Background Only one study has evaluated the association between exercise and risk of developing RA, showing no association .
Objectives To examine the association between physical activity and risk of developing rheumatoid arthritis (RA) in middle age and elderly women from the Swedish Mammography Cohort, a population-based prospective study .
Methods Data on physical activity were collected in 1997 by self-administrated food-frequency questionnaire (FFQ). Risk of RA associated with physical activity was estimated using Cox proportional hazard regression models.
Results Among 30,112 women born between 1914 and 1948 followed-up from January 1, 2003 to December 31, 2010, 201 RA cases were identified (226,477 person-years). There was a statistically significant 35% lower risk of RA (relative risk (RR), 0.65; 95% confidence interval (CI), 0.43-0.96) among women in the highest category of leisure-time activity (combining more than 20 minute per day of walking/bicycling (median 40-60 minute per day) and more than 1 hour per week of exercise (median 2-3 hours per week)) as compared to women in the lowest category (less than 20 minute per day of walking/bicycling and less than 1 hour per week of exercise). A non-statistically significant decreased risk was observed for household work (-32%) and work/occupation (-15%), while an increased risk was observed for leisure-time physical inactivity (+27%). Daily energy expenditure was not associated with risk of RA.
Conclusions This prospective population-based cohort study of women supports the hypothesis that physical activity can be a protective factor in the etiology of rheumatoid arthritis. Our results add to accumulated evidence on benefits of modifiable leisure-time physical activity for prevention of many other chronic diseases.
Cerhan JR, Saag KG, Criswell LA, Merlino LA, Mikuls TR: Blood transfusion, alcohol use, and anthropometric risk factors for rheumatoid arthritis in older women. J Rheumatol 29(2), 246-254 (2002).
Harris H, Håkansson N, Olofsson C, Julin B, Åkesson A, Wolk A. The Swedish mammography cohort and the cohort of Swedish men: Study design and characteristics of 2 population-based longitudinal cohorts. OA Epidemiology 2013 Oct 01;1(2):16.
Disclosure of Interest None declared
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