Importance of nighttime emergency colorectal surgery: a retrospective observational study at a regional emergency medical center

To evaluate the association between nighttime emergency department (ED) presentation and postoperative outcomes following emergency colorectal resection. Patients who underwent emergency colorectal resection within 24 h of ED presentation at a regional emergency medical center between June 2009 and February 2023 were retrospectively reviewed. Patients were categorized according to ED presentation time as daytime (08:00–18:00) or nighttime (18:00–08:00). The primary outcome was 30-day mortality. Multivariable logistic regression, propensity score matching (PSM), and inverse probability of treatment weighting (IPTW) analyses were performed. A total of 279 patients were included (159 daytime and 120 nighttime presentations). Thirty-day mortality was significantly higher in the nighttime group than in the daytime group (20.0% vs. 8.8%, P = 0.012), as was the incidence of severe complications (Clavien–Dindo grade ≥ III; 34.2% vs. 16.4%, P = 0.001). In multivariable analyses, nighttime ED presentation was associated with higher odds of 30-day mortality (OR 2.41, 95% CI 1.07–5.42; P = 0.034) and severe complications (OR 2.56, 95% CI 1.32–4.96; P = 0.006). After PSM, nighttime presentation was not significantly associated with 30-day mortality (OR 1.75, 95% CI 0.73–4.17; P = 0.207) but remained associated with severe complications (OR 2.44, 95% CI 1.13–5.31; P = 0.024). Similarly, in the IPTW analysis, the association with 30-day mortality was not statistically significant (OR 1.96, 95% CI 0.94–4.09; P = 0.072), whereas the association with severe complications remained significant (OR 2.06, 95% CI 1.15–3.70; P = 0.015). Nighttime ED presentation was consistently associated with an increased risk of severe postoperative complications following emergency colorectal resection, including after adjustment for measured baseline differences using propensity score–based analyses. Although higher 30-day mortality was observed among nighttime patients, this association was attenuated and was not statistically significant after PSM or IPTW.