To evaluate the association of alcohol consumption with the risk of rheumatoid arthritis (RA) in 2 large prospective cohorts, the Nurses' Health Study (NHS) and NHSII.
The NHS was established in 1976 and enrolled 121,701 female registered nurses in the US. The NHSII began in 1989, enrolling 116,430 female nurses. Lifestyle and environmental exposures were collected through biennial questionnaires. Alcohol consumption was assessed with a food frequency questionnaire, which was completed every 4 years. Incident RA cases were identified using a connective tissue disease screening questionnaire and a medical record review. Separate Cox proportional hazards models were used to estimate hazard ratios (HRs) after adjusting for potential confounders in the NHS and NHSII. The pooled HR from 2 cohorts was estimated using a DerSimonian and Laird random-effects model.
Among 1.90 million person-years from 1980 to 2008, 580 incident cases of RA were diagnosed in the NHS cohort, and among 1.78 million person-years from 1989 to 2009, 323 incident cases of RA were diagnosed in the NHSII cohort. Compared to no use, the pooled multivariable adjusted HR for alcohol use of 5.0-9.9 gm/day was 0.78 (95% confidence interval [95% CI] 0.61-1.00). For seropositive RA cases, the association appeared stronger (HR 0.69 [95% CI 0.50-0.95]). In addition, women who drank beer 2-4 times a week had a 31% decreased risk compared to women who never drank beer.
We found a modest association between long-term moderate alcohol drinking and reduced risk of RA. Future studies are needed to confirm our findings in other populations.