 ± 0.33 0.005 0.31(0.04–2.15) 0.200 Appendiceal_diameter_at_discharge 0.23 ± 0.30 0.41 ± 0.33 < 0.001 3.76(0.91–17.8) 0.068 Ultrasound_negative 89 (40%) 6 (15%) 0.003 0.21(0.04–0.97) 0.045 1 n (%); Mean ± SD 2 Wilcoxon rank sum test; Pearson's Chi-squared test; Fisher's exact test 3 Abbreviations: CI = Confidence Interval, OR = Odds Ratio Table 3 Univariate and multivariate analyses of children with PAA: recurrence versus non-recurrence. PAA, periappendiceal abscess. Variables Non-recurrence N = 108 1 Recurrence N = 39 1 Univariable Multivariable p-value 2 OR (95% CI) 3 p-value 2 Gender 0.388 0.400 Male 55 (51%) 23 (59%) 1.42(0.60–3.46) Female 53 (49%) 16 (41%) 1.00(Reference) Age 7.26 ± 3.38 5.82 ± 3.01 0.010 1.14(0.84–1.63) 0.400 Weight 28.39 ± 14.67 20.95 ± 9.39 0.003 0.92(0.82-1.00) 0.110 Length_of_stay 12.61 ± 5.35 11.13 ± 4.96 0.132 0.89(0.80–0.97) 0.014 Duration_of_pain 7.19 ± 3.11 7.01 ± 4.17 0.693 Appendicolith 32 (30%) 17 (45%) 0.090 2.98(1.19–7.84) 0.022 Condition_at_discharge 72 (68%) 21 (55%) 0.161 Abscess_to_weight_ratio_on_admission 3.70 ± 3.16 5.84 ± 5.02 0.003 1.12(1.01–1.26) 0.039 Abscess_to_weight_ratio_at_discharge 0.62 ± 0.97 0.74 ± 1.79 0.293 Discharge_to_admission_ abscess_ratio 0.28 ± 0.59 0.14 ± 0.27 0.095 0.35(0.06–1.35) 0.200 1 n (%); Mean ± SD 2 Wilcoxon rank sum test; Pearson's Chi-squared test 3 Abbreviations: CI = Confidence Interval, OR = Odds Ratio Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 13 May, 2026 Reviewers agreed at journal 07 May, 2026 Reviewers agreed at journal 06 May, 2026 Reviewers agreed at journal 28 Mar, 2026 Reviewers invited by journal 25 Mar, 2026 Editor invited by journal 24 Mar, 2026 Editor assigned by journal 24 Mar, 2026 Submission checks completed at journal 24 Mar, 2026 First submitted to journal 21 Mar, 2026 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. We do this by developing innovative software and high quality services for the global research community. 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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-9188553","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":612083810,"identity":"1beebff0-1afe-429d-afbb-520d4dbc1a37","order_by":0,"name":"Zhendi Tang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Zhendi","middleName":"","lastName":"Tang","suffix":""},{"id":612083811,"identity":"d91a9556-cb9f-41f9-8656-7d3ed79ee44e","order_by":1,"name":"Pengcheng Luo","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Pengcheng","middleName":"","lastName":"Luo","suffix":""},{"id":612083812,"identity":"2d8e0ad0-f8cc-446c-ad6c-4a844b6e159a","order_by":2,"name":"Jiajia Zhou","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Jiajia","middleName":"","lastName":"Zhou","suffix":""},{"id":612083813,"identity":"3d1e4205-1b75-401c-a1c3-163dc0a9a1ab","order_by":3,"name":"Quan Kang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Quan","middleName":"","lastName":"Kang","suffix":""},{"id":612083814,"identity":"c9a4909a-83a4-469c-8111-cf23842a91e2","order_by":4,"name":"Dengliang Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYFCC5PbPPwxq6vn5mw8/+GBgY0eElsQ2ZoaKYwmSM46lGc4oSEsmUssZ5gSDAzkG0jwfDjE2ENJgcDyx7XFhG1sew4EzBsY2BgeYGdgPH92AV8uZh+3GM9tkihmb2woe5xjc4WPgSUu7gU+L2Y3EBgneNjbGZobDG4xzDJ4xM0jwmBGjhZmxjSHBQNrC4DBjAxFa2qR5zjAn9jCkGEgzEKPF/szDZsMZFceMJSSAgdxjkJbMRsgvku3JB4ExWCNnfx4YlT/+2Njxsx8+hlcLJmAjTfkoGAWjYBSMAmwAAE0BUu9Z+QBjAAAAAElFTkSuQmCC","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Dengliang","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2026-03-22 01:53:42","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9188553/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9188553/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105571340,"identity":"43186e3e-e789-4a34-9fd9-f4c4a8f52310","added_by":"auto","created_at":"2026-03-27 13:22:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":177055,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFlow chart of the study design.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9188553/v1/31fe552c1d0f46f90aafd4a1.png"},{"id":105571918,"identity":"e3ba997f-6d6d-45a4-af8d-5bc90ad46c89","added_by":"auto","created_at":"2026-03-27 13:25:02","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":112577,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eRecurrence-free survival analysis in patients with AA versus PAA.\u003c/strong\u003e Kaplan-Meier survival curves showing the recurrence-free probability over time for the AA group (blue line) and the PAA (yellow line). The log-rank test P-value is shown. The number at risk at each time point, indicating the number of patients still under follow-up and event-free, is presented below the figure. AA, acute appendicitis; PAA, periappendiceal abscess.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9188553/v1/9ca7b2e42f3ba4842c2b90f5.png"},{"id":105571684,"identity":"cc7ec1fa-ac84-483d-a9cb-b9c56b4c00a9","added_by":"auto","created_at":"2026-03-27 13:24:02","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":141625,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eROC curve analyses of logistic regression models. \u003c/strong\u003e(A) ROC curve for discriminating AA from PAA (AUC = 0.640, 95% CI: 0.574-0.704). (B) ROC curve for predicting recurrence within the AA group (AUC = 0.707, 95% CI: 0.619-0.793). (C) ROC curve for predicting recurrence within the PAA group (AUC =0.782, 95% CI: 0.690-0.864). ROC, Receiver operating characteristic; AA, acute appendicitis; PAA, periappendiceal abscess; AUC, area under the receiver operating characteristic curve.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9188553/v1/58d5c6cfa6ab8e0a2fb691ea.png"},{"id":105571563,"identity":"22cb9bc5-be1c-4e2c-b327-a06dc20bd571","added_by":"auto","created_at":"2026-03-27 13:23:34","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":157080,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eForest plots of multivariate logistic regression analyses. Odds ratios (ORs) with 95% confidence intervals (CIs) are displayed. \u003c/strong\u003e(A) Factors independently associated with PAA versus AA. Reference: AA group. (B) Independent predictors of recurrence in patients with AA. (C) Independent predictors of recurrence in patients with PAA. AA, acute appendicitis; PAA, periappendiceal abscess.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9188553/v1/47f51b8895be4be43fc82611.png"},{"id":105574462,"identity":"f770c711-5e68-4cbc-8087-31096399e899","added_by":"auto","created_at":"2026-03-27 13:35:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1504730,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9188553/v1/2fc0e5a8-f11d-4c73-824e-30f893f94732.