People living with HIV in the U.S. are experiencing increases in body mass index (BMI) at a rate three times greater than that of the general U.S. population, according to newly presented research. The findings, presented during the 23rd International AIDS Conference (AIDS 2020), provide context for the ongoing debate around the role of HIV and specific antiretrovirals in weight gain and metabolic concerns among people with HIV.
Study Construction: A Long-Term Look at Body Mass in Privately Insured People
Michael J. Silverberg, Ph.D., M.P.H., a research scientist with the massive integrated health care provider Kaiser Permanente Northern California, presented the findings during a virtual session of AIDS 2020, which is being held online this year due to the COVID-19 pandemic. Silverberg and several colleagues conducted a cohort study involving nearly 138,222 people, 8,256 of whom were people living with HIV (PLWH), who received long-term care through Kaiser Permanente in California, Maryland, Virginia, and Washington, D.C.
All PLWH included in the study (all of whom were at least 21 years old) received care at Kaiser Permanente from 2000 through 2016; each PLWH was frequency matched with 10 HIV-negative people based on several factors, including age, race, and sex. The average participant age was 41 among PLWH and 42 among HIV-negative participants. Nearly nine out of 10 participants were male, and two-thirds of PLWH identified male-to-male sex as their HIV risk factor. That said, there was significant racial diversity within the cohort (among PLWH, 36% were white, 26% Black, and 26% Latinx).
Study Findings: Steady Weight Gain, Especially Among People With HIV
Silverberg et al focused their analysis on the 2006-to-2016 period, during which BMI data was electronically recorded by Kaiser Permanente providers. At baseline, PLWH tended to have a lower BMI than their HIV-negative counterparts:
- 44% of PLWH had a normal BMI (between 18.5 and 24.9 kg/m2) compared to 24% of HIV-negative participants.
- Obesity was twice as common among HIV-negative participants (37%) at baseline than among PLWH (18%).
- While 53% of PLWH had a baseline BMI of 25 kg/m2 or higher, the same was true for 75% of HIV-negative participants.
Over time, however, that gap progressively narrowed over the course of the study’s 12-year follow-up period, Silverberg et al found:
- The average BMI at baseline was 25.8 kg/m2 for PLWH and 28.7 kg/m2 for HIV-negative people.
- After 12 years, average BMI had risen to 28.4 kg/m2 for PLWH and 29.4 kg/m2 for HIV-negative people (both of which are in the upper portion of the “overweight” category).
- BMI increased steadily throughout those 12 years, at a rate of 0.22 kg/m2 per year among PLWH compared to 0.06 kg/m2 per year among HIV-negative people.
- That equates to a roughly three-fold higher rate of BMI increase among PLWH than their HIV-negative counterparts.
This closing of the BMI gap occurred among all weight classifications:
- Among normal-weight or underweight participants (i.e., baseline BMI below 25 kg/m2), BMI increased by 0.31 kg/m2 per year among PLWH compared to 0.20 kg/m2 per year among HIV-negative participants.
- Among overweight participants (i.e. baseline BMI between 25 and 30 kg/m2), BMI increased by 0.18 kg/m2 per year among PLWH compared to 0.09 kg/m2 per year among HIV-negative participants.
- Among obese participants (i.e. baseline BMI of 30 kg/m2 or higher), BMI increased by 0.07 kg/m2 per year among PLWH, while it decreased by 0.02 kg/m2 per year among HIV-negative participants.
In fact, the stratified analysis found that, from the beginning of the study period to the end, PLWH went from having an average BMI lower than that of their HIV-negative counterparts to having an average BMI that was slightly higher. “BMI is increasing more rapidly over time for people living with HIV after they initiate [antiretroviral therapy],” Silverberg said, “and may soon exceed levels of demographically similar uninfected people in the U.S.”
An Unanswered Question: What’s Causing Weight Gain Among People With HIV?
To be sure, this study provided just one examination of one weight-related measurement in a specific subset of the U.S. population. As Silverberg noted in his presentation, BMI is not an ideal measurement tool on its own, due to its inability to differentiate between muscle and fat mass.
The heavily male demographic also makes the applicability of the findings to women questionable; the study presentation did not break results down by sex, nor did it mention transgender participants. Further, the study had no way to account for the potential impact of lifestyle changes (e.g., diet or exercise) on BMI changes, and it by definition only included people with private health insurance (i.e., a Kaiser Permanente plan).
Nonetheless, the findings provide a high-level glimpse at the broader trends that have been taking place on the scales of PLWH in the U.S. relative to HIV-negative people, and can be useful as other research attempts to tease out the role that individual antiretrovirals have been playing in weight gain among PLWH.
A growing amount of research in recent years has focused on the potential effect of integrase inhibitors, particularly dolutegravir, on weight gain. The same goes for tenofovir alafenamide, the newer formulation of tenofovir disoproxil fumarate that appears friendlier on bones and kidneys than the original—but also appears to trigger weight gain among a significant number of people who switch to it from their prior therapy.
These Kaiser data also provide a new set of data points for the increasingly complex conversation about long-term cardiovascular risk among PLWH, and the extent to which antiretroviral therapy mitigates or accentuates that risk. A separate analysis of Kaiser data from earlier this year revealed that, although PLWH on treatment can now reasonably expect to live a nearly identical lifespan compared to their HIV-negative peers, they also appear to spend a much larger chunk of that life managing chronic comorbidities such as cardiovascular disease.
“Given the known higher risks of BMI-related comorbidities, such as cardiovascular disease, it is critical that future research clarify the role of HIV-specific risk factors for weight gain—including the use of integrase inhibitors and other antiretrovirals—and to identify appropriate interventions,” Silverberg concluded.