Previous studies, have shown a dose-dependent inverse association with alcohol consumption and rheumatoid arthritis (RA), whereas smoking is an established risk factor for RA. A team of researchers explored the association between alcohol consumption and RA incidence and investigated a potential interaction between alcohol and smoking habits, regarding RA incidence.
The prospective cohort study was based on 41 068 participants with detailed assessment of alcohol intake, smoking and potential confounders at baseline in 1997. 577 incident cases of RA were identified during a mean of 17.7 years of follow-up. Multivariate Cox proportional hazards models were used to estimate HR with 95% CI. Interaction on the additive scale between alcohol and smoking was also estimated by calculating the attributable proportion due to interaction (AP).
Overall, alcohol consumption was associated with a 30% reduced incidence of RA (HR 0.69, 95% CI 0.55 to 0.86) with a dose–response relationship which remained significant after stratification by age and smoking habits. The positive association between smoking and RA incidence was reduced with increasing alcohol consumption A synergistic effect was observed between alcohol and smoking (AP 0.40, 95% CI 0.15 to 0.64), indicating that 40% of the cases among the double exposed are due to the interaction per se.
Our findings suggest an inverse association between alcohol consumption and rheumatoid arthritis incidence, and a synergistic effect between alcohol and smoking.
Source: Hedenstierna L, Bellocco R, Ye W, et al. Effects of alcohol consumption and smoking on risk for RA: results from a Swedish prospective cohort study. RMD Open 2021;7:e001379.