Smoking increases the chance of developing rheumatoid arthritis in women who otherwise lack genetic risk factors for the disease, reveals research published ahead of print in the Annals of the Rheumatic Diseases.
Rheumatoid arthritis is a chronic, inflammatory disease in which the patient's immune system attacks the joint linings. It is the most serious and debilitating form of arthritis.
Interaction between genes and environmental factors is considered to be fundamentally important in complex autoimmune diseases, such as rheumatoid arthritis.
The authors base their findings on a comparison of 115 postmenopausal women with the disease and 466 women without.
All the women were taking part in the Iowa Women's Health Study, a long term research project tracking participants' lifestyles, such as smoking, and included the ages at which a woman started and gave up smoking and how many cigarettes she smoked every day.
The results showed that smoking almost doubled the odds of developing rheumatoid arthritis in women who had not inherited the most well established genetic risk factor for the disease, HLA-DRB1 SE.
However, among those women who had inherited the genetic risk factor HLA-DRB1 SE, exposure to tobacco smoke was not associated with an increased risk of the disease.
The authors point out that this research was limited to older white women, so it is not yet clear if other age groups and ethnicities would be similarly affected.