Comparison of the performance of two measures of central adiposity among apparently healthy Nigerians using the receiver operating characteristic analysis

OBJECTIVE: To compare the performance of waist circumference (WC) and waist-to-hip ratio (WHR) in predicting the presence of cardiovascular risk factors (hypertension and generalized obesity) in an apparently healthy population. MATERIALS AND METHODS: We recruited 898 apparently healthy subjects (318 males and 580 females) of the Igbo ethnic group resident in Enugu (urban), Southeast Nigeria. Data collection was done using the World Health Organization Stepwise approach to Surveillance of risk factors (STEPS) instrument. Subjects had their weight, height, waist and hip circumferences, systolic and diastolic blood pressures measured according to the guidelines in the step 2 of STEPS instrument. Generalized obesity and hypertension were defined using body mass index (BMI) and JNC 7 classifications, respectively. Quantitative and qualitative variables were analyzed using t-test and Chi-square analysis, respectively, while the performance of WC and WHR was compared using the Receiver Operating Characteristic (ROC) analysis. P value was set at <0.05. RESULTS: The mean age of the subjects was 48.7 (12.9) years. Central obesity was found in 76.9% and 66.5% of subjects using WHR and WC, respectively. WC had a significantly higher area under the curve (AUC) than WHR in all the cardiovascular risk groups, namely, generalized obesity (AUC = 0.88 vs. 0.62), hypertension alone (AUC = 0.60 vs. 0.53), and both generalized obesity and hypertension (AUC = 0.86 vs. 0.57). CONCLUSION: WC performed better than WHR in predicting the presence of cardiovascular risk factors. Being a simple index, it can easily be measured in routine clinic settings without the need for calculations or use of cumbersome techniques.