Body mass index of Kuwaiti children aged 3-9 years: reference percentiles and curves

Aim: The suitability of using the standards for body mass index (BMI), produced in the US by the National Center for Health Statistics, for assessing overweight and obesity among children in Kuwait and other Arabian Gulf countries has not been examined. These standards were obtained from better-nourished and genetically different populations to those found in Kuwait and in other Gulf region countries. The purpose of this study was to develop BMI reference percentiles and curves appropriate for children aged 3-9 in these countries. Method: Attempts were made to include all healthy Kuwaiti kindergarten and elementary education children in this study The total sample was 113,013, comprising 55,053 males and 57,960 females. The children were measured for weight and height from which the BMI was calculated. Appropriate polynomial regression smoothing techniques were used to obtain the best-fitting percentile curves. Results: At percentiles <= 25th, the BMI of boys exceeded that of girls. At the 50(th) percentile, boys' BMI was mostly higher than or equal to that of the girls except at age nine where it was lower At the 75 h percentile, the BMI of both genders was similar, with exceptions at age six and nine years. At the 85(th) and 95(th) percentiles, girls' BMI was consistently higher than males. At the lowest percentile, the BMI of US children was higher than Kuwaiti, Saudi (starting at six) and Iranian children. The BMI of Kuwaiti children at higher percentiles was higher than that of Saudi, Iranian (except at age < four years) and US children. Conclusion: BMI curves for Kuwaiti children follow almost the same pattern as their US counterparts but with noticeable variations especially at the lower and higher percentiles. This study may reflect that western standards may not be directly applicable to assess the level of BMI in Kuwait and possibly in the neighbouring Gulf countries, since they may overestimate the levels of overweight, obesity and underweight.