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Distinct Recurrence Patterns and Risk Factors Following Nonoperative Management of Acute Appendicitis versus Appendiceal Abscess in Children: Implications for Risk Stratification","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAcute appendicitis represents the most prevalent surgical emergency in the pediatric population, typically managed by prompt appendectomy to prevent perforation and its associated morbidity [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Laparoscopic appendectomy is thus considered the gold standard for uncomplicated cases [\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. However, this surgical paradigm is increasingly scrutinized. Pediatric surgery carries inherent risks, including anesthesia complications, postoperative intra-abdominal abscesses, and adhesion formation, which can be particularly consequential in young children [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Consequently, non-operative management (NOM) with antibiotics has emerged as a viable alternative for uncomplicated acute appendicitis (AA) [\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], with studies in both adults and children demonstrating comparable efficacy to surgery [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA more complex scenario arises in periappendiceal abscess (PAA), which complicates 2%\u0026ndash;10% of appendicitis cases [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Initial NOM\u0026mdash;often involving antibiotics with or without percutaneous drainage\u0026mdash;is standard, typically followed by an elective interval appendectomy [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. A critical, unresolved challenge common to both AA and PAA managed non-operatively is the risk of disease recurrence [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Crucially, robust evidence to guide the necessity of interval appendectomy after successful NOM remains lacking, leading to ongoing clinical controversy [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTherefore, to enable a risk-stratified clinical approach, this study aimed to directly compare long-term recurrence patterns and identify distinct predictors of recurrence following NOM in pediatric patients with AA versus those with PAA.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and participants\u003c/h2\u003e \u003cp\u003eWe conducted a retrospective cohort study of pediatric patients (aged\u0026thinsp;\u0026lt;\u0026thinsp;18 years) diagnosed with AA or PAA and initially managed non-operatively at the Children's Hospital of Chongqing Medical University between January 2020 and July 2024. Inclusion criteria were: (1) a clinical diagnosis of AA or PAA confirmed by ultrasound (US) findings (e.g., a dilated, non-compressible appendix\u0026thinsp;\u0026ge;\u0026thinsp;7 mm in diameter, presence of periappendiceal fluid collection, or an appendicolith) and supported by clinical signs (right lower quadrant tenderness) and laboratory inflammation (leukocyte count\u0026thinsp;\u0026gt;\u0026thinsp;10 \u0026times; 10⁹/L); (2) selection of NOM after informed consent from guardians; (3) clinical improvement with antibiotic therapy leading to discharge without emergency surgery. Exclusion criteria were: (1) incomplete clinical or follow-up data, or (2) pre-existing malignant disease.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eData collection and variables\u003c/h3\u003e\n\u003cp\u003eData were extracted from electronic medical records and included demographics (age, sex, weight), clinical presentation (symptom duration), admission diagnosis, and hospital course (length of stay). US findings (appendiceal diameter, presence of appendicolith or abscess) were recorded at admission and discharge. For the PAA subgroup, abscess volume (calculated using the ellipsoid formula: π/6 \u0026times; length \u0026times; width \u0026times; depth) and the abscess-to-weight ratio were determined. The primary outcome was disease recurrence, defined as a subsequent hospitalization for clinically and radiologically confirmed appendicitis requiring intervention (surgery or drainage) after initial successful NOM. For recurrent cases undergoing surgery, pathological reports were reviewed.\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eAnalyses were performed using R (v.4.5.2). Continuous data are presented as median (interquartile range, IQR) or mean (95% confidence interval, CI) based on distribution, assessed via the Shapiro\u0026ndash;Wilk test and quantile-quantile plots. Categorical data are presented as frequencies (percentages). Group comparisons (AA vs. PAA) for the primary outcome used Kaplan\u0026ndash;Meier survival analysis with the log-rank test, reported as hazard ratio (HR) with 95% CI. To identify independent predictors of recurrence, univariate logistic regression was first performed for all clinically relevant variables within the AA and PAA subgroups separately. Variables with \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.10 in univariate analysis were entered into a backward stepwise multivariate logistic regression model, with results expressed as adjusted odds ratios (aORs) with 95% CIs. A two-sided \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. Missing data were handled by multiple imputation with chained equations (MICE, m\u0026thinsp;=\u0026thinsp;5).\u003c/p\u003e \u003c/div\u003e\n\u003ch2\u003eEthical approval\u003c/h2\u003e\n\u003cp\u003eThe study protocol was approved by the Ethics Review Committee of the Children\u0026apos;s Hospital of Chongqing Medical University (Approval No.: 2026-LinYan 18). The requirement for individual informed consent was waived due to the retrospective design.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eStudy selection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBetween January 2020 and July 2024, 415 pediatric patients were initially identified as having received non-operative management for appendicitis. After applying exclusion criteria, six patients were removed: five due to loss to follow-up and one due to a coexisting malignant disease. Thus, the final analytic cohort comprised 409 patients, with a median follow-up of 38.8 months. Of these, 262 (64.1%) were diagnosed with AA and 147 (35.9%) with PAA. All diagnoses were clinically and radiologically confirmed. The study flow is detailed in \u003cstrong\u003eFigure 1\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBaseline characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe baseline demographic and clinical characteristics of the entire cohort (n=409) and the AA and PAA subgroups are summarized in \u003cstrong\u003eTable 1\u003c/strong\u003e. Overall, the median age was 9 years (IQR, 8\u0026ndash;10), median weight was 30.0 kg (IQR, 26.0\u0026ndash;34.0), 242 patients (59.2%) were male, and the median hospital stay was 6 days (IQR, 5\u0026ndash;7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFollow-up and recurrence\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe median follow-up time for the cohort was 38.8 months (IQR, 27.3\u0026ndash;54.5), estimated by the reverse Kaplan\u0026ndash;Meier method. Over this period, 78 of 409 patients (19.1%) experienced disease recurrence. The median time to recurrence was 137.5 days (IQR, 32.0\u0026ndash;321.8).\u003c/p\u003e\n\u003cp\u003eRecurrence-free survival differed significantly between the AA and PAA groups (log-rank \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001). Patients with PAA had a more than twofold higher risk of recurrence, with earlier onset (hazard ratio [HR] for PAA vs. AA, 2.09; 95% CI, 1.34\u0026ndash;3.26). The Kaplan\u0026ndash;Meier curves (\u003cstrong\u003eFigure 2\u003c/strong\u003e) illustrate this disparity: survival rates at 3, 6, and 12 months were 94.9%, 87.7%, and 84.6%, respectively, for the entire cohort, with a steeper initial decline in the PAA group. The curves plateaued after the first year. The number of patients at risk at each time point is provided beneath the figure.