Supplementary Material for: Inflammatory Bowel Disease Incidence following COVID-19: A Systematic Review and Meta-Analysis

Background: A surge of cases of autoimmune and inflammatory diseases, such as inflammatory bowel disease (IBD), have been reported after coronavirus disease 2019 (COVID19).
Objective: To assess whether COVID19 has a role in IBD risk.
Methods: We searched MEDLINE (PubMed), Cochrane Library and OpenGrey databases up to October 30, 2025, for studies evaluating the incidence of IBD following COVID-19 infection. PROSPERO ID: CRD42024534916.
Results: After a full text review of 84 manuscripts, a total of 8 studies were used in the qualitative analysis. The studies were conducted between 2023 and 2024 and included in total 28,659,801 people, 8,560,826 of which were previously infected with COVID19 and 20,098,975 that were served as healthy controls. The results from the pooled synthesis of 6 studies indicate a 39% higher incidence of IBD in people that were previously infected with COVID19 (RR 1.39, 95% CI [1.12-1.74], p = 0.003, I2 = 97%). Furthermore, from the pooled analysis of 4 eligible studies, a higher incidence of new ulcerative colitis cases following COVID19 was observed (RR 1.25, 95% CI [1.17-1.33], p < 0.00001, I2 = 0%). On the contrary, no difference was observed in Crohn’s disease incidence between COVID19 and non-COVID19 patients (RR 1.23 95% CI [0.88, 1.72], p = 0.22, I2 = 91%).
Conclusions: The findings of the present meta-analysis suggest an increased risk of IBD after COVID19 infection. Although this is more evident regarding UC, we believe that the available outcomes arising from future studies will clarify the real incidence of CD following COVID19 infection.