Evaluating the predictive ability of childhood body mass index classification systems for overweight and obesity at...

To evaluate the performance of three childhood body mass index classification systems defining weight status at age 10, for predicting overweight and obesity at 18 years, according to the World Health Organization adult body mass index classification.

Weight and height of 4235 Swedish girls and boys were measured both at around ages 10 and 18 years. Predictive ability of the extended International Obesity Task Force body mass index cut-offs (2012), the World Health Organization body mass index-for-age (2007) and a Swedish body mass index reference (2001) were assessed for sensitivity and specificity.

For predicting overweight including obesity at 18 years, the World Health Organization 2007 and the Swedish body mass index reference 2001 had similar sensitivity, 68% and 71%. The International Obesity Task Force 2012 had a significantly lower sensitivity, 53%. Specificity was 82-91% and highest for International Obesity Task Force 2012. For predicting obesity, the sensitivity for International Obesity Task Force 2012 was 29%, significantly lower than for the other two, 63% and 70%. Specificity was 94-100%, and highest for International Obesity Task Force 2012.

In situations when optimal screening sensitivity is required for identifying as many high-risk children as possible, the World Health Organization 2007 and the Swedish body mass index reference 2001 performed better than the International Obesity Task Force 2012. However, it is important to keep in mind that the International Obesity Task Force 2012 will identify the fewest false positives.