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSubgroup-specific recurrence patterns and pathology\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the AA subgroup (n\u0026nbsp;= 262), 39 patients (14.9%) recurred. Of these, 22 (56.4%) underwent interval appendectomy, while 17 continued NOM. One patient in the latter group had a second recurrence and proceeded to surgery; pathology indicated suppurative appendicitis.\u003c/p\u003e\n\u003cp\u003eIn the PAA subgroup (n\u0026nbsp;= 147), 39 patients (26.5%) recurred, and 23 (59.0%) underwent surgery. Three patients managed conservatively after the first recurrence experienced a second recurrence, all of whom subsequently underwent appendectomy. Pathological findings in these surgical cases were predominantly gangrenous appendicitis (2 of 3, 66.7%; the third showed chronic inflammation).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComparison between AA and PAA groups\u003c/strong\u003e\u003cbr\u003eIn the comparison between AA and PAA groups, univariate analysis identified several differentiating factors (\u003cstrong\u003eTable 1\u003c/strong\u003e). Multivariate logistic regression confirmed that a shorter length of stay, longer duration of pain, and the presence of an appendicolith were independently associated with PAA (all \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.05). The discriminative ability of this model for distinguishing AA from PAA was moderate (area under the receiver operating characteristic curve [AUC] = 0.640; \u003cstrong\u003eFigure 3A\u003c/strong\u003e). Key factors are visualized in a forest plot (\u003cstrong\u003eFigure 4A\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePredictors within the AA subgroup\u003c/strong\u003e\u003cbr\u003eWithin the AA subgroup (n = 262), univariate analysis identified appendiceal diameter and a negative pretreatment ultrasound as potential predictors of recurrence. In the adjusted multivariate model, a negative pretreatment ultrasound finding remained a significant independent protective factor (aOR = 0.21; 95% CI, 0.04\u0026ndash;0.97; P = 0.045) (\u003cstrong\u003eTable 2\u003c/strong\u003e). The model demonstrated fair predictive accuracy for recurrence (AUC = 0.707; \u003cstrong\u003eFigure 3B\u003c/strong\u003e). The corresponding forest plot is shown in \u003cstrong\u003eFigure 4B\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePredictors within the PAA subgroup\u003c/strong\u003e\u003cbr\u003eWithin the PAA subgroup (n = 147), age, weight, and a higher abscess-to-weight ratio at admission were associated with recurrence in univariate analysis. The final multivariate model identified three independent predictors: 1) the presence of an appendicolith (aOR = 2.98; 95% CI, 1.19\u0026ndash;7.84), 2) a higher abscess-to-weight ratio at admission (aOR = 1.12 per unit increase; 95% CI, 1.01\u0026ndash;1.26), and 3) a longer hospital stay, which was protective (aOR = 0.89 per day; 95% CI, 0.80\u0026ndash;0.97) (all P \u0026lt; 0.05) (\u003cstrong\u003eTable 3\u003c/strong\u003e). This model showed good discriminative ability (AUC = 0.782; \u003cstrong\u003eFigure 3C\u003c/strong\u003e), as further detailed in the forest plot (\u003cstrong\u003eFigure 4C\u003c/strong\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis retrospective study of pediatric patients with acute appendicitis, including both uncomplicated and complicated forms, found an overall recurrence rate of 19.1% after non-operative management, a figure consistent with previous reports\u0026nbsp;[18]. The recurrence rates observed in the acute appendicitis (14.9%) and periappendiceal abscess (26.5%) subgroups were also comparable to those documented in prior literature [7, 19]. The present analysis contributes a sizable cohort of children with imaging-confirmed diagnoses and offers a median follow-up duration that surpasses that of many previous studies.\u003c/p\u003e\n\u003cp\u003eComparative analysis revealed that patients with PAA had a significantly longer duration of pain and a higher prevalence of appendicolith than those with AA. These factors are well-established markers of disease severity and progression. The association between prolonged symptom duration and perforation or abscess formation is consistently reported\u0026nbsp;[20]. Similarly, an appendicolith acts as a nidus for obstruction and localized ischemia, substantially increasing the risk of complicated appendicitis [21, 22]. The observed longer hospital stay in the PAA group logically reflects the more intensive antibiotic regimens required for abscess management, rather than being an independent risk factor per se.\u003c/p\u003e\n\u003cp\u003eA key finding of our study is that, despite a higher observed recurrence rate in the PAA group, multivariate analysis did not identify PAA as an independent predictor of recurrence compared to AA. We propose two non-mutually exclusive explanations for this apparent paradox. First, the distinct pathophysiology of PAA may confer a degree of protection after initial healing. Following perforation, localized encapsulation by the omentum and adjacent bowel, accompanied by fibroblast activation and collagen deposition, leads to appendiceal fibrosis [23, 24]. This resultant fibrotic scar tissue forms a dense, avascular barrier that is less permeable to bacterial translocation and provides a suboptimal environment for acute inflammatory exacerbation after antibiotic therapy, potentially mitigating reinfection risk. Second, our institutional protocol recommending elective interval appendectomy ~3 months after successful NOM for PAA introduces a competing risk. This planned surgical intervention truncates the natural follow-up period for a subset of PAA patients, potentially censoring future recurrence events and thus attenuating the measured recurrence rate in this subgroup.\u003c/p\u003e\n\u003cp\u003eRegarding predictors within the AA subgroup, a negative pretreatment ultrasound finding emerged as a strong independent protective factor (aOR = 0.21; 95% CI, 0.04\u0026ndash;0.97), associated with a markedly lower recurrence rate (6.3% vs. 19.8%). This may point to divergent mechanisms of recurrence between AA and PAA. For AA, recurrence likely constitutes a \u003cem\u003ede novo\u003c/em\u003e inflammatory episode. Initial antibiotic therapy suppresses the acute infection but does not eliminate the underlying predisposition to luminal obstruction or dysregulated immune response within the appendix [25, 26]. Subsequent recurrence may thus represent a reactivation of this latent pathophysiology. In contrast, \u0026ldquo;recurrence\u0026rdquo; in PAA may be more accurately characterized as a persistence or recrudescence of the original infectious nidus. The pathological substrate is not a newly inflamed organ, but residual necrotic tissue, an appendicolith, or a contained micro-abscess. Clinical reappearance of symptoms may occur when host immune surveillance wanes or local containment fails [27].