In the United States, systemic lupus erythematosus affects black women more frequently than people of any other race and sex. In past research of risk factors for lupus, which have mainly included white and Asian study participants, cigarette smoking has been linked with increased lupus risk, while moderate alcohol consumption has been linked with decreased risk.
Now, the largest study yet of lupus among black women, co-led by a Boston University School of Public Health researcher, has uncovered findings consistent with these previous studies in other populations.
The study, published in the American College of Rheumatology’s journal Arthritis Care & Research, found the risk of lupus increased the more a woman smoked, while women who drank four or more alcoholic drinks per week saw a 57 percent decrease in lupus risk compared to women who did not drink alcohol.
“The identification of risk factors for lupus is especially important for black women because of their high risk of lupus,” says study co–first author Yvette Cozier, associate professor of epidemiology and a Slone Epidemiology Center faculty member. “Studies of other risk factors are in progress,” she says.
The investigators assessed data from the Black Women’s Health Study, a long-term, prospective follow-up study of 59,000 black women across the United States since 1995. A total of 127 new cases of lupus developed between 1995 and 2015.
The risk for lupus was higher by 45 percent among smokers compared with never-smokers, although this did not reach statistical significance. The risk increased with increasing “pack years” of smoking, calculated by multiplying the number of packs of cigarettes smoked per day by the number of years the person has smoked.
The risk of lupus was lower among women who consumed alcohol, with a statistically significant 57 percent decrease for women who drank four or more alcoholic drinks each week compared with women who never drank. Almost all women in the study drank moderately, defined as fewer than seven drinks per week.
The results of the study were similar to those seen in research with white women from the Nurses’ Health Study, says the study’s other co–first author, Medha Barbhaiya of the Hospital for Special Surgery, in New York City.
Although the mechanisms involved in the links seen in this and other studies are unknown, toxic substances from cigarette smoke have been associated with oxidative stress and autoantibody production, and they can directly damage proteins and DNA, the authors wrote. They also noted alcohol suppresses the synthesis of pro-inflammatory molecules. Furthermore, both cigarette smoking and alcohol intake may cause changes in the expression of genes involved in inflammation and autoimmunity, the authors wrote.
The study’s other coauthors were: Nelsy Castro-Webb, research data analyst in the Slone Epidemiology Center; Carolyn Conte, research coordinator in the Slone Epidemiology Center; Lynn Rosenberg, professor of epidemiology and senior epidemiologist at the Slone Epidemiology Center; and Sara Tedeschi, Cianna Leatherwood, and Karen Costenbader of Brigham and Women’s Hospital.