Introduction: Intra-abdominal abscess (IAA) after perforated appendicitis is associated with increased healthcare costs. In 2016, our center conducted a pilot randomized control trial (RCT) in which 100 children (age 2-17) with perforated appendicitis were randomized to intra-abdominal irrigation with povidone-iodine (PVI) during appendectomy or no irrigation. We observed an 89% probability that PVI irrigation reduced the rate of IAA (Bayesian Relative Risk: 0.72 [95% credible interval (CrI), 0.38-1.23]). We hypothesized that PVI irrigation is economically dominant by also reducing treatment costs, in addition to reducing the rate of IAA. Methods: A secondary economic evaluation of the RCT was performed from the healthcare system perspective. Costs for index admissions and appendicitis-related emergency room visits and readmissions within 30 postoperative days were inflated to 2019 US dollars. One patient with simple appendicitis who was inadvertently randomized was excluded from the primary cost analysis. Cost differences between PVI and no irrigation were assessed using frequentist and Bayesian generalized linear models with a log link and gamma distribution. Bayesian analysis used a neutral prior centered at a cost ratio of 1.0 (95% CrI 0.3-3.3). Results: Of 99 included patients, 50 received PVI irrigation. Baseline characteristics were similar between groups. Thirty-day mean total costs in the PVI group were $16,555 (95% CI $15,047 to $18,062) versus $18,800 in the no irrigation group (95% CI $17,070 to $20,529), with a mean absolute difference of $2,444 less per patient in the PVI group (95% CI -$4,539 to $49, Table). There was a 97% probability that PVI reduces 30-day total costs (Bayesian cost ratio: 0.88 [95% CrI 0.8-1.0]). Conclusions: In this pilot RCT, intra-abdominal irrigation with PVI likely reduced both the 30-day IAA rate and healthcare system costs, suggesting cost-effectiveness dominance. Additional trials in other centers are needed to confirm the benefits of PVI irrigation.

Mean 30-day hospital costs of randomized trial participants

† All costs were inflated to 2019 US dollars based on the Consumer Price Index for medical services. * Mean cost difference of pediatric perforated appendicitis patients randomized to receive povidone-iodine intra-abdominal irrigation during appendectomy (intervention) versus those randomized to receive no irrigation (control).