Evaluation of Obesity Cutoff Values in Hispanic Adults: Derivation of New Standards

Abstract

The diagnostic accuracy of clinical-based body composition methods such as body mass index (BMI), waist circumference (WC), bioimpedance analysis (BIA), and dual energy X-ray absorptiometry (DXA) has yet to be evaluated in Hispanic adults. Moreover, it has also been suggested that previously established obesity cutoff values may need adjusting.

Purpose: The primary aim of this study was to investigate the diagnostic accuracy of BMI, WC, BIA, and DXA for obesity classification in Hispanic adults. The secondary aim was to internally derive obesity cutoff values producing equal sensitivity and specificity for the respective tests.

Methods: Hispanic females (n = 101) and males (n = 90) volunteered to participate in this study (18-45 years). Body fat percentage was estimated with BIA, DXA, and a 4-compartment (4C) model. Obesity-defined criteria was employed as follows: (Body fat percentage ≥ 25% and 35% and WC ≥ 102cm and 88cm for males and females, respectively; BMI ≥ 30 kg/m²). A 4C model was used as a criterion to evaluate BMI, WC, DXA, and BIA.

Results: Sensitivity of DXA and BIA (74.1%-96.9%) was greater than BMI and WC (25.8%-51.9%) when using previously established standards. However, specificity was poor for DXA (<70%), but considered good to excellent for BMI, WC, and BIA (83.1%-96.6%) when using previously established standards. Internally derived cutoff values improved sensitivity for BMI and WC (74.2%-81.5%) and improved specificity for DXA (>80.0%).

Conclusion: The internally derived cutoff values, producing identical sensitivity, and specificity, were developed and shown to improve the diagnostic performance of the body composition methods compared to previously established obesity cutoff standards. Consequently, the internally derived obesity cutoff values are recommended for use by allied health professionals in clinical practice when equal sensitivity and specificity is desired.

Keywords: Adiposity; bioimpedance analysis; body composition; dual energy X-ray absorptiometry.