Research indicates that smoking is a major preventable rheumatoid arthritis risk factor and accounts for over a 3rd of the most common and severe kind of rheumatoid arthritis cases.
Smoking also accounts for over 50% of cases in individuals who have a genetic susceptibility to rheumatoid arthritis.
The results are based on 871 of rheumatoid arthritis free people and over 1,200 individuals having rheumatoid arthritis, all matched for sex and age, and all between the ages of 18 to 70. They were all quizzed regarding their smoking habits and then grouped into 3 categories based on how long they had smoked.
Blood samples were obtained to assess the genetic profile of all individuals for rheumatoid arthritis susceptibility and to gauge their disease severity, as indicated by their levels of antibodies.
61% of individuals having rheumatoid arthritis had the most severe and common kind of rheumatoid arthritis, as determined by a positive test for anticitrullinated protein/peptide antibody.
The heaviest smokers, individuals smoking 20 cigarettes each day for 20 years or more, were 2.5 x as likely or more to test anticitrullinated protein/peptide antibody positive. The longer ex-smokers had quit smoking, the more the risk decreased. But there was still a relatively high risk among the heaviest ex-smokers, despite having not smoked for 20 years.
It was then determined from these figures that smoking accounted for 35% positive anticitrullinated protein/peptide antibody cases, and 1 in 5 rheumatoid arthritis cases.
This risk is similar to that for coronary artery heart disease, even though it isn’t as high compared to lung cancer, where smoking accounts for 90% of cases,.
In individuals who are genetically susceptible to rheumatoid arthritis, and who tested positive for anticitrullinated protein/peptide antibody, smoking accounted for 55% of the cases, and the highest risk for individuals who smoked the most.
The researchers mention that a number of other environmental factors could contribute to an increased rheumatoid arthritis risk, which includes hormonal factors and air pollutants. They however suggest that the study results are sufficient enough to advise individuals with a family history of rheumatoid arthritis to quit smoking.