Causal role of common autoimmune diseases in interstitial cystitis/bladder pain syndrome: Mendelian randomization (MR) study

Observational studies suggest that interstitial cystitis/bladder pain syndrome (IC/BPS) indices might be influenced by autoimmune diseases (AIDs), though it is difficult to infer causal relationships based on observational data due to risk of residual confounding. We utilized Mendelian randomization (MR) to explore causal relevance of multiple AIDs on IC/BPS. Our bidirectional two-sample MR analysis was based on summary statistics from the most recent and comprehensive genome-wide association studies. This particular approach was used to delve into the relationships of cause and effect between IC/BPS and a group of 14 AIDs. We examined a range of AIDs such as ulcerative colitis, Crohn disease, celiac disease, Sjogren syndrome, rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, primary biliary cirrhosis, psoriasis, asthma, eczema, ankylosing spondylitis, type 1 diabetes, and primary sclerosing cholangitis. Our primary analytical approach involved using the inverse variance weighting method to establish causal relationships across various AIDs and IC/BPS conditions. Furthermore, we carried out additional examinations, such as utilizing the weighted median technique, MR-Egger regression, MR-PRESSO, and evaluating reverse causality, in order to strengthen the dependability of our results. Our findings indicate a strong association between genetically predicted asthma and the risk of developing IC/BPS with a weighted odds ratio of 1.692, a confidence interval of 1.147 to 2.496, and P = .008, while the Cochran Q test P = .589 and the MR-Egger intercept test P = .554, MR-PRESSO global test P = .600. No evidence was found for causal relationships between other AIDs and IC/BPS. Individuals with asthma show an increased vulnerability to IC/BPS according to our findings. More randomized controlled trials are necessary to validate these results. These results underscore the importance for healthcare providers to assess the potential risk in asthma patients, offering a novel genetic perspective on studying interstitial cystitis.