Introduction: Central obesity has been linked more to adverse cardiovascular risks than general obesity. The cut-off values for BMI, waist circumference (WC), waist:hip ratio (WHR), and waist:height ratio (WHtR) have been shown to vary with ethnicity. This study sets out to determine the optimal cut-off values for obesity in adult Nigerians using four anthropometric indices.
Method: In a cross-sectional study of adults in Delta State, Nigeria, data on weight, height, waist circumference, and hip circumference were obtained and BMI, WC, WHR, and WHtR calculated. Using BMI as the standard method for diagnosing obesity, the receiver operating characteristic (ROC) analysis was used to optimise the sensitivity and specificity of the other anthropometric indices.
Results: A total of 866 participants aged 18 years and above were studied, 381 (44.0%) males and 485 (56.0%) females. The prevalence of obesity was 11.2% using a BMI ≥30 kg/m2. On the ROC curve, WHtR had the largest area under curve of 0.862, 0.824 for WC, and 0.655 for WHR. Optimal cut-off values being proposed among adult Nigerians is WHtR ≥0.6, WC > 104 cm, and >90 cm for males and females, and WHR >0.96 and >0.91 for males and females respectively.
Conclusion: WHtR is the best screening tool for diagnosis of abdominal obesity in this setting. Optimal cut-off values for WHtR, WC, and WHR may need upward reviews in this setting compared to existing cut-off values for western populations.