Influence of concurrent use of conventional and

Objective: Rheumatoid arthritis (RA) is a chronic autoimmune disease influenced by genetic and environmental factors, including cigarette smoking. However, the impact of e-cigarette use on RA has not been adequately investigated. This study investigated the association between conventional, and e-cigarette use and RA risk in adults aged ≥19 years. Methods: We performed a cross-sectional analysis of data from the Korea National Health and Nutrition Examination Survey (KNHANES) between 2015 and 2021. A total of 21,931 adults aged 19 years and older were categorized into non-smokers, conventional cigarette users, and dual users. RA was defined based on self-reported physician diagnosis. Inverse probability treatment weighting (IPTW)-adjusted logistic regression was employed to estimate adjusted odds ratios (aORs) and 95 % confidence intervals (CIs) for RA. Results: IPTW-adjusted logistic regression demonstrated that dual users had the highest risks of RA (aOR = 1.51, 95 % CI: 1.22, 1.87), while conventional cigarette users also exhibited elevated risks. Conclusions: Dual use of conventional and e-cigarettes is associated with elevated RA risk, even among individuals with lower cumulative smoking exposure. These findings highlight the need for targeted public health strategies addressing dual users and underscore the importance of including e-cigarette use in RA risk assessments.