To compare directly the prevalence and risk factors for arthritis and arthritis-attributable activity limitations (AAL) between the US and Canada, and to estimate the population attributable risk percentage (PAR%) for obesity and leisure time physical inactivity.
We conducted analyses of the 2002-2003 Joint Canada/US Health Survey, which asked about health professional-diagnosed arthritis, and arthritis reported as a cause of disability in specified activities of daily living. We used log-Poisson regression to obtain prevalence ratios for arthritis and AAL, adjusting for education, income, having a regular doctor, physical inactivity, and obesity. PAR% for obesity and physical inactivity were calculated.
The estimated crude prevalence of arthritis and AAL were 18.7% and 9.3%, respectively, in the US and 16.9% and 7.4%, respectively, in Canada. Being American was a significant bivariate predictor of arthritis and AAL, but not after adjustment for obesity and physical inactivity. PAR% for obesity were 14% and 20% for arthritis and AAL, respectively, for Americans and 13% and 17%, respectively, for Canadians, and for physical inactivity were 15% and 21%, respectively, for Americans and 4% and 5%, respectively, for Canadians, with estimates being higher among women.
The higher prevalence of arthritis and AAL in the US may be accounted for by the higher prevalence of obesity and physical inactivity, particularly in women. The high PAR% related to obesity in both countries, and physical inactivity in the US, point to the importance of public health initiatives to reduce obesity and increase physical activity to reduce the prevalence of arthritis and AAL.