Obesity, Physical Inactivity Linked to Arthritis Risk in Women
By Brande Nicole Martin
Medscape Medical News
February 26, 2010 — Obesity and physical inactivity, particularly in women, may account for the high prevalence of arthritis and arthritis-attributable activity limitations (AAL) in the United States compared with Canada, according to a cross-sectional study.
The study, led by Elena Badley, DPhil, from Toronto Western Research Institute and University of Ontario, Canada, is published in the March issue of Arthritis Care Research.
This is the first study to directly compare health disparities associated with the prevalence and risk factors for arthritis and AAL between the 2 countries. The study also evaluated how obesity and leisure-time physical inactivity affected arthritis and AAL.
"The major strength of the study was the comparability in the methodology of the study between the two countries," write Dr. Badley and coauthor Hina Ansari, MSc, from Toronto Western Research Institute.
The study used data from the 2002 to 2003 Joint Canada/United States Survey of Health. It was a 1-time, random, computer-assisted telephone survey targeting adults aged 18 years or older in noninstitutionalized households in the 50 US states and all 10 Canadian provinces. Those living in healthcare institutions, nursing homes, full-time members of the US and Canadian Armed Forces, and residents of the 3 Canadian territories were excluded from the study.
Overall, 3505 Canadians (65%) and 5138 Americans (50.2%) responded to the Joint Canada/United States Survey of Health.
Study Variables Assessed
Survey participants were asked a series of questions related to diagnosis of arthritis, difficulty level when performing in various activities, sociodemographic data, lifestyle factors, and access to healthcare. The main study variables were arthritis prevalence, AAL, body mass index, and physical inactivity. More than 95% of participants responded to questions about these variables.
In the United States, the estimated prevalence of arthritis was higher (18.7%; 95% confidence interval [CI], 17.6 - 19.8) than in Canada (16.8%; 95% CI, 15.5 - 18.2). For AAL, the estimated prevalence was also higher in the United States (9.6%; 95% CI, 8.8 - 10.5) vs Canada (7.7%; 95% CI, 6.8 - 8.6).
Further, the study authors found that US women had a higher prevalence of arthritis compared with Canadian women: 23.3% (95% CI, 21.7 - 25.0) vs 19.6% (95% CI, 17.7 - 21.5), respectively. The prevalence of AAL was 13.0% (95% CI, 11.7 - 14.3) and 9.2% (95% CI, 7.9 - 10.6) for US and Canadian women, respectively.
Men in both countries had similar prevalence of arthritis and AAL (about 14% and 6%, respectively). In addition, overall, both women and men with arthritis also reported AAL (44.7% of Americans and 39.3% of Canadians). In both countries, those who were physically inactive were more likely to have arthritis and AAL.
Several of the study limitations were common to using secondary databases. Other limitations include differences in data reporting between the 2 countries, exclusion of racial variables and insurance coverage data, varying ways in defining and distinguishing between types of "arthritis" and categorizing body mass index groups, and inclusion of leisure time activities only (work- or home-related activities were not necessarily accounted for).
Arthritis as Part of Public Health Message
"Our study results suggest that higher prevalence of arthritis and AAL in the US may be a consequence of greater obesity and physical inactivity in that country, particularly in women," Dr. Badley said in a news release.
Dr. Badley stresses that public health initiatives "that promote healthy weight and physical activity" should include arthritis in the health prevention messages to potentially reduce the incidence of arthritis and AAL.
The study was supported by the Ontario Ministry of Health and Long Term Care through its Health System-Linked Research Unit grant scheme. The study authors have disclosed no relevant financial relationships.
