Investigating Heterogeneity in Studies of Resting Energy Expenditure in Persons with HIV/AIDS, a Meta-analysis

Smart Foods Centre, University of Wollongong, Australia.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 03/2005; 81(3):702-13.
Source: PubMed


There is conflict in the literature about the extent of alterations of resting energy expenditure (REE) in persons with HIV.
The study was conducted to ascertain the mean difference in REE (in kJ) per kilogram of fat-free mass (FFM; REE/FFM) between HIV-positive subjects and control subjects and to investigate heterogeneity in the literature.
A meta-analysis comparing classical and Bayesian methods was conducted. Heterogeneity was investigated by using subgroup analysis, metaregression, and a mixed indirect comparison.
Of 58 studies meeting the inclusion criteria, 32 included both HIV-positive and control groups; 24 of these 32 were included. Thirty-seven studies were used in the mixed indirect comparison, and 30 were used in the subgroup comparisons of the HIV-symptomatic, lipodystrophy, weight-losing, and weight-stable subgroups and the healthy (HIV-negative) control group. Mean REE/FFM was significantly higher in 732 HIV-positive subjects than in 340 control subjects [11.93 kJ/kg (95% CI: 8.44,15.43 kJ/kg) and 12.47 kJ/kg (95% CI: 8.19,16.57 kJ/kg), classical and Bayesian random effects, respectively]; the test for heterogeneity was significant (P < 0.001). Both the mixed indirect comparison and the subgroup analysis indicated that REE/FFM was highest in the symptomatic subgroup; however, the small number of studies investigating symptomatic subjects limited statistical comparisons. The presence of lipodystrophy, use of highly active antiretroviral therapy, subject age, and method of body-composition measurement could not explain the heterogeneity in the data with the use of metaregression.
REE/FFM (kJ/kg) is significantly higher in HIV-positive subjects than in healthy control subjects. Symptomatic HIV infection may contribute to the variations reported in the literature.

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    • "The resting energy expenditure per kilogram of fat-free mass (kcal/kg) (REE/FFM) was significantly higher in HIV-infected patients with lipodystrophy (approximately 15%) than in the controls and 9% higher than in the HIVþLIPOÀ group. Batterham [16] performed a meta-analysis suggesting that the energy expenditure of HIV-infected patients with a stable weight did not differ from those who have lipodystrophy, but the REE/ FFM in HIV-infected patients was approximately 9% higher than in the control group. "
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