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

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.

SUBMITTER: Macias N

PROVIDER: S-EPMC4108012 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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

Macias Nayeli N Quezada Amado D AD Flores Mario M Valencia Mauro E ME Denova-Gutiérrez Edgar E Quiterio-Trenado Manuel M Gallegos-Carrillo Katia K Barquera Simon S Salmerón Jorge J

BMC public health 20140410

<h4>Background</h4>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 inter ...[more]

PMID: 24721260

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Project description:Background & aimsThe quality of dietary carbohydrates rather than total carbohydrate intake may determine the accumulation of visceral fat; however, to date, few studies have examined the impact of diet on adiposity using specific imaging techniques. Thus, the aim of this prospective study was to investigate the association between concurrent changes in carbohydrate quality index (CQI) and objectively-quantified adiposity distribution over a year.MethodsWe analyzed a cohort of 1476 participants aged 55-75 years with overweight/obesity and metabolic syndrome (MetS) from the PREDIMED-Plus randomized controlled trial. Dietary intake information was obtained at baseline, 6- and 12-months from a validated 143-item semi-quantitative food-frequency questionnaire, and CQI (range: 4 to 20) was calculated based on four dietary criteria: total dietary fibre, glycemic index, wholegrain/total grain carbohydrate ratio, and solid/total carbohydrate ratio. Overall and regional adiposity (total body fat, visceral fat and android-to-gynoid fat ratio) was quantified using dual-energy X-ray absorptiometry at all three time points. Multiple adjusted linear mixed-effects models were used to assess associations between concurrent changes in repeatedly measured CQI and adiposity over time.ResultsAfter controlling for potential confounding factors, a 3-point increment in CQI over 12-month follow-up was associated with a decrease in visceral fat (β -0.067 z-score, 95% CI -0.088; -0.046, p < 0.001), android-to-gynoid fat ratio (-0.038, -0.059; -0.017, p < 0.001), and total fat (-0.064, -0.080; -0.047, p < 0.001). Fibre intake and the ratio of wholegrain/total grain showed the strongest inverse associations with all adiposity indicators.ConclusionsIn this prospective cohort of older adults with overweight/obesity and MetS, we found that improvements in dietary carbohydrate quality over a year were associated with concurrent favorable changes in visceral and overall fat deposition. These associations were mostly driven by dietary fibre and the wholegrain/total grain ratio.Trial registrationThe trial was registered at the International Standard Randomized. CONTROLLED TRIAL: (ISRCTN: http://www.isrctn.com/ISRCTN89898870) with number 89898870 and registration date of 24 July 2014, retrospectively registered.

Project description:Background: The assessment of severity is crucial in the management of community-acquired pneumonia (CAP). It remains unknown whether updating cut-off values of severity scoring systems orchestrate improvement in predictive accuracy.Methods: 3,212 patients with CAP were recruited to two observational prospective cohort studies. Three bettered scoring systems were derived from the corresponding well-established and extensively used pneumonia-specific severity scoring systems, i.e. pneumonia severity index, minor criteria and CURB-65 (confusion, urea >7 mmol/L, respiratory rate ≥30/min, low blood pressure, and age ≥65 years) score, with the updating cut-off values for tachypnea and low blood pressure. Cronbach α was employed to determine construct validity. Discrimination was valued by calculating the area under the receiver operating characteristic curve (AUROC) and net reclassification improvement (NRI).Results: Respiratory rate ≥22/min and systolic blood pressure ≤100 mm Hg were performed better than respiratory rate ≥30/min and hypotension for predicting mortality in the derivation cohort, respectively (AUROC, 0.823 vs 0.519, 0.688 vs 0.622; NRI, 0.61, 0.13). Bettered scoring systems orchestrated higher convergences, indicated by greater Cronbach α and more decrease in Cronbach α if the updating cut-off values were deleted. The six scoring systems agreed well with one another. Bettered- pneumonia severity index, minor criteria and CURB-65 score showed higher associations with severity and mortality rates and demonstrated greater predictive accuracies for mortality compared with the corresponding original systems (AUROC, 0.939 vs 0.883, 0.909 vs 0.871, 0.913 vs 0.859; NRI, 0.113, 0.076, 0.108; respectively). The validation cohort confirmed a similar pattern.Conclusions: Updating cut-off values of severity scoring systems for CAP orchestrate improvement in predictive accuracy, suggesting that it may facilitate the rationalization of clinical triage decision-making and further reduce mortality. The current studies provide the first known prospective evidence of potential benefit of the updating cut-off values of severity scoring systems for CAP in predictive accuracy.Key messagesUpdating cut-off values were performed better for predicting mortality.Bettered scoring systems orchestrated higher convergences.Bettered scoring systems demonstrated greater predictive accuracies for mortality.

Dataset Information

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

Publications

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

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