Electronic cigarette use and risk of incident rheumatoid arthritis and systemic lupus erythematosus in the all of us research program.

BACKGROUND: Electronic cigarettes (e-cigarettes) are increasingly used as a substitute or in addition to cigarettes. Although cigarette smoking is a well-established risk factor for both rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), the association between e-cigarette use and the development of RA or SLE remains unclear. We investigated e-cigarette use and the risk of incident RA or SLE. METHODS: Using All of Us Research Program (version 8) data, e-cigarette current users were matched by age, sex, race/ethnicity, enrollment year, and cigarette smoking status to non-users, and followed from enrollment until 1st occurrence of RA or SLE, death, end of study period (October 1, 2023), or up to 5 years, whichever first. We estimated incidence rates (IR) and incidence rate ratios (IRR), and calculated hazard ratios (HRs) using Cox models adjusting for other potential confounders. We also performed smoking- and disease state-stratified analyses. RESULTS: We identified 15,909 e-cigarette current users and matched non-users. A total of 66 cases of RA or SLE developed among current e-cigarette users in 46,038 person-years vs (IR 1.43/1000 person-years) vs. 43 incident cases among matched non-users in 46,203 person-years (IR 0.93/1000 person-years; IRR 1.54, 95% CI 1.05-2.26; adjusted HR 1.49; 95% CI 1.01-2.20). In stratified analyses, risks were higher among e-cigarette users than non-users who were past or current smokers, and elevated for both RA and SLE, although with smaller sample sizes. CONCLUSIONS: Current e-cigarette use was associated with an increased risk of RA or SLE. Further studies are needed to evaluate dose-response relationships.