Probable risk factors of rheumatoid arthritis, a case control study

Background and Rheumatoid arthritis (RA) is an autoimmune-inflammatory disease that may lead to joint destruction and disability. The purpose of this study was to evaluate the influence of life style، reproduction، and some external factors on the development of rheumatoid arthritis. This is a case-control study، comprised of 184 cases and 184 controls. Possible etiological factors were collected by questionnaire. All variables were analyzed by T test and X2 (SPSS version 17) and P value <0. 05 was considered significant. Odds Ratio (OR) for possible environmental factors was calculated. There were no difference in age، smoking، asthma or allergy history، trauma، vaccination، parent death before puberty and living in city between RA patients and controls. Divorce was significantly more common in RA (P= 0. 04) and the level of education was inversely associated with RA (P= 0. 03) and OR=1. 69 (CI=1. 12 - 2. 55)، exposure to domestic animals and having more than three children were more common in RA but these differences were not statistically significant. In most of the RA patients، the onset of the disease was winter (P= 0. 02). Divorce and low education levels were associated with RA. Because of higher prevalence of RA in winter، more studies on the association of winter environmental factors and RA are recommended.