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Open Access Research article

Accuracy of body fat percent and adiposity indicators cut off values to detect metabolic risk factors in a sample of Mexican adults

Nayeli Macias1, Amado D Quezada1*, Mario Flores1, Mauro E Valencia2, Edgar Denova-Gutiérrez3, Manuel Quiterio-Trenado4, Katia Gallegos-Carrillo5, Simon Barquera1 and Jorge Salmerón45

Author Affiliations

1 Center of Research in Nutrition and Health, National Institute of Public Health, Cuernavaca, Mexico

2 Biology and Chemical Sciences Department, University of Sonora, Hermosillo, Mexico

3 Center of Medical Sciences Research, Mexico State Autonomous University, Toluca, Mexico

4 Health Services and Epidemiological Investigation Unit. Cuernavaca Morelos, Mexican Institute of Social Security, Cuernavaca, Mexico

5 Population Research Center, National Institute of Public Health, Cuernavaca, Mexico

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BMC Public Health 2014, 14:341  doi:10.1186/1471-2458-14-341

Published: 10 April 2014

Abstract

Background

Although body fat percent (BF%) may be used for screening metabolic risk factors, its accuracy compared to BMI and waist circumference is unknown in a Mexican population. We compared the classification accuracy of BF%, BMI and WC for the detection of metabolic risk factors in a sample of Mexican adults; optimized cutoffs as well as sensitivity and specificity at commonly used BF% and BMI international cutoffs were estimated. We also estimated conditional BF% means at BMI international cutoffs.

Methods

We performed a cross-sectional analysis of data on body composition, anthropometry and metabolic risk factors(high glucose, high triglycerides, low HDL cholesterol and hypertension) from 5,100 Mexican men and women. The association between BMI, WC and BF%was evaluated with linear regression models. The BF%, BMI and WC optimal cutoffs for the detection of metabolic risk factors were selected at the point where sensitivity was closest to specificity. Areas under the ROC Curve (AUC) were compared among classifiers using a non-parametric method.

Results

After adjustment for WC, a 1% increase in BMI was associated with a BF% rise of 0.05 percentage points (p.p.) in men (P < 0.05) and 0.25 p.p. in women (P < 0.001). At BMI = 25.0 predicted BF% was 27.6 ± 0.16 (mean ± SE) in men and 41.2 ± 0.07 in women. Estimated BF% cutoffs for detection of metabolic risk factors were close to 30.0 in men and close to 44.0 in women. In men WC had higher AUC than BF% for the classification of all conditions whereas BMI had higher AUC than BF% for the classification of high triglycerides and hypertension. In womenBMI and WC had higher AUC than BF% for the classification of all metabolic risk factors.

Conclusions

BMI and WC were more accurate than BF% for classifying the studied metabolic disorders. International BF% cutoffs had very low specificity and thus produced a high rate of false positives in both sexes.