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

BackgroundStudies have reported that children who are obese are becoming more severely obese. ObjectiveWe aimed to classify obese children based on age- and gender-specific centile curves passing through body mass index (BMI) 30, 35 and 40 at age 18 as class I', class II' or severe, and class III' or morbid obesity. MethodsIn addition to the International Obesity Task Force BMI cut-offs corresponding to BMI 30 and 35, we calculated the BMI cut-offs corresponding to BMI 40 using the LMS method proposed by Cole and Lobstein. We classified 217 obese children according to these criteria. ResultsFifty-six (25.8%) children had class III obesity, 73 (33.6%) class II obesity and 88 (40.6%) class I obesity. Class III obese children had a higher waist circumference, systolic blood pressure and fasting insulinaemia compared with less obese children. ConclusionIt is clinically important to classify obese children in different classes of obesity severity.