Objective: To analyse the association between alcohol intake and incidence of rheumatoid arthritis in women.
Design: Prospective cohort study with repeated measurements.
Setting: The Swedish Mammography Cohort, a population based cohort from central Sweden.
Participants: 34,141 women born between 1914 and 1948, followed up from 1 January 2003 to 31 December 2009.
Main outcome measures: Newly diagnosed cases of rheumatoid arthritis identified by linkage with two Swedish national registers. Data on alcohol consumption were collected in 1987 and 1997.
Results: During the follow-up period (226,032 person years), 197 incident cases of rheumatoid arthritis were identified. There was a statistically significant 37% decrease in risk of rheumatoid arthritis among women who drank >4 glasses of alcohol (1 glass = 15 g of ethanol) per week compared with women who drank <1 glass per week or who never drank alcohol (relative risk 0.63 (95% confidence interval 0.42 to 0.96), P = 0.04). Drinking of all types of alcohol (beer, wine, and liquor) was non-significantly inversely associated with the risk of rheumatoid arthritis. Analysis of long term alcohol consumption showed that women who reported drinking >3 glasses of alcohol per week in both 1987 and 1997 had a 52% decreased risk of rheumatoid arthritis compared with those who never drank (relative risk 0.48 (0.24 to 0.98)).
Conclusion: Moderate consumption of alcohol is associated with reduced risk of rheumatoid arthritis.