Association Between Chronic Obstructive Pulmonary Disease and Rheumatoid Arthritis: Findings of the Observational and Mendelian Randomization Study

Background: Airway inflammation is considered one of the pathogenic factors in rheumatoid arthritis (RA), but the role of chronic obstructive pulmonary disease (COPD) in the development of RA remains unclear. We used cross-sectional studies and Mendelian randomization (MR) analysis to explore the link between COPD and RA. Methods: In National Health and Nutrition Examination Survey (NHANES) 2013-2018, the association between COPD and RA was investigated using weighted logistic regression models. We also used subgroup analysis and interaction tests to explore the relationship between COPD and RA in populations with different clinical characteristics. The inverse-variance weighted (IVW) method was the primary method of MR analysis for investigating the causal effect of exposure on outcome. Results: After adjusting for smoking history and other variables, weighted logistic regression analysis of 14768 participants indicated that COPD is associated with an increased odds of developing RA (OR = 1.899, p < 0.001). Interaction tests showed that there is an interaction with this relationship concerning gender, age, body mass index (BMI), and hypercholesterolemia (p < 0.05). MR analysis showed a causal relationship between COPD and increased odds of RA (OR = 1.072, p = 0.008). Multivariable MR analysis, adjusted for smoking, also yielded the same result (OR = 1.071, p = 0.024). Conclusion: Our study suggests that COPD may have a potential causal role in the development of RA. Further research is needed to validate our findings.