Estimations claim that 1.3 million Americans are diagnosed with Rheumatoid arthritis (RA) and 75 percent of them are women. A latest study suggests that African Americans smoking cigarettes have an increased risk of developing RA. The threat seems to be especially greater among people positive for the HLA-DRB1 shared epitope. It is known that the HLA-DRB1 shared epitope is a genetic risk factor for RA.
The study included 605 RA patients and 255 healthy controls from the Consortium for the Longitudinal Evaluations of African Americans with Early Rheumatoid Arthritis (CLEAR) I study group. It was mentioned that RA patients had less than two year disease duration from the time of symptom onset. The CLEAR II study group consisted of RA patients with any disease duration. Scientists kept a tab on smoking status whether it is current, former or never. Also cumulative smoking exposure and genetic risk factor HLA-DRB1 shared epitope (SE) was taking into consideration.
“RA epidemiology has been largely understudied in the African American population. The aim of our study was to bridge the knowledge gap by determining whether smoking contributes to RA risk in African Americans and define the extent to which this association is affected by genetic risk,” alleged Dr. Ted Mikuls, MD, MSPH, from the University of Nebraska Medical Center and lead study author.
The study findings reveal that RA patients are a little more likely to be former or current smokers and very few of them have never smoked. 54 percent RA patients and 35 percent controls were heavy smokers. Presumably 40 percent RA patients and 23 percent controls had at least one HLA-DRB1 SE-containing allele. A two-fold increase in RA risk appeared among African Americans who were heavy smokers. The threat was supposedly more than four-fold in the presence of SE alleles. Scientists believe that smoking cessation or by limiting cumulative smoking exposure to less than 10 pack-years can help avoid RA cases in African Americans.
The study will be published in the December issue of Arthritis and Rheumatism.