COMPARISON OF SEVERAL EQUATIONS AND DERIVATION OF A NEW EQUATION FOR CALCULATING BASAL METABOLIC-RATE IN OBESE CHILDREN

Objectives: To compare basal metabolic rate (BMR) calculated by the Ha rris-Benedict, Ravussin, Cunningham, World Health Organization (WHO) a nd Schofield equations to BMR determined in an obese pediatric populat ion. The second objective is to derive a new equation, based on measur ed BMR in obese children, for calculating BMR in obese pediatric patie nts. Methods: The study included 110(50 male/60 female) healthy obese subjects (BMI>28) (11.7 +/- 2.8 years, 73 +/- 27 kg, 152 +/- 14 cm and 38 +/- 6% fat) who had preprandial BMR determined by indirect calorim etry. These results were compared to BMR calculated with the five abov e mentioned equations. Fat-free mass was determined by bioelectrical i mpedance and body composition was calculated using the appropriate equ ation. The age groups analyzed were as follows: males 3 to 10 and 11 t o 18 years old; females 3 to 10 and 11 to 18 years old. A new equation was derived by stepwise multiple regression analysis using 100 random ly selected subjects from our test group and tested using the remainin g 10 subjects. Results: Basal metabolic rate calculated by the Ravussi n and Cunningham equations in all subgroups was lower (p<0.05) than me asured BMR. Basal metabolic rate calculated by the Harris-Benedict equ ation was lower (p<0.05) than measured BMR in male populations ages 3 to 10, 11 to 18, and in the entire cohort. Measured BMR was overestima ted by the Harris-Benedict equation (p<0.05) in females 11 to 18 years old; by the WHO equation (p<0.05) in both male and females 3 to 10 ye ars old and by the Schofield equation (p<0.05) in males 11 to 18 years old. In comparison to measured BMR, the WHO equation appeared to be t he most accurate for estimating BMR in males and females 11 to 18 year s old. However, BMR calculated using our new equation in the 10 test s ubjects was similar to measured BMR. Conclusions: The WHO equation was the most accurate of the prediction equations studied. However, our n ew prediction equation may be more appropriate for calculating BMR in an obese pediatric population.