Role of disability in the association between obesity and unintentional injuries

We assessed the mediating role of disability in the association between obesity and elevated injury risk among U.S. white and African American adults.

Data from the 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) were analyzed. Respondents were categorized into 6 groups: underweight (<18.5 kg/m(2)), normal weight (18.5-24.9 kg/m(2)), overweight (25.0-29.9 kg/m(2)), obese class I (30.0-34.9 kg/m(2)), obese class II (35.0-39.9 kg/m(2)), and obese class III (≥40 kg/m(2)). Responses to the 12 items in SF-12v2 were used to transform raw scales to the norm-based Physical Component Summary measure (PCS). Disability was defined as having a PCS score below 30 (mean, -2.00 SD). Self-reported unintentional injuries in the past 12 months were compared between respondents with and without disability within each body mass index (BMI) category. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were examined for men and women separately using 3 logistic regression models that considered age, race, education level, poverty status, chronic medical conditions, major injury risk behaviors, obesity, and disability status.

A total of 31,276 non-Hispanic white and African American respondents reported an injury incidence of 18.6%. Disability correlated with significantly higher injury incidence (p < .01). Controlling for major sociodemographics, chronic medical conditions, and major injury risk behaviors, we observed a statistically significant association between obesity and injuries (OR = 1.27, 95% CI = 1.06-1.54, for BMI ≥ 40; OR = 1.11, 95% CI = 1.01-1.23, for BMI of 30.0 to <40) among women; however, this association became nonsignificant after status of disability was considered in the final regression model. This finding was not seen for men.

The elevated injury risk among white and African American women with extreme obesity was mediated substantially by disability. No such finding was found, however, for men.