Implementation of permutation testing to determine clustering of social and behavioral risk factors for coronary heart disease, National Health and Nutrition Examination Survey 2001–2004

PurposeTo determine whether social and behavioral risk factors for coronary heart disease, including education, physical activity, fruit/vegetable intake, and smoking, cluster (i.e., co-occur more than expected as the result of chance) in U.S. adults.MethodsThe study included 4305 male and 4673 female subjects aged ≥20 years from the National Health and Nutrition Examination Survey. Risk factors included: ≤high school diploma/general educational development certificate; <150 minutes of moderate/vigorous physical activity per week; <3 or <2 servings of vegetables and fruit, respectively, per day; and smoking cigarettes. Indicator variables were summed into a sociobehavioral risk index (SRI, range 0 [no risk factors] to 4 [all risk factors]). Ratios of observed-to-expected prevalence (under the assumption of independence) of the SRI were assessed. Statistical significance was evaluated by the use of randomly permuted average observed-to-expected SRI ratios and 95% confidence intervals (95% CIs).ResultsIn male subjects, the ratio of observed-to-expected prevalence of SRI = 0 was 1.70 (permuted ratio = 1.00; 95% CI: 0.92–1.08), and SRI = 4 was 2.10 (permuted ratio = 1.00, 95% CI: 0.86–1.14), demonstrating significant clustering. In females, the ratio of observed-to-expected prevalence of SRI = 0 was 1.67 (permuted ratio = 1.00, 95% CI: 0.92–1.08), and SRI = 4 was 1.86 (permuted ratio = 1.00, 95% CI: 0.85–1.15).ConclusionsSocial and behavioral risk factors for coronary heart disease cluster in this sample of U.S. adults.