Height-specific body mass index reference curves for Japanese children and adolescents 5-17 years of age

Background: Body mass index (BMI) reference values in consideration of height variation have not previously been reported. This study established height-specific BMI reference curves for Japanese children and adolescents aged from 5 to 17 years. Methods: The 2001 nationwide survey data were utilized for the study. First, the range of variation in BMI corresponding to height (mean +/- 2SD) at each age was compared with the range of variation in BMI corresponding to age (from minimum to maximum) at every cm height. Second, various age groups were combined, and percentile values of BMI (3rd, 5th, 15th, 50th, 85th, 95th, and 97th) were calculated for every cm height, regardless of age, and height-specific BMI reference values (males 100-179 cm, females 100-169 cm) were prepared. Results: Variation in BMI due to variation in height at each age was significantly (P < 0.05) greater than variation in BMI due to age at every cm height [males, 12.7 +/- 0.4 vs 9.2 +/- 0.4; females, 11.7 +/- 0.8 vs 8.8 +/- 0.3 (mean +/- SE)]. Conclusion: Although the use of standard values established in consideration of age and height is desirable for BMI-based guidelines for determining childhood overweight and obesity, to simplify the procedure for practical use, it is necessary to establish standard values by height, not by age. Height-specific BMI reference curves are useful for BMI-based evaluation of childhood overweight and obesity in the school health service and follow-up of obese children until adulthood.