Cigarette smoking is associated with an increased risk for systemic lupus erythematosus (SLE) and moderate alcohol consumption is associated with a decreased risk for SLE among black women, according to the results of a study published in Arthritis Care & Research.
Researchers analyzed data from the Black Women’s Health Study, which enrolled 59,000 black women in 1995 and collected data on demographics, health status, and medical and lifestyle variables. Questionnaires sent every 2 years identified changes in health status and updated risk factors. The investigators confirmed diagnoses of SLE through medical record review and used Cox regression models to estimate hazard ratios (HR) for associations of cigarette smoking and alcohol consumption with incidence of SLE.
The investigators identified 127 cases of SLE. These individuals had a mean age of 43 years at diagnosis and 48% were positive for anti-dsDNA or anti-Smith antibodies, 31% had a renal disorder, and 64% had a hematologic disorder. The mean number of American College of Rheumatology criteria was 5.1 among those with SLE.
Multivariate analyses found a nonsignificant increase in the risk of developing SLE (HR, 1.45; 95% CI, 0.97-2.18) for individuals with a history of smoking compared with those who never smoked. Compared with women who never smoked, the risk for SLE associated with current smoking (HR, 1.52; 95% CI, 0.90-2.57) was higher than with past smoking (HR, 1.41; 95% CI, 0.87-2.28), but this association was also not significant.
The multivariate HR associated with <20 pack-years of smoking was 1.37 (95% CI, 0.89-2.11), and the HR associated with ≥20 pack-years of smoking was 1.60 (95% CI, 0.79-3.25). There was no relationship between a history of smoking and the presence of anti-dsDNA or Smith antibodies.
Multivariate HRs for current and past drinking relative to never drinking were 0.71 (95% CI, 0.45-1.12) and 0.78 (95% CI, 0.50-1.25), respectively. For current drinking of ≥4 drinks per week, the multivariate HR was 0.43 (95% CI, 0.19-0.96).
There was an estimated 45% increase in the risk for SLE for ever smoking compared with never smoking for black women, but this finding was of borderline statistical significance. Moderate drinking (≥4 drinks per week) was associated with a 57% reduction in the risk for SLE.
The authors note that these risk associations for black women, who have the highest risk for SLE, are similar to those found in other population groups. They argue that the associations with cigarette smoking and alcohol consumption may point to pathophysiologic mechanisms involved in SLE. Exposure to the toxins in cigarettes is associated with increased oxidative stress and stimulation of autoantibody production, whereas alcohol suppresses pro-inflammatory cytokines. The presence of antioxidants in alcohol such as resveratrol and humulones may influence cytokines and inhibit DNA synthesis.
Cozier YC, Barbhalya M, Castro-Webb N, et al. Relationship of cigarette smoking and alcohol consumption to incidence of systemic lupus erythematosus in the Black Women’s Health Study [published online August 9, 2018]. Arthritis Care Res (Hoboken). doi: 10.1002/acr.23703