Systemic lupus erythematosus (SLE) affects black women more frequently than other racial/gender groups. In past studies, largely consisting of white and Asian cohorts, cigarette smoking was associated with increased SLE risk, and moderate alcohol consumption was associated with decreased SLE risk. The aim of this study was to assess associations of smoking and alcohol consumption with the risk of incident SLE among black women, using data from a long-term, prospective, follow-up study.
The Black Women's Health Study enrolled 59,000 black women in 1995 and collected data on demographics, health status, and medical and lifestyle variables. Follow-up questionnaires that were given every 2 years identified incident disease and updated risk factors. Cases of incident SLE that met the American College of Rheumatology revised criteria for SLE as updated in 1997 were confirmed through medical record review. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI) for associations of cigarette smoking and alcohol intake with incidence of SLE.
A total of 127 incident SLE cases from 1995 to 2015 (mean age 43 years at diagnosis) were confirmed. Compared to never smokers, the risk of SLE among ever smokers was elevated, but not significantly (HR 1.45 [95% CI 0.97-2.18]). Risk was similar for current and past smoking and increased nonsignificantly with increasing pack-years. The HR was 0.71 (95% CI 0.45-1.12) for current drinking relative to never drinking, with a HR of 0.43 (95% CI 0.19-0.96) for ≥4 drinks/week.
Findings from this large study of SLE risk among black women are consistent with previous results from studies in other populations of increased risk of SLE associated with cigarette smoking and decreased risk with moderate alcohol consumption.