BMI is dead; long live waist-circumference indices: But which index should we choose to predict cardio-metabolic risk?

Background and aims: There is growing evidence that Body Mass Index (BMI) is unfit for purpose. Waist circumference (WC) indices appear to be the preferred alternative, although it is not clear which WC index is optimal at predicting cardio-metabolic risk (CMR) and associated health outcomes. Methods and results: We obtained a stratified random probability sample of 53,390 participants from the Health Survey for England (HSE), 2008-2018. The four available CMR factors were; high-density lipoproteins (HDL) cholesterol, glycated haemoglobin (HbA1c), systolic (SBP) and diastolic blood pressure (DBP). Strength of association between the four cardio-metabolic risk factors and competing anthropometric indicators of weight status [BMI, Waist-to-height ratio (WHTR), unadjusted WC, and a new WC index independent of height, WHT.5R = WC/height(0.5)] was assessed separately, using simple correlations and ANCOVAs, and together (combined) using MANCOVA, controlling for age, sex and ethnicity. Centile curves for the new index WHT.5R = WC/height(0.5) were also provided. Conclusions: Waist-circumference indices were superior to BMI when explaining/predicting our CMR factors, before and after controlling for age, sex and ethnicity. No single WC index was consistently superior. Results suggest that WHTR is the strongest predictor of HbA1c, confirming that shorter individuals are at great risk of diabetes. The most appropriate WC index associated with blood pressure was WHT.5R for DBP, or unadjusted WC for SBP. Given HDL cholesterol is independent of height, the best predictor of HDL was WHT.5R. Clearly, no one size fits all!. MANCOVA identified WHT.5R to be the best single WC index associated with a composite of all four CMR factors. (C) 2022 The Author(s). Published by Elsevier B.V. on behalf of The Italian Diabetes Society, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University.

Automated summary

The study found that Body Mass Index (BMI) is insufficient for accurately measuring weight status. Waist circumference (WC) indices are considered to be better alternatives, but it is unclear which WC index is most effective at predicting cardio-metabolic risk (CMR) and associated health outcomes. The analysis of the data revealed that WC indices outperformed BMI in explaining and predicting CMR factors, particularly waist-to-height ratio (WHTR) for predicting the risk of diabetes.