\u003c/p\u003e\n\u003cp\u003eWithin the PAA subgroup, our analysis identified three independent factors predictive of recurrence. First, the presence of an appendicolith was confirmed as a strong, independent risk factor (aOR = 2.98; 95% CI, 1.19-7.84), consistent with prior evidence [28, 29]. This finding elevates the appendicolith from a diagnostic feature to a key prognostic marker for NOM failure. Its role extends beyond initial luminal obstruction; as a persistent foreign body, it can impair abscess drainage, sustain a bacterial nidus, and hinder antibiotic efficacy, thereby complicating definitive non-operative cure. Second, we introduced the novel metric Abscess_to_weight_ratio_on_admission, which was independently associated with increased recurrence risk (aOR = 1.12 per unit increase). This ratio integrates the infectious burden (abscess volume) with a proxy for host resilience (body weight), providing a more holistic measure of disease severity than anatomical size alone. Its clinical relevance is intuitive: a larger abscess in a smaller child signifies a greater pathophysiological imbalance. Further prospective studies are warranted to validate its predictive utility and define optimal thresholds. Conversely, a longer hospital stay was protective (aOR = 0.89 per day). This underscores the principle that adequate initial therapy is paramount [30]. For PAA, an extended inpatient phase likely ensures complete intravenous antibiotic course, proper transition to oral therapy, and confirmation of clinical stability, thereby reducing the risk of premature treatment cessation and subsequent relapse.\u003c/p\u003e\n\u003cp\u003eKaplan\u0026ndash;Meier survival analysis revealed a distinct temporal pattern of recurrence between the two groups. Recurrence occurred significantly earlier in the PAA group (log-rank \u003cem\u003eP\u003c/em\u003e \u0026lt; 0.001), with nearly half of the events observed within the first month after treatment. In contrast, recurrences in the AA group were distributed more evenly over a prolonged period, from 3 months to 3 years. This pattern strongly suggests that early \u0026ldquo;recurrence\u0026rdquo; in PAA is closely linked to incomplete control of the initial infectious focus, whereas later recurrence in AA may represent a distinct pathophysiology. These findings have direct clinical implications. For patients with AA managed non-operatively, it is essential to emphasize the persistent, long-term risk of recurrence, which our data associate with a positive pretreatment ultrasound finding [31]. For patients with PAA, the first post-discharge month constitutes a critical high-risk window that warrants close clinical surveillance. The presence of an appendicolith\u0026mdash;a strong risk indicator in our cohort\u0026mdash;should prompt serious consideration of elective interval appendectomy after initial infection control [18, 32].\u003c/p\u003e\n\u003cp\u003ePathological examination of surgical specimens provided further mechanistic insight. Appendectomy after recurrence revealed a\u0026nbsp;predominance of suppurative appendicitis in the AA group, contrasting with gangrenous appendicitis in the PAA group\u0026nbsp;(P = 0.032). This histopathological divergence reinforces the proposed distinction in recurrence mechanisms. The suppurative pattern in AA is consistent with a\u0026nbsp;de novo inflammatory event, potentially driven by persistent anatomical or functional predispositions (e.g., luminal narrowing). Conversely, the necrotic, gangrenous pathology in PAA aligns with the concept of\u0026nbsp;incomplete eradication or recrudescence of the initial severe infection, an interpretation supported by the early recurrence pattern observed in this group.\u003c/p\u003e\n\u003cp\u003eAn interesting trend was observed in the AA subgroup: a larger appendiceal diameter at discharge was associated with a substantially increased recurrence risk, though this did not reach conventional statistical significance (OR = 3.76; 95% CI, 0.91\u0026ndash;17.8; \u003cem\u003eP\u003c/em\u003e = 0.068)\u0026nbsp;[33]. The large point estimate (OR = 3.76) suggests a\u0026nbsp;clinically meaningful effect, while the wide CI, spanning from near-null to very high risk, primarily reflects the limited sample size for this specific analysis. This result does not negate a potential association but underscores the need for future studies with larger cohorts to obtain a more precise estimate. Pathophysiologically, a persistently dilated appendix at discharge may signify\u0026nbsp;incomplete resolution of inflammation\u0026nbsp;or subclinical obstruction. Even after clinical and laboratory parameters normalize, residual wall edema, retained secretions, or micro-appendicoliths could sustain luminal patency, creating an anatomical predisposition for the reactivation of acute inflammation.\u003c/p\u003e\n\u003cp\u003eSeveral limitations of this study warrant consideration. First, its retrospective, single-center design is susceptible to selection bias and unmeasured confounding. Although we adjusted for known covariates, residual confounding from factors such as microbial profiles or outpatient antibiotic adherence cannot be ruled out. Second, despite efforts to contact patients, loss to follow-up and reliance on outside-hospital records may have led to incomplete outcome ascertainment. Third, the sample size, particularly within certain risk-stratified subgroups (e.g., those with an appendicolith), limited the statistical power and precision of some estimates, as reflected in wide confidence intervals; these findings require validation in larger cohorts. Finally, clinical management\u0026mdash;including antibiotic choice, duration, and the use/timing of drainage\u0026mdash;was guided by institutional pathways rather than a uniform protocol. While this reflects real-world practice, it may affect the generalizability of results to centers with differing treatment strategies.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, this study delineates distinct recurrence patterns and risk profiles following NOM of pediatric AA and PAA. Our findings demonstrate that recurrence in PAA is an early event, concentrated within the first month and indicative of initial infection control failure, driven by factors such as the presence of an appendicolith and a higher abscess-to-weight ratio. In contrast, recurrence in AA follows a protracted, long-term course, aligning with de novo inflammatory episodes and associated with a positive pretreatment ultrasound finding. These insights support a risk-stratified management paradigm. For PAA, particularly in cases with an appendicolith, management should prioritize intensified early surveillance and strong consideration of elective interval appendectomy. For AA, especially when ultrasound is negative, standard NOM with long-term follow-up is appropriate, with care plans guided by shared decision-making. This study affirms the feasibility of NOM in children while highlighting the need for tailored strategies based on disease phenotype. Future prospective studies are needed to validate these predictors and to integrate them into robust clinical prediction models.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e None.