Rheumatoid arthritis and airway hyperresponsiveness: A GWAS-based mendelian randomization study

Previous observational studies have indicated a link between rheumatoid arthritis (RA) and airway hyperresponsiveness diseases (AHDs). However, the causality of this relationship remains uncertain. Our research aims to investigate the causal relationship between RA and AHDs. Using publicly available genome-wide association study summary statistics, we selected single nucleotide polymorphisms associated with RA (including overall RA, seropositive RA and seronegative RA), and AHDs (including asthma, bronchitis, allergic rhinitis and chronic obstructive pulmonary disease [COPD]) as instrumental variables for 2-sample Mendelian randomization (MR) analysis. The primary analytical approach was the inverse variance weighted method. Other methods, such as weighted median, weighted mode, MR-Egger regression and MR pleiotropy residual sum and outlier, were employed for quality control. We also used multiple sensitivity analysis methods to verify the robustness of our result. Genetically determined RA (odds ratio [OR] = 1.007, 95% confidence interval [CI] = 1.003-1.011, P < .001), seropositive rheumatoid arthritis (OR = 1.007, 95% CI = 1.002-1.011, P = .037) had a causal effect with asthma, RA (OR = 1.001, 95% CI: 1.000-1.001, P = .022), seropositive rheumatoid arthritis (OR = 1.001, 95% CI: 1.000-1.001, P < .001), or seronegative rheumatoid arthritis (OR = 1.002, 95% CI: 1.001-1.003, P = .001) all were associated with bronchitis risk. No obvious causal relationship was found between RA and allergic rhinitis and COPD. Sensitivity analysis did not find obvious pleiotropy or heterogeneity. The results of this study showed that genetic susceptibility to RA was causally associated with an increased risk of asthma and bronchitis but not with allergic rhinitis and COPD.