BMI-based obesity cutoffs and excess adiposity in a Caribbean adolescent population of African origin

Abstract

Objective: To evaluate the diagnostic utility of recommended body mass index (BMI)-based classification systems in detecting excess body fat (BF) in an Afro-Caribbean adolescent population. Subjects: All adolescents aged 12-18 years were invited to participate in the study. A total of 3749 persons participated fully in the study. Result: Males (12.2%) (95% confidence interval (CI): 10.7, 13.9) and females (43.6%) (95% CI: 41.5, 45.7) had excess adiposity. Specificities were high for all cutoff values (range 90.1-99.7%). Sensitivities ranged from 25.7 to 86.4% and from 15.6 to 54.4% for Centre for Disease Control (CDC) and International Obesity Task Force (IOTF) cutoff values, respectively. The mean areas under the receiver-operating characteristic curves ranged from 62.7 to 88.2% in males and 57.7 to 75.1% in females, while positive likelihood ratios ranged from 8.7 to 90.9 for the recommended BMI cutoff values. Conclusions: Overall, the CDC cutoffs had a higher sensitivity than the IOTF cutoffs in screening for excess fat. Specificities were high for cutoff values in both systems and would produce fewer false negatives.

Performance of references based on body mass index for detecting excess body fatness in schoolchildren aged 7 to10 years

“…In 6991 Singaporean adolescents aged 12 to 18 years, the sensitivities and specificities of WHO-2007 criteria using the top 5% of body fatness (estimated by four skinfolds measurements) as the reference standard were 69.4 and 95.0% for boys; 53.0 and 98.1% for girls, respectively 10 . The present study found small differences in values of specificities between boys and girls (but only for WHO-2007 reference), whereas the BMI classification systems analyzed by other studies showed, in general, better sensitivity for boys and better specificity for girls [4][5][6]10,13 . A systematic review study1 showed higher values of sensitivity and similar values of specificity for obesity definition when a national reference data was compared to the IOTF approach.…”

“…Most studies that evaluated the performance of recommended BMI cut-off values of the reference system based their comparisons on estimates of sensitivity and specificity [3][4][5][6][7][8][9][10][11][12][13] . In this study the above-mentioned measures were used to compare the two classification systems, whereas the LR estimation was used to select the optimal cut-offs in each curve, allowing the calculation of the post-test probabilities for each BMI reference.…”

“…Previous studies on diagnostic accuracy of BMI used summary statistics, such as sensitivity and specificity, area under the curve 3,[5][6][7][8][10][11][12] , and likelihood ratio (LR) analysis 5,10,13 . resumO: Objetivo: Comparar a sensibilidade e especificidade de sistemas de classificação baseados no índice de massa corporal (IMC) e determinar os melhores pontos de corte na predição do excesso de gordura corporal em escolares.…”

Sensibilidade e especificidade dos sistemas de classificação para sobrepeso baseados no índice de massa corporal em crianças de 7-10 anos de idade.

“…In general, better sensitivity was found for boys and better specificity for girls 5,8,11,18,21 . Several studies compared the diagnostic accuracy between national and international BMI references, and found better sensitivity using the national references 5,7,8,21,24 .…”

“…Previous studies on the diagnostic accuracy of BMI-based classification systems when screening individuals with excess body fat have used statistical analyses such as sensitivity and specificity [3][4][5][6] , area under the Receiver Operating Characteristic (ROC) curve [7][8][9][10] , and likelihood ratio 7,10,11 . In most studies, a significantly higher sensitivity was reported for national references when compared with the references of the International Obesity Task Force (IOTF) [3][4][5]7,8 or of the World Health Organization (WHO-2007) 5 , and the opposite for specificity 3,5,8 .…”