Association between surgical volume and postoperative complications following posterior deep infiltrating endometriosis surgery: A nationwide population-based study.

Abstract

Deep infiltrating endometriosis predominantly affects the posterior pelvic compartment and often requires complex surgical procedures, which are associated with a significant risk of postoperative complications. Limited evidence is available regarding the influence of center case volume on surgical outcomes. To assess the association between center case volume and the risk of severe postoperative complications following posterior deep infiltrating endometriosis surgery during the initial hospital stay or upon readmission occurring within 90 days. A population-based cohort study using the French national medico-administrative database (Program of Medicalization of Information Systems - a comprehensive nationwide hospitalization database based on diagnosis-related groups). The study included all hospital stays for posterior deep-infiltrating endometriosis surgery in France between January 1, 2021, and December 31, 2023. The primary outcome was the occurrence of at least one severe postoperative complication during the initial hospital stay or during a readmission within 90 days. Postoperative complications were defined using the International Classification of Diseases, Tenth Revision (ICD-10) codes and classified according to the Clavien-Dindo classification; severe postoperative complications were defined as grade III-V. Annual hospital surgical volume for posterior deep infiltrating endometriosis was categorized into two levels based on spline function visualization derived from successive logistic regression models. The association between hospital volume and outcomes was assessed using multivariate logistic regression with generalized estimating equations to account for the hospital-cluster effect, adjusting for all covariates (i.e., radical or conservative surgery, surgical approach, patient age, previous endometriosis surgery within 3 years, presence of surgical procedures associated, Charlson Comorbidity index [0 vs ≥1], and type of healthcare institution). The intraclass correlation coefficient was calculated to estimate the percentages of complication variability explained by the center effect. Results are presented as adjusted odds ratios (ORs), with their 95% confidence intervals (95% CIs) and p-values. A total of 15,364 hospital stays for posterior deep-infiltrating endometriosis surgery were reported. Among these, 658 (4.3%) involved at least one severe postoperative complication (Clavien grade III-V). The optimal cut point was 40 hospital stays per year. Centers with fewer than 40 hospital stays per year had a severe postoperative complication rate of 318/6,005 (5.3%), compared with 340/9,359 (3.6%) in centers with ≥40 hospital stays per year. In multivariable analysis, a surgical volume ≥40 hospital stays per year was associated with a reduced risk of severe complications (aOR, 0.83; 95% CI, 0.70-0.99; p = 0.03). A center's surgical case volume has a significant positive impact on patient outcomes after posterior deep infiltrating endometriosis surgery. The rates of severe postoperative complications or readmissions within 90 days decreased as center case volume increased.