Background/Purpose: Prior case-control studies have reported an inverse association between moderate alcohol consumption and the development of SLE. However, case-control studies may be prone to recall bias and reverse causation. A prior prospective study did not demonstrate an association between alcohol intake and SLE development, although this study was limited by small sample size (34 confirmed cases, Formica MK et al, J Rheum, 2003). We assessed the association between alcohol consumption and risk of SLE among women followed in the Nurses’ Health Study (NHS) and NHSII. We hypothesized that alcohol consumption, possibly through anti-inflammatory effects, would be associated with lower risk for SLE compared to no alcohol consumption. 

Methods: The NHS enrolled 121,701 U.S. female registered nurses in 1976. NHS II began in 1989, enrolling 116,430 female nurses. Lifestyle and environmental exposures were collected through biennial questionnaires. Alcohol consumption was assessed with a semi-quantitative food frequency questionnaire completed every 4 years. Participants in NHS and NHSII who provided alcohol data at baseline (1980 in NHS and 1989 in NHSII) were included. Cumulative average alcohol consumption until 2-4 years prior to SLE diagnosis date (for cases) across repeated measures was used instead of one-time measure to best represent long-term alcohol consumption. The incident SLE cases were identified using the connective tissue disease screening questionnaire (CSQ), followed by medical record review. Cox proportional hazards models were used to assess associations, after controlling for time-varying covariates. HRs from the two cohorts were meta-analyzed using DerSimonian and Laird random effects models. 

Results: 118 incident SLE cases developed in NHS from 1980-2008, and 92 incident SLE cases developed in NHSII, 1991-2009. Mean age at diagnosis was 53.6 (± 8.2) years in NHS and 43.4 (± 5.7) in NHSII. Most SLE cases (97% in NHS, 100% in NHSII) were ANA positive, while 33% of NHS SLE cases and 53% of those in NHSII had a positive anti-dsDNA antibody test at diagnosis. In both NHS and NHSII, there was a suggestion of a protective effect of alcohol intake on risk of SLE, although it was not statistically significant (Table). Meta-analysis of the multivariable-adjusted results from both cohorts demonstrated a suggested protective effect of alcohol consumption in women who consume >0 to 10 gms/day (HR 0.75, 95%CI 0.54, 1.04) and >10 gms/day (HR 0.61,95% CI 0.37, 1.01).

Conclusion: In these large prospective cohorts of women followed for many years before the diagnosis of SLE, we found a potential protective association between long-term alcohol consumption and reduced risk of developing SLE. Further studies are needed to confirm these findings.