Equation to estimate resting energy expenditure in adolescents with sickle cell anemia

Background: Basal energy requirements are higher in adolescents with sickle cell anemia (SCA) than in healthy control subjects. However, no equation is available to accurately predict their energy needs. Objective: Our objective was to develop a clinically useful equation to estimate resting energy expenditure (REE) in adolescents with SCA. Design: REE and other components of total energy expenditure were measured in adolescents with SCA (n = 37) and in control subjects (n = 23) for 24 h in a whole-room indirect calorimeter. Multiple linear regression analysis was used to describe the relations of REE with independent variables such as sex, weight, height, fat-free mass, fat mass, age, and hemoglobin concentration in adolescents with SCA. The Bland-Altman comparison technique was used to compare values predicted by existing equations with measured REE values. Results: Mean (+/-SD) measured REEs were 7746 +/- 974 and 6332 +/- 869 kJ/d in the male and female subjects with SCA, respectively, and these values were 16% higher than those in the healthy control subjects. Standard equations underestimated REE by 12% (P less than or equal to 0.001) in adolescents with SCA and overestimated REE by 4% in control subjects (P = 0.01-0.29). Several REE regression equations for SCA were developed. The most parsimonious equation for males was REE (kJ/d) = 5461 + 77.7 (.) weight (kg) - 233.2 (.) hemoglobin (g/dL), or REE (kcal/d) = 1305 + 18.6 (.) weight (kg) - 55.7 (.) hemoglobin (g/dL). For females, the most parsimonious equation was REE (kJ/d) = 4603 + 55.6 (.) weight (kg) - 126.2 (.) hemoglobin (g/dL), or REE (kcal/d) = 1100 + 13.3 (.) weight (kg) - 30.2 (.) hemoglobin (g/dL). Conclusion: The new equations have better agreement with the basal metabolic needs of adolescents with SCA than do standard predictive equations.