Sensitivity and specificity of criteria for classifying body mass index in adolescents

Abstract

OBJECTIVE: To estimate the prevalence of overweight among adolescents using different body mass index (BMI) classification criteria, and to determine sensitivity and specificity values for these criteria. METHODS: Weight, height, and tricipital and subscapular skinfolds in 934 adolescents (462 males and 472 females) aged 14-18 years (mean age 16.2; SD=1.0) of the city of Florianópolis, Southern Brazil, in 2001. Percent fat estimated based on skinfold measurements (e"25% in males and e"30% in females) was used as a gold-standard for determining specificity and sensitivity of BMI classification criteria among adolescents. RESULTS: The different cutoff points used for classifying BMI in general resulted in similar prevalence of overweight (p>;0.05). Sensitivity of the evaluated criteria was high for males (85.4% to 91.7%) and low for females (33.8 to 52.8%). Specificity of all criteria was high for both sexes (83.6% to 98.8%). CONCLUSIONS: Estimates of prevalence of obesity among adolescents using different BMI classification criteria were similar and highly specific for both sexes, but sensitivity for females was low.