Effects of HIV and Antiretroviral Therapy on Resting Metabolic Rate Among Postpartum Women

Background: Historically resting metabolic rates (RMRs) were higher among people living with human immunodeficiency virus (HIV+) compared to HIV negative (HIV-). However, with newer generation antiretroviral therapies (ART) and better infection control, RMRs are now similar. There are, however, limited data comparing RMR in HIV+ postpartum (PP) women and the effect of ART. We compared RMRs between healthy controls (HIV-) and HIV+ PP women using dolutegravir-based (DTG) or Efavirenz-based (EFV) ART. Methods: In this cross-sectional study the sample consisted of 65 HIV+ and HIV- women between ages 18-45 years attending their 6 months PP study visit in South Africa. Body composition was measured using dual-energy x-ray absorptiometry and RMR (kcal/day) by indirect calorimetry. The RMR predicted by Mifflin and Cunningham equations were compared with the measured RMR. The measured RMR was divided by fat free mass (FFM) to obtain the RMR expended per kilogram (kg) FFM (RMR/FFM). Linear regression analysis was performed to assess association between the HIV status and the maternal measured RMR. Data is reported at mean (standard deviation). Results: Of the 65 participants, 29.2%, 33.8% and 36.9% were HIV-, HIV+ using DTG and EFV ART, respectively. HIV- women were younger (28.0 (5.7) years), weighed more (85.8 (22.2) kg), had higher fat (41.0 (15.1) kg) and FFM (42.0 (7.4) kg). HIV+ women using EFV weighed less (71.0 (18.6) kg) and presented with both a lower fat (44.2 (6.4) kg) and FFM (37.5 (6.4) kg) compared to those using DTG. The age adjusted average RMR/FFM was significantly lower among HIV+ women using EFV ART (mean difference [95% CI]: 3.17 [0.46,5.88] kcal/kg/day, p=0.02) compared to HIV- women. While age adjusted average RMR/FFM did not differ significantly between HIV+ women using DTG ART and HIV- women (mean difference [95% CI]: -1.07[-3.67,1.52] kcal/kg/day, p=0.413). Conclusions: The data from this study indicated that PP HIV+ women using EFV-based ART had a higher energy expenditure per kg FFM compared to HIV- women, while HIV+ women using DTG-based ART showed no differences compared to HIV- women. A better understanding of the longitudinal effect of HIV and ART on energy balance is needed to allow clinicians to optimize treatments among PP women.