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Greater Population-Level Viral Control Tied to Lower HIV Incidence in 4 Large Trials
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CROI 2020, March 8-11, 2020, Boston
Mark Mascolini
Universal test and treat (UTT) trials in Africa linked both population-level HIV load (viremia) and nonsuppression of HIV to HIV incidence (the new diagnosis rate) [1]. UTT investigators confirmed these findings in each of four large studies across a "wide range of epidemic settings in sub-Saharan Africa."
An international team used data from four cluster-randomized UTT trials to explore three issues: (1) the relationship between HIV viremia in all adults and HIV incidence, (2) the relationship between viral suppression in HIV-positive adults and HIV incidence, and (3) consistency of UTT primary trial results.
Four big UTT trials already showed that universal population-based HIV testing followed by energetic linkage to care and universal treatment can quickly raise rates of population-level HIV suppression to levels above those seen in other regions of sub-Saharan African and even in the United States.
The new analysis involved study settings in 105 communities in Botswana (Ya Tsie study), South Africa (TasP, ANRS 12249), Zambia and South Africa (PopART, HPTN 071), and Kenya and Uganda (SEARCH). All four studies were cluster-randomized trials and all provided population-based universal HIV testing--either to one or all study arms.
The studies all made population-based estimates of HIV prevalence, HIV incidence, and viral nonsuppression. All studies defined viral nonsuppression as the percentage of all HIV-positive persons (regardless of antiretroviral use) with a viral load above 400 or 500 copies. They defined population viremia as the percentage of all adults (with or without HIV) with viral nonsuppression. All four studies measured HIV incidence by repeat testing of HIV-negative cohorts. The researchers used community-level linear regression to assess the relationship between HIV incidence and viremia and the relationship between HIV incidence and nonsuppression.
In the combined 105 communities studied, HIV prevalence in more than a quarter million people ranged from 2% to 40%. Viral nonsuppression in almost 40,000 people with HIV ranged from 3% to 70%. And HIV incidence calculated in more than 345,000 person-years ranged from 0.03 to 3.4 infections per 100 person-years.
Across the four studies, higher viremia meant higher HIV incidence. Every 1% absolute increase in viremia led to a 0.07 per 100 person-years jump in incidence (95% confidence interval [CI] 0.05 to 0.10, P < 0.001). This association between viremia and incidence held true in each of the four studies.
The analysis also linked HIV nonsuppression to higher HIV incidence, again in all four studies. Incidence rose 0.12 per 100 person-years for each 10% absolute increase in viral nonsuppression (95% CI 0.01 to 0.23, P = 0.03).
The UTT intervention in all trials led to large gains in population-level viral suppression over time. Between-arm differences in viral suppression in these studies, the researchers found, largely explained between-arm differences in HIV incidence.
The investigators believe these UTT trials "provide consistent support for the finding that increasing population level viral suppression reduces HIV incidence." Therefore, they added, these studies "further provide a model for achieving such reductions [at the] population level quickly."
Reference
1. Petersen M, Larmarange J, Wirth K, et al. Population-level viremia predicts HIV incidence across universal test and treat studies. Conference on Retroviruses and Opportunistic Infections (CROI). March 8-11, 2020. Boston. Abstract 47.
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