Novel Anthropometric Indices: An Allometric Perspective

Background/Objectives: Anthropometric indices based on height (H), weight (W), waist circumference (WC) and hip circumference (HC) can identify incident and future health risks. While BMI provides a standard for relative W (adjusted for H), there is no standard for indices using WC and HC. A body shape index (ABSI) and hip index (HI) have been proposed to extend to respectively WC and HC the same allometric power-law approach used to derive BMI to be independent of H. Here, we compared the mutually independent allometric set H, BMI, ABSI, HI with other proposed indices. Methods: We examined the formulas and rationales of published indices, and used Third National Health and Nutrition Examination Survey (NHANES III) cohort data to investigate their inter-correlations and association with mortality. Results: Many of the proposed indices are based on geometric (isometric) similarity, which does not match human body variability patterns. Unlike ABSI and HI, most proposed indices showed large correlations with BMI, complicating interpretation when considered together with BMI. Indices’ association with mortality risk were generally consistent with their correlations with BMI and ABSI. Combining the separable mortality risks associated with BMI and ABSI, even in a simplified way, outperformed any single index. Conclusions: With calls for incorporating additional indices incorporating WC and HC to supplement BMI in defining obesity, only ABSI and HI are independent of BMI. Additionally, separate risk estimates from these allometric indices can be readily combined to optimize overall risk assessment.