Changes in Waist Circumference in People Taking ART

One of the undesirable potential side effects of taking antiretroviral therapy (ART) drugs can be weight gain. In a new study, a team of investigators looked at data from a clinical trial testing 3 different ART regimens in order to determine the factors that can lead to enlarging waistlines in patients with HIV.

The investigators, from the University of California Los Angeles, Emory School of Medicine in Atlanta, and other institutions, examined the results from a trial in which more than 1800 participants were randomized to receive tenofovir disoproxil fumarate/emtricitabine with either raltegravir (RAL), atazanavir/ritonavir (ATV/r), or darunavir/ritonavir (DRV/r). The participants, three-quarters of whom were male, were followed for nearly 2 years after beginning the regimens. The average waist circumference at baseline was 90.6 centimeters, which had grown by 3.4 centimeters at 96 weeks.

All gains were not equal, however. Those in the RAL arm of the trial had an average waist size of 90.7 centimeters at baseline, which increased 4 centimeters by week 96. The participants taking ATV/r started with an average waist size of 91.2 centimeters, with an increase of 3.3 centimeters at 96 weeks. The participants who took DRV/r were comparatively the slimmest, with an average beginning waist measurement of 89.9 centimeters and an increase of 2.8 centimeters 96 weeks later.

“Results from this study indicated that ART initiation was associated with increases in [waist circumference],” the investigators wrote. “These increases were more pronounced with the RAL-based regimen relative to DRV/r, and the strength depended on sex and race/ethnicity.”

These remarks refer to the greater waist circumference gains seen by both women and black and Hispanic participants. The average waist circumference of female participants increased by 4.1 centimeters compared with 3.2 centimeters in male participants. Black participants saw an average waist increase of 4 centimeters, Hispanic participants experienced a gain of 3.7 centimeters, and white subjects’ average increase was 2.6 centimeters.

But it was when looking at different combinations of gender, race, and medication that the impact of treatment type plus personal factors became apparent to the investigators. Consider the average waist increase for a black female in the RAL treatment arm: 6.9 centimeters. For a black male taking RAL, the average waist increase was 4.6 centimeters. However, black women taking DRV/r saw a mean gain of only 2.5 centimeters, while the waist sizes of black men on the same regimen increased just 2.2 centimeters.

Another factor influencing waist increases was whether HIV was advanced at the beginning of the study. Subjects with a viral RNA load of 100,000 copies/mL or greater had an average waist circumference expansion of 6.3 centimeters after starting ART, while those whose RNA levels were below 100,000 copies/mL saw their waists grow by 2.1 centimeters. Similarly, participants with CD4 levels below 350 had an average waist expansion of 4.6 centimeters after ART initiation, compared with the average 1.6-centimeter gain in those who had CD4 levels at or above 350. These results, the investigators said, highlight the benefits of beginning ART as early as possible once a person is diagnosed with HIV.

The investigators noted that their study “did not confirm sex and race/ethnicity as individual predictors of abdominal fat changes,” as they wrote in the discussion section of their report, but rather highlighted that different ART regimens yield different results in a diverse population. “[I]t is important to understand the inherent differences in patient characteristics, especially HIV disease severity, and treatments that may affect such outcomes,” they wrote. “Understanding treatment differences for females, males, and race/ethnicity groups, as well as other key baseline predictors, will allow health providers to determine therapeutic approaches better suited to preventing central fat accumulation.”