Defining morbid obesity in children based on BMI 40 at age 18 using the extended international (IOTF) cut-offs

Abstract

Background. Previous studies have reported that children who are obese are becoming more severely obese. So far, however, little attention has been paid to the definition and classification of extreme obesity in children. Objective. We classified obese children based on age- and gender-specific centile curves passing through BMI 30 at age 18 as ‘class I obesity’ or ‘obesity’, through BMI 35 as ‘class II obesity’ or ‘severe obesity’, and through BMI 40 as ‘class III obesity’ or ‘morbid obesity’. Moreover, cardio-metabolic risk factors were investigated and compared across the three obesity classes. Methods. We developed the IOTF BMI cut-off of 40 kg m-², corresponding to the 99.95th percentile at age 18, using the LMS method proposed by Cole and Lobstein (2012). We classified 217 obese patients between 2 and 18 years according to IOTF criteria into three obesity groups, and retrospectively analyzed biochemical parameters of 90 patients who underwent a fasting blood sampling. Results. 56 (26%) children were classified as morbidly obese (class III obesity). Morbidly obese children had a higher waist circumference, blood pressure and fasting insulinemia compared to less obese children. Conclusion. It is important to identify morbidly obese children since this condition is associated with more serious health concerns, a higher risk for adult obesity, more aggressive treatment and a higher clinical care cost.