P1201 Association between Inflammatory Bowel Disease and Henoch-Schönlein purpura: A Bidirectional Two-Sample Mendelian Randomization Study

Abstract

Abstract Background Henoch-Schönlein purpura (HSP) is a systemic small-vessel vasculitis, and its association with inflammatory bowel disease (IBD) has been the focus of considerable research. Despite numerous studies, it remains uncertain whether and in which direction causal relationships exist between HSP and IBD. To reveal the causal association between HSP and IBD, we conducted a bidirectional two-sample Mendelian randomization analysis using publicly available genome-wide association study (GWAS) summary statistics. Methods We obtained summarized data for IBD, Crohn's disease (CD), ulcerative colitis (UC), and HSP from various GWAS. To estimate causality, we used inverse-variance weighted approaches. Additionally, we conducted several sensitivity analyses. In our causality estimates, we present odds ratios (ORs) and 95% confidence intervals (CIs). Results We found that CD (OR: 1.12, 95% CI: 1.00 to 1. 25, P < 0.05), but not UC (OR: 1.04, 95% CI: 0. 909 to 1.19, P > 0.05), had significant positive causal effects on HSP risk. However, the overall result of the MR study demonstrated that there was no causal link between genetic predisposition to IBD and an increased risk of HSP (OR: 1.10, 95% CI: 0.989 to 1.23, P > 0.05). Regarding the reverse directions, no significant causal associations were discovered. Conclusion It appears that CD and HSP are causally related, which could influence clinical decisions regarding the management of CD in patients diagnosed with HSP. However, neither overall IBD nor UC has a causal effect on HSP.