The Association Between Body Mass Index and Arthritis Among US Adults: CDC’s Surveillance Case Definition

INTRODUCTION The Centers for Disease Control and Prevention modified the surveillance case definition of arthritis to a more stringent form in 2002. To date, the association between arthritis and obesity (an established risk factor for arthritis) has not been examined with the new definition. We describe the association between body mass index (BMI) (kg/m(2)) and arthritis using the new arthritis case definition to provide a more accurate assessment of the relationship between weight and arthritis among US adults. METHODS We used data from the 2005 Behavioral Risk Factor Surveillance System (N = 356,112) and univariate and multivariate analyses to assess the relationship between BMI and arthritis among US adults. RESULTS Overall, 26% of US adults had self-reported arthritis. Obese respondents (BMI >or=30.0 kg/m(2)) were 1.9 times more likely to report arthritis compared with normal-weight respondents (BMI <25.0 kg/m(2)), and distinguishing between obese levels revealed an even greater association between BMI and arthritis (class III obesity [BMI >or=40.0], odds ratio [OR] = 3.3, 95% confidence interval [CI] = 3.1-3.6; class II obesity [BMI 35.0-39.9 kg/m2], OR = 2.5, 95% CI = 2.3-2.7; class I obesity [BMI 30.0-34.9], OR = 1.9, 95% CI = 1.8-2.0). CONCLUSION BMI is an independent risk factor for self-reported arthritis. Maintaining a healthy weight may delay the onset of arthritis. More research is needed to determine the effect of weight loss on the progression of arthritis in overweight individuals.