Population-level HIV viremia correlates with HIV incidence
Lower population-level HIV viremia correlated with decreased HIV incidence in four large Universal Test and Treat, or UTT, studies conducted in sub-Saharan Africa, according to findings from CROI.
“The results from the four major UTT trials are now available. All the trials demonstrated the ability of a universal testing approach, coupled with linkage to care and universal ART eligibility, to dramatically and rapidly increase viral suppression among people living with HIV,” Maya Peterson, MD, PhD, co-chair of the graduate group in biostatistics and associate professor in the division of epidemiology and biostatistics at University of California, Berkeley’s School of Public Health, told Healio. “Together, the trials also provide an important opportunity to evaluate the relationship between viral suppression and HIV incidence across a wide range of settings. Understanding this relationship is particularly important to guide policy, including whether to recommend universal population-based testing approaches.”
Peterson and colleagues examined data from 105 communities in the UTT trials, which include PopART, BCPP, ANRS 12249 TasP and SEARCH studies, that ranged from rural to urban and varied in the mobility of their population and sex ratio; approximately 30% to 50% were male.
The PopART trial included 21 communities in South Africa and Zambia, with approximately 25,000 adults each. BCPP was composed of 30 communities in Botswana, with approximately 3,600 adults each. ANRS 12249 TasP included 22 communities in South Africa, with approximately 1,300 adults each, and SEARCH was composed of 32 communities in Uganda and Kenya, with approximately 5,000 adults each.
HIV incidence was measured through repeat testing between 2012 and 2018. Population viremia, or the percentage of all adults with HIV viremia, regardless of HIV status, was measured at the midpoint of follow-up according to HIV prevalence and non-suppression among patients with HIV, with adjustment for differences between the measurement cohort and underlying population. Community-level regression, which was adjusted for the study, was used to calculate the correlation between HIV incidence and viremia and to assess cross-study heterogeneity.
“Population level viremia refers to the percentage of all adults in a community, both HIV-positive and HIV-negative, who have a detectable viral load,” Peterson said. “It thus incorporates both HIV prevalence and non-suppression among people living with HIV (PLWH). As a result, it reflects, to a greater extent than non-suppression alone, the probability that a random sexual encounter will result in potential HIV transmission. However, because viremia depends on prevalence, some of the association between viremia and incidence might be driven by factors that contribute to a community being both high prevalence and high incidence.”
Peterson continued: “For that reason, we also report analyses estimating the effect of increasing population level suppression among PLWH on HIV incidence, adjusting for both study and prevalence. Understanding the effect of population level viral suppression, in addition to viremia, on incidence is also of interest because it is population level suppression among PLWH that UTT interventions most directly affect.”
The final analysis included measurements of HIV prevalence in 257,929 persons, including 37,006 people from PopART, 12,570 people from BCPP, 20,978 people from TasP and 187,375 people from SEARCH.
HIV prevalence ranged from 2% to 40% by community. Nonsuppression among HIV-positive patients, which was measured in 39,928 persons, ranged from 3% to 70%. HIV incidence, which was measured over 345,844 person-years, ranged from 0.03 to 3.4 per 100 person years.
When pooling across studies, HIV incidence declined by 0.07 per 100 person years (95% CI, 0.05-0.10) for each 1% absolute decrease in viremia. Incidence significantly correlated with viremia in each study; however, both strength of the incidence-viremia relationship and projected incidence at zero percent viremia differed.
“The fewer people with detectable viral loads, the fewer new HIV infections there will be,” Peterson said. “These findings support the potential for universal testing — combined with robust linkage and care delivery systems for HIV-positive persons — as a means to reduce new HIV infections on a population level,” Peterson said. – by Caitlyn Stulpin
Reference:
Peterson M, et al. Abstract 47. Presented at: Conference on Retroviruses and Opportunistic Infections; March 8-11, 2020; Boston.
Disclosures: Peterson reports no relevant financial disclosures.