Impact of using national v. international definitions of underweight, overweight and obesity: An example from Kuwait

Abstract

Objective To compare the classification of overweight, obesity and underweight using international v. national approaches in Kuwaiti adolescents. Design Assessment of underweight, overweight and obesity using a national approach (based on Kuwaiti reference data for BMI-for-age) was compared with assessments obtained using three international approaches: the Cole et al. and International Obesity Task Force (IOTF) definitions of thinness and of overweight and obesity (Cole-IOTF); WHO 2007; and US Centers for Disease Control and Prevention (CDC) 2000 reference data and definitions. The degree of agreement between the different methods was assessed using the weighted κ statistic (κ w).Setting Two randomly selected public intermediate schools in Kuwait City. Subjects A total of 499 10-14-year-old Kuwaiti adolescents. Results Prevalence of overweight and obesity using Kuwaiti reference data (36.7 %; 95 % CI 32.4, 41.1) was significantly lower than that obtained using international approaches - Cole-IOTF (44.7 %; 95 % CI 40.3, 49.2), CDC 2000 (44.9 %; 95 % CI 40.5, 49.4) and WHO 2007 (50.5 %; 95 % CI 46.0, 55.0) (P < 0.01). All three international approaches showed almost perfect agreement: IOTF v. WHO (κ w = 0.82; 95 % CI 0.79, 0.85) and IOTF v. CDC (κw = 0.90; 95 % CI 0.87, 0.92). However, Kuwaiti reference data showed the lowest agreement with the three international approaches, the poorest being with WHO 2007 (κ w = 0.54; 95 % CI 0.49, 0.59).Conclusions Caution should be exercised when using recently collected national reference data and definitions while assessing underweight, overweight and obesity for clinical and public health applications. © 2011 The Authors.