Objectives: The aim of the present study is to determine the association between risk of rheumatoid arthritis (RA) and alcohol consumption in combination with smoking and HLA-DRB1 shared epitope (SE).
Methods: Data from two independent case-control studies of RA, the Swedish EIRA (1204 cases and 871 controls) and the Danish CACORA- (444 cases and 533 controls) were used to estimate odds ratios (OR) of developing RA for different amounts of alcohol consumed.
Results: Alcohol consumption was, more common in controls (p<0.05) and dose-dependently associated with reduced risk of RA (p-trend<0.001) in both studies. Among alcohol consumers, the quarter with highest consumption had a decreased risk of RA in the order of 40-50% compared with the half with the lowest consumption EIRA: (OR=0.5 (95% confidence interval (CI) 0.4-0.6) and CACORA: OR=0.6 (95% CI 0.4-0.9)). For the subset of RA that is seropositive for antibodies to citrullinated peptide antigens, alcohol consumption was observed to reduce the risk the most in smokers carrying HLA-DRB1 SE alleles.
Conclusions: The observed inverse association between alcohol intake and risk of RA and the recent demonstration of a preventive effect of alcohol in experimental arthritis, indicates that alcohol may protect against RA. This highlights the potential role of life-style in determining the risk to develop RA, and emphasises the advice to stop smoking, but not necessarily to abstain from alcohol in order to diminish risk of RA. More generally, the evidence of potential RA prevention, urges for additional studies on how this can be achieved.