Comparison of Resting Energy Expenditure Measured by Indirect Calorimetry and the Harris-Benedict Equation in HIV-Infected Men of Normal Body Weight

The Harris-Benedict equation (HBE) is routinely used as a method of calculating energy needs, incorporating weight, height, gender, and age as primary factors. For patients with trauma, surgery, or sepsis, additional stress factors have been developed and applied to the HBE to more accurately estimate their energy requirements. However, no stress factor has been established for patients with human immunodeficiency virus (HIV) infection. The goal of this study was to compare resting energy expenditure (REE), as calculated by HBE (REE_HBE), to resting energy expenditure measured by indirect calorimetry (REE_IC) among a group of HIV-infected patients. Twenty-nine HIV-infected men at all stages of HIV infection underwent indirect calorimetry and had the HBE simultaneously calculated. All subjects were clinically stable and had near normal body weight at the time of the study. REE_IC and REE_HBE were highly and significantly associated (r² = 0.983; p < 0.0001) and REE_IC could be estimated by the equation REE_IC = (REE_HBE) (1.127). Using Bland-Altman analysis, the mean difference between REE_IC and REE_HBE was 206.4 kcals (95% CI, -366.4 to 739.2), suggesting a poor agreement between the two measures. REE_IC was not significantly associated with peripheral blood CD4 lymphocyte count or stage of HIV illness. These data suggest that even among stable male HIV-infected patients, the HBE equation may not accurately predict REE.