Abstract

Objective: Several studies have suggested that alcohol drinking is protective for the development and progression of systemic lupus erythematosus (SLE). However, a protopathic bias might also explain this apparent association. Our objective was to investigate the association between alcohol consumption and incidence of SLE in a data set that has information on both current and pre-diagnostic alcohol consumption.

Methods: We performed an Internet-based case–control study of SLE. Cases were diagnosed within 5 years of the study and met ⩾4 American College of Rheumatology criteria for SLE. The control participants were tightly matched to cases on demographic and socio-economic characteristics using a propensity score. Participants completed an online exposure assessment. We used conditional logistic regression analyses to test the association of current and pre-diagnostic alcohol consumption with SLE.

Results: The sample comprised 114 cases with SLE and 228 matched controls. Current drinking (>2 days per week) was inversely associated with SLE (OR 0.35, 95% CI 0.13 to 0.98). Having more than two drinks per day was also inversely associated with SLE (OR 0.41, 95% CI 0.18 to 0.93). However, alcohol consumption before SLE diagnosis was not associated with the risk of SLE (p⩾0.4). Analysis of the change in drinking habits showed that people with lupus were more likely to quit drinking before (OR 2.25, 95% CI 0.96 to 5.28) or after (OR 2.38, 95% CI 0.88 to 6.49) being given the SLE diagnosis.

Conclusions: Our results show that alcohol consumption before SLE diagnosis is not associated with the risk for SLE, and that individuals who develop SLE are more likely to quit.