Objective: To investigate the associations of smoking and alcohol consumption with disease activity and functional status in rheumatoid arthritis (RA).
Methods: We conducted a prospective study consisting of 662 patients with RA who were followed up to 7 years from the Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study. Smoking and alcohol consumption were assessed through yearly questionnaires. The disease activity and functional status were measured annually by the Disease Activity Score examined in 28 commonly affected joints using C-reactive protein (DAS28-CRP3) and the Modified Health Assessment Questionnaire (MHAQ). Linear mixed models were developed to assess the longitudinal effects of smoking and alcohol consumption on DAS28-CRP3 and MHAQ after adjustment for potential confounders. The HLA-DRB1 shared epitope (HLA-SE) by smoking and alcohol interactions were also evaluated in the analysis.
Results: The median followup time of the cohort was 4 years. Current smoking was not associated with DAS28-CRP3 in our study, but was associated with a higher MHAQ than nonsmokers with seropositive RA (p = 0.05). Alcohol consumption showed an approximate J-shaped relationship with MHAQ, with the minima occurring at 5.1-10.0 g/day. Compared to no alcohol use, alcohol consumption of 5.1-10.0 g/day was associated with a significant decrease of MHAQ (p = 0.02). When stratified by HLA-SE, the effect of alcohol consumption appeared to be stronger in HLA-SE-positive RA than HLA-SE-negative RA.
Conclusion: We found that current smoking was associated with a worse functional status, while moderate alcohol consumption was associated with a better functional status in RA. Replications of these findings in other prospective studies are needed.
Keywords: ALCOHOL CONSUMPTION; GENE-ENVIRONMENT INTERACTION; HLA SHARED EPITOPE; MODIFIED HEALTH ASSESSMENT QUESTIONNAIRE; RHEUMATOID ARTHRITIS; SMOKING.