Abstract
Importance: Superficial surgical site infection (SSI) is common in appendectomy for complicated appendicitis. Delayed primary wound closure (DPC) is preferentially used over primary closure (PC) but its efficacy is still controversial. Objective: To compare superficial SSI rates between DPC and PC for complicated appendicitis. Design, setting, participants: A multicenter, randomized controlled trial of complicated appendicitis, involving 607 adult patients from 6 hospitals in Thailand between November 2012 to February 2016. This included cases of gangrenous appendicitis, as well as rupture. Intervention: Patients were randomized to PC (i.e., immediately wound closure after operation) or DPC (i.e., wound closure at postoperative days 3 to 5). Main outcome and measure: Superficial SSI, as defined by the Center for Disease Control criteria. Secondary outcomes included postoperative pain, length of stay, recovery time, quality of life and cost of treatment. Results: Among 303 and 304 patients in the PC and DPC groups, 5 and 4 patients were lost follow up respectively, leaving 300 and 298 patients for intention-to-treat (ITT) analysis. The superficial SSI rate was lower in the PC than DPC group (i.e., 7.3% (95% CI: 4.4, 10.3) versus 10% (6.6, 13.3)) with a risk difference (RD) of -2.7% (-7.1%, 1.9%). Protocol violations occurred in 15 patients (i.e., 9 in PC and 6 in DPC groups). RDs for per-protocol and as-treated approaches were respectively -1.9% (-6.5%, 2.6%) and -1.1% (-5.6%, 3.4%). In addition, a counterfactual approach using instrumental-variable analysis yielded a RD of -3.6% (-8.3%, 1.1%). Postoperative pain, length of stay, recovery times, and quality of life were not significantly different between groups with corresponding RDs of 0.3 (-2.5, 3.0), -0.1 (-0.5, 0.3), -0.2 (-0.8, 0.4), and 0.02 (-0.01, 0.04). However, costs for DPC were 2083 (1410, 2756) Baht higher than PC (~$60 USD or 56 euros). Conclusion and Relevance: Superficial SSI rates were slightly lower for PC than DPC groups, although this did not reach statistical significance. Costs were modestly but statistically significantly lower for the PC group. Trial Registration: clinicaltrial.org Identifier: NCT01659983
