Assessing the risk of gastrointestinal perforation associated with COVID-19: a self-controlled case series study

Although some case reports have reported gastrointestinal perforation after COVID-19, epidemiologic studies investigating this association are scarce. We aimed to assess the risk of gastrointestinal perforation associated with COVID-19. We conducted a self-controlled case series (SCCS) study using a Japanese nationwide, large-scale claims database. We identified patients diagnosed with COVID-19 between March 2020 and October 2022 who had undergone surgery for gastrointestinal perforation. Conditional Poisson regression was used to estimate the incidence rate ratio (IRR) and 95% confidence intervals (CIs) of gastrointestinal perforation during the 4-week risk period compared with the control period. Our SCCS study included 276 patients. The IRR for gastrointestinal perforation was 6.62 (95% CI, 3.52-12.47) for the first week, 3.27 (95% CI, 1.51-7.09) for the second week, and 1.45 (95% CI, 0.63-3.33) for the third and fourth weeks following COVID-19. The risk was lower in female patients than in male patients. In a subgroup analysis, the results were consistent regardless of age. This study suggests a significant association between COVID-19 and gastrointestinal perforation, particularly during the first 2 weeks. These findings highlight the need to recognize COVID-19 as a risk factor for gastrointestinal perforation. Trial registration: This research did not undergo prior registration in an independent registry.