Pyoderma Gangrenosum in Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

Background Pyoderma gangrenosum (PG) is an uncommon but severe extra-intestinal manifestation (EIM) of inflammatory bowel disease (IBD). The incidence and risk factors for PG are disputed. Aims To assess the incidence of PG and identify factors associated with PG in IBD patients. Methods A search of electronic databases (Ovid and PubMed) was conducted between 1966 and 2019. Studies that calculated the incidence of PG in IBD patient cohorts were included. Patient demographics, IBD subtype, and EIM presence were recorded. A review of our institutional database of 1057 IBD patients was conducted. A multivariate regression model and meta-analysis were conducted to identify risk factors for PG. A random effects model was used to combine the data of included studies. Results Fourteen studies were included in addition to 1057 IBD patients and 26 PG cases from the Louisville cohort. In total, there were 379 cases of PG in the cumulative cohort of 61,695 IBD patients. The PG incidence in individual studies ranged from 0.4 to 2.6%. In the institutional cohort, ocular EIMs and a permanent stoma were significant risk factors for PG. In the meta-analysis, PG was associated with female gender (RR = 1.328, 95% CI 1.161-1.520), Crohn's disease (RR = 1.193, 95% CI 1.001-1.422), erythema nodosum (RR = 9.281, 95% CI 6.081-14.164), and ocular EIM (RR = 4.55, 95% CI 3.04-6.81). There was study heterogeneity when assessing IBD subtype, ocular, and joint EIMs. Conclusions There are conflicting data on the incidence and risk factors for PG. This meta-analysis confirms an association between PG and female gender, Crohn's disease, erythema nodosum, and ocular EIM that have been described in smaller studies.