Associations Between Time-To-Surgery and Postoperative Length of Stay and Complications in Patients With Acute Appendicitis.

INTRODUCTION: Acute appendicitis is a common surgical emergency. The optimal time-to-surgery interval remains debated, as studies reported increased complication risk beyond 12 or 24 hours respectively. We hypothesized that time-to-surgery of up to 24 hours after admission was not associated with increased postoperative length of stay (LOS) or complications. METHODS: This retrospective observational cohort study included adults and adolescents (≥ 15 years) undergoing laparoscopic appendectomy from January 2017-July 2025 in the Capital and the Zealand Regions of Denmark. Data were extracted from the Electronic Health Record system. The primary exposure was time-to-surgery intervals. Primary outcome was postoperative LOS. Secondary outcomes were 30-day postoperative complications. Subgroup analyses were performed for uncomplicated/complicated appendicitis. All outcomes were evaluated by multivariable regression models adjusted for predefined confounders. RESULTS: Of 25,417 laparoscopic appendectomies, 19,089 met eligibility criteria. Compared with time-to-surgery < 8 hours, postoperative LOS was reduced when time-to-surgery was 8-16 hours (mean difference -2.29 hours, 95% CI: -3.85 to -0.73) and 16-24 hours (-3.92 hours, 95% CI: -6.05 to -1.78). Compared with time-to-surgery < 8 hours, odds of postoperative complications were reduced for time-to-surgery up to 24 hours, whereas ≥ 36 hours was associated with increased odds (OR 1.57, 95% CI: 1.13 to 2.18). In complicated appendicitis, time-to-surgery 24-36 hours was associated with decreased postoperative LOS (-13.0 hours, 95% CI: -22 to -3.6). CONCLUSION: Time-to-surgery of up to 24 hours was not associated with increased postoperative LOS or complications. In contrast, we observed a protective association driven by complicated appendicitis, potentially reflecting effective clinical triage.