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there are no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study, which involved the analysis of retrospective patient medical record data, was approved by the Ethics Committee of the Children\u0026rsquo;s Hospital of Chongqing Medical University (Approval No.: 2026-LinYan 18). The requirement for informed consent was waived by the same ethics committee due to the retrospective nature of the study. All procedures were performed in accordance with the ethical standards of the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate:\u003c/strong\u003e Not applicable. This study did not involve direct human participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contribution：\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZhendi Tang: Conceptualization, Methodology, Validation, Formal analysis, Investigation, Data Curation, Writing \u0026ndash; Original Draft, Visualization.\u003c/p\u003e\n\u003cp\u003ePengcheng Luo: Methodology, Software, Validation, Investigation, Writing \u0026ndash; Review \u0026amp; Editing.\u003c/p\u003e\n\u003cp\u003eJiajia Zhou: Resources, Data Curation, Writing \u0026ndash; Review \u0026amp; Editing, Supervision.\u003c/p\u003e\n\u003cp\u003eQuan Kang: Formal analysis, Writing \u0026ndash; Review \u0026amp; Editing, Project administration.\u003c/p\u003e\n\u003cp\u003eDengliang Wang (Corresponding Author): Conceptualization, Resources, Writing \u0026ndash; Review \u0026amp; Editing, Supervision, Project administration, Funding acquisition.\u003c/p\u003e\n\u003cp\u003eAll authors have read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability declaration:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analyzed during this study are included in the Supplementary Material of this article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSt\u0026ouml;\u0026szlig; C, et al. Acute Appendicitis: Trends in Surgical Treatment\u0026mdash;A Population-Based Study of Over 800 000 Patients. Dtsch Arztebl Int. 2021;118(14):244\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKumar SS, et al. SAGES guideline for the diagnosis and treatment of appendicitis. Surg Endosc. 2024;38(6):2974\u0026ndash;94.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBachur RG, Lipsett SC, Monuteaux MC. Outcomes Nonoperative Manage Uncomplicated Appendicitis Pediatr, 2017. 140(1).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrucchi F, et al. A meta-analysis and trial sequential analysis comparing nonoperative versus operative management for uncomplicated appendicitis: a focus on randomized controlled trials. World J Emerg Surg. 2024;19(1):2.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eH\u0026aring;kanson CA, Fredriksson F, Lilja HE. 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Ann Surg. 2019;270(6):1028\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou S et al. Early versus delayed appendicectomy for appendiceal phlegmon or abscess. Cochrane Database Syst Rev, 2024. 5(5): p. Cd011670.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkingboye AA, et al. Early versus delayed (interval) appendicectomy for the management of appendicular abscess and phlegmon: a systematic review and meta-analysis. Langenbecks Arch Surg. 2021;406(5):1341\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkbar HF, et al. The Efficacy of Conservative Management in Uncomplicated Acute Appendicitis - A Single-Center Retrospective Study. Cureus. 2022;14(12):e32606.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSakorafas GH, et al. Interval routine appendectomy following conservative treatment of acute appendicitis: Is it really needed. World J Gastrointest Surg. 2012;4(4):83\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLugo JZ, et al. Can interval appendectomy be justified following conservative treatment of perforated acute appendicitis? J Surg Res. 2010;164(1):91\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAkbarpoor F, et al. Conservative Management of Pediatric Patients With Appendicolith Appendicitis Versus Non-appendicolith Appendicitis: A Systematic Review and Meta-analysis. J Pediatr Surg. 2025;60(4):162175.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDing YB, Wang WN, Zhan XL. Ultrasound-Guided Percutaneous Catheter Drainage in Periappendiceal abscess Management: Retrospective Insights. Pak J Med Sci. 2025;41(2):564\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNelson DS, Bateman B, Bolte RG. Appendiceal perforation in children diagnosed in a pediatric emergency department. Pediatr Emerg Care. 2000;16(4):233\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlaedeen DI, Cook M, Chwals WJ. Appendiceal fecalith is associated with early perforation in pediatric patients. J Pediatr Surg. 2008;43(5):889\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang Y, et al. Predictive model for identification of gangrenous or perforated appendicitis in adults: a multicenter retrospective study. BMC Gastroenterol. 2024;24(1):355.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMostyka M, et al. Interval Appendectomy Specimens. Arch Pathol Lab Med. 2022;147(5):546\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuo G, Greenson JK. Histopathology of interval (delayed) appendectomy specimens: strong association with granulomatous and xanthogranulomatous appendicitis. Am J Surg Pathol. 2003;27(8):1147\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarvalho N et al. Compilation of Evidence Supporting the Role of a T Helper 2 Reaction in the Pathogenesis of Acute Appendicitis. Int J Mol Sci, 2024. 25(8).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTsuji M, et al. New insights into the pathogenesis of appendicitis based on immunocytochemical analysis of early immune response. J Pediatr Surg. 1990;25(4):449\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTaleb M, et al. Simplification of first-line antibacterial regimen for complicated appendicitis in children is associated with better adherence to guidelines and reduced use of antibiotics. Int J Antimicrob Agents. 2018;52(2):293\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCastell\u0026oacute; Gonz\u0026aacute;lez M, et al. Predictors of recurrent appendicitis after non-operative management of children with perforated appendicitis presenting with an appendicular inflammatory mass. Arch Dis Child. 2014;99(2):154\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEin SH, Langer JC, Daneman A. Nonoperative management of pediatric ruptured appendix with inflammatory mass or abscess: presence of an appendicolith predicts recurrent appendicitis. J Pediatr Surg. 2005;40(10):1612\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFawley J, Gollin G. Expanded utilization of nonoperative management for complicated appendicitis in children. Langenbecks Arch Surg. 2013;398(3):463\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJimbo K, et al. Is a pediatrician performed gray scale ultrasonography with power Doppler study safe and effective for triaging acute non-perforated appendicitis for conservative management? J Pediatr Surg. 2016;51(12):1952\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang HL, et al. Nonoperative management of appendiceal phlegmon or abscess with an appendicolith in children. J Gastrointest Surg. 2013;17(4):766\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark HC, Kim MJ, Lee BH. The outcome of antibiotic therapy for uncomplicated appendicitis with diameters\u0026thinsp;\u0026le;\u0026thinsp;10 mm. Int J Surg. 2014;12(9):897\u0026ndash;900.