The causal relationship between rheumatoid arthritis and interstitial lung disease in East Asian population: A two-sample Mendelian randomization study

To investigate the causal relationship between rheumatoid arthritis (RA) and interstitial lung disease (ILD) in the East Asian population, we utilized Mendelian randomization (MR). Publicly available summarized data from genome-wide association studies on RA (4199 cases and 208,254 controls), and the data on ILD (1046 cases and 176,974 controls) were obtained from BioBank Japan. Eligible single nucleotide polymorphisms from East Asian populations were obtained from genome-wide association studies as instrumental variables, and 11 RA-related single nucleotide polymorphisms (P < 5 × 10-8) were selected as instrumental variables. MR analysis was performed using inverse variance weighted, MR-Egger regression, weighted median, and MR-PRESSO with RA as the exposure data and ILD as the outcome data. Reliability was evaluated using Cochran Q test, MR-Egger intercept, leave-one-out analysis, and funnel plot. Inverse variance weighted results showed an odds ratio (95% confidence interval) of 1.29 (1.18-1.41), P = 3.99 × 10-8, indicating a positive association between RA and ILD. The reliability evaluation could adopt the fixed-effect model, and the absolute value of the MR-Egger regression intercept was 0.021, P > 0.05, and P value of Global Test in MR-PRESSO was 0.573. The test results of the leave-one-out showed that the results are robust, and the funnel plot indicated that the instrumental variables were not affected by potential factors. In conclusion, this study demonstrates that RA is a risk factor for ILD in the East Asian population.