Obesity and functional impairment: influence of comorbidity, joint pain, and mental health.

To examine the relationship between obesity and functional impairment and the influence of comorbidity, joint pain, and mental health on this association, we used US adult respondents (N = 430,912) to the 2007 Behavioral Risk Factor Surveillance Survey (BRFSS-07). Functional impairment was indicated if a respondent was either (i) limited in any way or in any activities because of physical, mental, or emotional problems, or (ii) had any health problem that required using special equipment such as a cane, wheelchair, special bed, or special telephone. Approximately 62.8% of respondents were overweight or obese and 20.3% were functionally impaired. The unadjusted relationship between obesity and functional impairment revealed a classical J-shaped pattern with odds ratios (95% confidence interval) compared to the normal weight group: 1.63 (1.54-1.73), 1.22 (1.20-1.25), 1.77 (1.73-1.81), 2.43 (2.36-2.51), and 4.12 (3.97-4.27) for underweight, overweight, obesity class I, II, and III, respectively. Although inclusion of different combinations of sociodemographic and medical covariates substantially attenuated the unadjusted association, the collective inclusion of all covariates in a single model did not eliminate the significant J-shaped association resulting in the following corresponding adjusted odds ratios: 1.19 (1.13-1.25), 1.01 (0.99-1.04), 1.23 (1.19-1.27), 1.38 (1.32-1.44), and 1.92 (1.82-2.02). The attenuation was mostly influenced by medical comorbidity. In conclusion, functional impairment is associated with obesity, primarily due to medical comorbidity conditions. The significant residual association highlights the importance of sustainable obesity prevention and treatment at both the individual and public level as functional impairment can create burdens at individual, familial, and societal levels.