Rheumatoid arthritis is an autoimmune disease, which causes chronic inflammation of the joints. The cause of the disease is unknown, but interaction between genes and environmental factors is thought to trigger the immune system to attack the body's own tissues resulting in inflammation of the joints. It is a progressive illness that has the potential to cause joint destruction and functional disability.
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.