Correlation between surgical mortality for perforated peritonitis and days of the week for operations: A retrospective study using the Japanese National Clinical Database

Background: The association between weekend interventions and poor outcomes is termed the “weekend effect.” This retrospective study investigated whether the weekend effect exists in the surgical treatment of acute diffuse peritonitis due to gastrointestinal perforation. Methods: Patients (n = 16,209) who underwent operation for acute diffuse peritonitis during 2016–2017 were included and grouped depending on the perforation site. Using 23 variables, we performed hierarchical logistic regression analysis and calculated odds ratios for surgical mortality. Results: Surgical mortality rates were 8.8%, 15.0%, and 14.1% for patients with gastroduodenal, small bowel, and large bowel perforations, respectively. Unadjusted odds ratios for surgical mortality differed significantly on Wednesdays only for patients with large bowel perforation (odds ratio: 0.772, 95% confidence interval: 0.613–0.972, P = 0.03). However, there was no significant difference in adjusted odds ratios. Conclusion: The quality of emergency surgical treatment is uniform in Japan throughout the week in terms of mortality.