Younger Adults with HIV Experience Shorter Times to Viral Rebound

JULY 16, 2018
Kenneth Bender, PharmD, MA
Robert Hogg, MSc, PhDRobert Hogg, MSc, PhD
A Canadian study found that a patient's age was a factor in HIV viral rebound after suppression with treatment, with younger adults experiencing lower prevalence of viral suppression and shorter time to viral rebound than older adults.

"There is an age effect," principle investigator Robert Hogg, MSc, PhD, British Columbia Centre for Excellence in HIV/AIDS, Vancouver, and Simon Fraser University, Burnaby, British Columbia, Canada, told MD Magazine®. "However, I think the important point here is that specific subpopulations at all ages are more at risk of not suppressing, or rebounding if they do, than the other people in the cohort," Hogg said.

Hogg and colleagues in the Canadian Observational Cohort (CANOC) Collaboration have investigated several socio-demographic factors to determine whether any might predict or contribute to HIV viral suppression and rebound, including having compared indigenous and non-indigenous Canadian populations infected with HIV.

In the present study, the researchers sought to distinguish between adults ≤29 years of age and older adults for prevalence and correlates of viral suppression. They identified 9031 HIV-positive adults in 3 of Canada's most populous provinces, including 1281 individuals ≤29 years of age, who had initiated antiretroviral therapy between 2008-2011 or 2012-2013.

The researchers defined viral suppression and rebound from at least 2 consecutive viral load measurements of <50 or >50 HIV-1 RNA copies/ml, respectively, at least 30 days apart, in a 1-year follow-up period. Of the participants, 477 were excluded for not meeting these criteria, but the number excluded was not significantly different between age groups.

Factors considered as possible covariates of suppression and rebound included age, sex, province of residence, ethnicity, and behavioral transmission risk category. Clinical variables included hepatitis C virus (HCV) co-infection (ever), presence of AIDS symptoms, baseline CD4 cell count, and HIV plasma viral load. Treatment factors included the "era" of initial antiretroviral treatment and the particular regimen.

Hogg and colleagues found an association of age with viral suppression and rebound but characterized it as "modest." Analysis with bivariate and unadjusted accelerated failure time (APT) models indicated that there was a 1% increase in the rate of viral suppression for each 1-year increase in age. Viral suppression was associated with other factors, however, including being male, having a baseline CD4 cell count above 200 cells/mm3, and a later era of antiretroviral initiation.

"Our analysis revealed that key covariates of viral suppression and rebound for young adults in Canada are similar to those of known importance to adult adults," the researchers reported.

From these data, they do suggest that women, people who use injection drugs, and people with indigenous ancestry could benefit from particular targeting for health interventions. The researchers also noted that the younger adults in the study had better outcomes compared with other large cohort studies, although they suggest that those differences may be explained by systematic differences between the health systems in the UK, USA, and Canada.

The relatively better outcomes in this cohort were also noted by Hogg in comments to MD Mag. "Overall rates of suppression are high, which is promising," he said.

The report, “Viral Suppression and Viral Rebound Among Young Adults Living with HIV in Canada,” was published online in Medicine.

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