MONDAY, Nov. 29 (HealthDay News) -- Cigarette smoking appears to be significantly associated with autoantibody positive and negative rheumatoid arthritis (RA) in African-Americans with more than 10 pack-years of exposure, according to a study published online Aug. 18 in Arthritis & Rheumatism.
Ted R. Mikuls, M.D., of the University of Nebraska Medical Center in Omaha, and colleagues measured smoking status and cumulative smoking exposure and determined HLA-DRB1 shared epitope (SE) status in 605 African-American patients with RA and in 255 healthy controls.
After adjusting for age and gender, the investigators found that ever (odds ratio, 1.45) and current smoking (odds ratio, 1.56) were more common in African-American RA patients compared with healthy controls. The association of smoking with RA was limited to those with a cumulative exposure exceeding 10 pack-years, which was evident in both autoantibody positive and negative disease. The investigators also found evidence of a significant additive interaction between SE status and heavy smoking but there was no evidence of multiplicative interactions.
"In summary, cigarette smoking is significantly associated with RA in African-Americans, an association that is most pronounced with a cumulative smoking history exceeding 10 pack-years. Similar to reports involving populations of European ancestry, the risk attributed to smoking is highest in African-Americans positive for HLA-DRB1 SE alleles with evidence of a significant biologic interaction between SE and heavy smoking in RA risk," the authors write.
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