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cdiv class=\"gridtable\"\u003e\n \u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eUnivariate and multivariate analyses of clinical characteristics in AA and PAA.\u003c/span\u003e AA, acute appendicitis; PAA, periappendiceal abscess.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVariables\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eAcute appendicitis\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eN\u0026thinsp;=\u0026thinsp;262\u003csup\u003e1\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePeriappendiceal abscess\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eN\u0026thinsp;=\u0026thinsp;147\u003csup\u003e1\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eUnivariable\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMultivariable\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003ep-value\u003c/span\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eOR (95% CI)\u003c/span\u003e\u003csup\u003e3\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003ep-value\u003c/span\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eGender\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.060\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.300\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e164 (63%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e78 (53%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.59(0.23\u0026ndash;1.49)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eFemale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e98 (37%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e69 (47%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.00(Reference)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAge\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e8.98\u0026thinsp;\u0026plusmn;\u0026thinsp;3.06\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6.88\u0026thinsp;\u0026plusmn;\u0026thinsp;3.34\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.85(0.66\u0026ndash;1.08)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.200\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eWeight\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e32.92\u0026thinsp;\u0026plusmn;\u0026thinsp;13.73\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e26.42\u0026thinsp;\u0026plusmn;\u0026thinsp;13.84\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.99(0.94\u0026ndash;1.06)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.900\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLength_of_stay\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4.05\u0026thinsp;\u0026plusmn;\u0026thinsp;1.80\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e12.22\u0026thinsp;\u0026plusmn;\u0026thinsp;5.27\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.96(1.64\u0026ndash;2.44)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eDuration_of_pain\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.79\u0026thinsp;\u0026plusmn;\u0026thinsp;2.77\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7.14\u0026thinsp;\u0026plusmn;\u0026thinsp;3.41\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.36(1.21\u0026ndash;1.57)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAppendicolith\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7 (2.7%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e49 (34%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5.30(1.17\u0026ndash;27.7)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.030\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eRecurrence\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e39 (15%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e39 (27%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.004\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.71(0.60\u0026ndash;4.77)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.300\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eHistopathology\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.032\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSimple appendicitis\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1 (4.5%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2 (8.7%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSuppurative appendicitis\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e14 (64%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6 (26%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eGangrenous appendicitis\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7 (32%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e15 (65%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003csup\u003e1\u003c/sup\u003en (%); Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003csup\u003e2\u003c/sup\u003ePearson\u0026apos;s Chi-squared test; Wilcoxon rank sum test; Fisher\u0026apos;s exact test\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e\u003csup\u003e3\u003c/sup\u003eAbbreviations: CI\u0026thinsp;=\u0026thinsp;Confidence Interval, OR\u0026thinsp;=\u0026thinsp;Odds Ratio\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\u0026nbsp;\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eUnivariate and multivariate analyses of children with AA: recurrence versus non-recurrence.\u003c/span\u003e AA, acute appendicitis.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVariables\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNon-recurrence\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eN\u0026thinsp;=\u0026thinsp;223\u003csup\u003e1\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eRecurrence\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eN\u0026thinsp;=\u0026thinsp;39\u003csup\u003e1\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eUnivariable\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMultivariable\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003ep-value\u003c/span\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eOR (95% CI)\u003c/span\u003e\u003csup\u003e3\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003ep-value\u003c/span\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eGender\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.198\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.300\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e136 (61%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e28 (72%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.54(0.70\u0026ndash;3.54)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eFemale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e87 (39%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e11 (28%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.00(Reference)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAge\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e8.96\u0026thinsp;\u0026plusmn;\u0026thinsp;3.05\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e9.12\u0026thinsp;\u0026plusmn;\u0026thinsp;3.13\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.623\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.09(0.88\u0026ndash;1.35)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.400\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eWeight\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e32.94\u0026thinsp;\u0026plusmn;\u0026thinsp;13.90\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e32.81\u0026thinsp;\u0026plusmn;\u0026thinsp;12.85\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.833\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.98(0.93\u0026ndash;1.03)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.500\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLength_of_stay\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3.96\u0026thinsp;\u0026plusmn;\u0026thinsp;1.69\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4.56\u0026thinsp;\u0026plusmn;\u0026thinsp;2.29\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.126\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.12(0.93\u0026ndash;1.36)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.200\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eDuration_of_pain\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.75\u0026thinsp;\u0026plusmn;\u0026thinsp;2.83\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2.06\u0026thinsp;\u0026plusmn;\u0026thinsp;2.42\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.583\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAppendicolith\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6 (2.7%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1 (2.6%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026gt;\u0026thinsp;0.999\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAppendiceal_diameter_on_admission\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.38\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.005\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.31(0.04\u0026ndash;2.15)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.200\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAppendiceal_diameter_at_discharge\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.23\u0026thinsp;\u0026plusmn;\u0026thinsp;0.30\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.41\u0026thinsp;\u0026plusmn;\u0026thinsp;0.33\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u0026lt;\u0026thinsp;0.001\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3.76(0.91\u0026ndash;17.8)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.068\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eUltrasound_negative\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e89 (40%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6 (15%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.003\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.21(0.04\u0026ndash;0.97)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.045\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003csup\u003e1\u003c/sup\u003e n (%); Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003csup\u003e2\u003c/sup\u003eWilcoxon rank sum test; Pearson\u0026apos;s Chi-squared test; Fisher\u0026apos;s exact test\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e\u003csup\u003e3\u003c/sup\u003eAbbreviations: CI\u0026thinsp;=\u0026thinsp;Confidence Interval, OR\u0026thinsp;=\u0026thinsp;Odds Ratio\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv category=\"SREP\" id=\"15\" ruleid=\"IdentifyCAMTerms_01\" status=\"attended\" values=\"holistic\" class=\"btn-xs-small Annotation tooltipped\" data-position=\"top\" data-tooltip=\"\"\u003e\u0026nbsp;\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eUnivariate and multivariate analyses of children with PAA: recurrence versus non-recurrence.\u003c/span\u003e PAA, periappendiceal abscess.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVariables\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eNon-recurrence\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eN\u0026thinsp;=\u0026thinsp;108\u003csup\u003e1\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eRecurrence\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eN\u0026thinsp;=\u0026thinsp;39\u003csup\u003e1\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eUnivariable\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMultivariable\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003ep-value\u003c/span\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e\n \u003cth align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eOR (95% CI)\u003c/span\u003e\u003csup\u003e3\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003ep-value\u003c/span\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eGender\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.388\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.400\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eMale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e55 (51%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e23 (59%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.42(0.60\u0026ndash;3.46)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eFemale\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e53 (49%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e16 (41%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.00(Reference)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAge\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7.26\u0026thinsp;\u0026plusmn;\u0026thinsp;3.38\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5.82\u0026thinsp;\u0026plusmn;\u0026thinsp;3.01\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.010\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.14(0.84\u0026ndash;1.63)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.400\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eWeight\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e28.39\u0026thinsp;\u0026plusmn;\u0026thinsp;14.67\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e20.95\u0026thinsp;\u0026plusmn;\u0026thinsp;9.39\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.003\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.92(0.82-1.00)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.110\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eLength_of_stay\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e12.61\u0026thinsp;\u0026plusmn;\u0026thinsp;5.35\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e11.13\u0026thinsp;\u0026plusmn;\u0026thinsp;4.96\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.132\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.89(0.80\u0026ndash;0.97)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.014\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eDuration_of_pain\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7.19\u0026thinsp;\u0026plusmn;\u0026thinsp;3.11\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7.01\u0026thinsp;\u0026plusmn;\u0026thinsp;4.17\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.693\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAppendicolith\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e32 (30%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e17 (45%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.090\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2.98(1.19\u0026ndash;7.84)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.022\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eCondition_at_discharge\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e72 (68%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e21 (55%)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.161\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAbscess_to_weight_ratio_on_admission\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3.70\u0026thinsp;\u0026plusmn;\u0026thinsp;3.16\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5.84\u0026thinsp;\u0026plusmn;\u0026thinsp;5.02\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.003\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.12(1.01\u0026ndash;1.26)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.039\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eAbscess_to_weight_ratio_at_discharge\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.62\u0026thinsp;\u0026plusmn;\u0026thinsp;0.97\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.74\u0026thinsp;\u0026plusmn;\u0026thinsp;1.79\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.293\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colname=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eDischarge_to_admission_\u003c/span\u003e\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003cspan type=\"Bold\" class=\"Bold\" name=\"Emphasis\"\u003eabscess_ratio\u003c/span\u003e\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c2\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.28\u0026thinsp;\u0026plusmn;\u0026thinsp;0.59\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c3\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.14\u0026thinsp;\u0026plusmn;\u0026thinsp;0.27\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c4\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.095\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c6\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.35(0.06\u0026ndash;1.35)\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" colname=\"c7\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.200\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003csup\u003e1\u003c/sup\u003e n (%); Mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e\u003csup\u003e2\u003c/sup\u003eWilcoxon rank sum test; Pearson\u0026apos;s Chi-squared test\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\"\u003e\u003csup\u003e3\u003c/sup\u003eAbbreviations: CI\u0026thinsp;=\u0026thinsp;Confidence Interval, OR\u0026thinsp;=\u0026thinsp;Odds Ratio\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\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":"bmc-pediatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bped","sideBox":"Learn more about [BMC Pediatrics](http://bmcpediatr.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bped/default.aspx","title":"BMC Pediatrics","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Acute appendicitis, Periappendiceal abscess, Conservative treatment, Recurrence, Risk factors, Children","lastPublishedDoi":"10.21203/rs.3.rs-9188553/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9188553/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo compare recurrence patterns and identify risk factors after nonoperative management of acute appendicitis (AA) and periappendiceal abscess (PAA) in children.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eIn this retrospective cohort study, children (\u0026lt;\u0026thinsp;18 years) with AA or PAA (defined by imaging) and treated nonoperatively (Jan 2020\u0026ndash;Jul 2024) were included. The primary outcome was clinical recurrence. Risk factors were identified using multivariable logistic regression and Kaplan\u0026ndash;Meier analysis.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAmong 409 patients (median follow-up 38.8 months), recurrence was higher in the PAA group than in the AA group (26.5% vs. 14.9%), with earlier recurrence (HR 2.09, 95% CI 1.34\u0026ndash;3.26; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In the PAA group, the presence of an appendicolith (adjusted odds ratio [aOR] 2.98, 95% CI 1.19\u0026ndash;7.84) and a higher abscess-to-weight ratio at admission (aOR 1.12 per unit, 95% CI 1.01\u0026ndash;1.26) were independent risk factors for recurrence, whereas a longer length of hospital stay was protective (aOR 0.89 per day, 95% CI 0.80\u0026ndash;0.97). In the AA group, a negative pretreatment ultrasound finding was protective (OR 0.21, 95% CI 0.04\u0026ndash;0.97). Surgical pathology of recurrent cases showed a predominance of gangrenous appendicitis in the PAA group versus suppurative appendicitis in the AA group (p\u0026thinsp;=\u0026thinsp;0.032).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eFollowing nonoperative management, PAA is associated with a high risk of early recurrence, driven by appendicolith and greater infectious burden, which justifies enhanced early surveillance and consideration of interval appendectomy. Recurrence risk in AA is lower and more protracted, particularly when ultrasound is negative. These findings support a risk-stratified approach to management.\u003c/p\u003e","manuscriptTitle":"Distinct Recurrence Patterns and Risk Factors Following Nonoperative Management of Acute Appendicitis versus Appendiceal Abscess in Children: Implications for Risk Stratification","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-27 12:29:53","doi":"10.21203/rs.3.rs-9188553/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-13T05:15:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6001605601530730522749571555671028813","date":"2026-05-07T22:53:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"137010034542713087236819730937680219168","date":"2026-05-07T00:09:00+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"66657279327253272878739443955709099658","date":"2026-03-28T05:08:45+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-25T07:54:50+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-24T06:47:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-24T06:39:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-24T06:39:13+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pediatrics","date":"2026-03-22T01:49:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pediatrics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bped","sideBox":"Learn more about [BMC Pediatrics](http://bmcpediatr.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bped/default.aspx","title":"BMC Pediatrics","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8e3ee3df-c4ea-4b97-a780-2fb9757aeeb3","owner":[],"postedDate":"March 27th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-13T05:15:23+00:00","index":88,"fulltext":""},{"type":"reviewerAgreed","content":"6001605601530730522749571555671028813","date":"2026-05-07T22:53:57+00:00","index":87,"fulltext":""},{"type":"reviewerAgreed","content":"137010034542713087236819730937680219168","date":"2026-05-07T00:09:00+00:00","index":86,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-27T12:29:53+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-27 12:29:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9188553","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9188553","identity":"rs-9188553","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}