Universal test-and-treat improves population viral suppression in rural South Africa
22nd International AIDS Conference, Amsterdam, Netherlands, July 23-27, 2018


Mark Mascolini

A universal test-and-treat approach to HIV management improved population viral suppression in the ANRS TasP trial in rural South Africa, more through universal testing than universal treatment [1]. Randomization to immediate testing and treatment did not cut HIV incidence--the new-infection rate. 

Universal test-and-treat involves testing everyone at risk for HIV infection and immediately treating those who test positive. The strategy aims to maximize the proportion of people living with HIV who get antiretroviral therapy (ART) and achieve viral suppression--and thus to boost population-level suppression and limit HIV transmission. Mathematical modeling predicts that universal test-and-treat will cut HIV incidence and perhaps eliminate HIV epidemics. 

One of 5 international test-and-treat trials, ANRS 12249 TasP is a cluster-randomized trial in the rural Hlabisa subdistrict of South Africa's KwaZulu Natal province. Running from March 2012 through June 2016, the trial enrolled people at least 16 years old. The subdistrict has about 28,000 adult residents and an HIV prevalence around 30%. Only 10% of residents have jobs, and migration is frequent. 

HIV counselors visited all local households and counted resident adults. Eligible participants completed a sociodemographic and sexual behavior questionnaire and gave a finger-prick sample to allow HIV testing of dried blood spots. Counselors repeated these home-based tests and surveys every 6 months and recorded deaths and out-migrations. Everyone who tested positive for HIV or reported HIV infection got referred to a local clinic within 45 minutes walking distance. Clinics in control clusters offered ART according to national guidelines; clinics in test-and-treat clusters offered immediate ART regardless of CD4 count or clinical stage. 

Four clusters opened in 2012, 6 in 2013, and 12 in 2014. Follow-up continued in all clusters through mid-2016. As previously reported, HIV incidence did not differ significantly between the two trial arms [2]. The current analysis asked whether population viral suppression improved during the course of the trial and whether change in population viral suppression differed between study arms. 

The ANRS team used multiple sources to estimate daily HIV status. They used data on clinic visits, ART prescriptions, and CD4 count to estimate how many people with HIV entered care and started ART, and how many treated people reached a viral load below 400 copies. They defined population viral suppression as the proportion of resident adults with HIV in care, on ART, and with a viral load below 400 copies. The researchers computed population viral suppression before the intervention and per day as soon as they completed the initial population census. 

Pre-intervention population viral suppression was slightly but significantly lower in the test-and-treat arm than in the control arm (23.5% versus 26.0%, 
P = 0.028). Through January 1, 2016, the population viral suppression rate rose significantly to 46.2% in the test-and-treat arm (+22.8%, P < 0.001) and to 44.6% in the control arm (+18.6%, P < 0.001). The 2016 suppression rate did not differ significantly between the test-and-treat arm and the control arm (46.2% and 44.6%, P = 0.208).

The researchers used a mixed linear model to explore relations between population viral suppression and calendar time, time since cluster opening, trial arm, and interaction between arm and time since cluster opening. This analysis adjusted for cluster-level sociodemographic changes. Modeling suggested that time since cluster opening mainly drove the increase in population viral suppression. The analysis indicated that the impact of universal treatment was smaller than the impact of universal testing because of low linkage to care. 

The investigators concluded that a universal test-and-treat strategy significantly improved population viral suppression over time in rural South Africa, even though it did not lower HIV incidence more than in the control arm [2]. The ANRS team noted that they did not power the trial to measure whether HIV incidence fell over time within each arm but to compare overall incidence between arms. 

References
1.
Lamarange J, Diallo MH, McGrath N, et al. Temporal trends of population viral suppression in the context of universal test and treat: results from the ANRS 12249 TasP trial in rural South Africa. AIDS 2018: 22nd International AIDS Conference, Amsterdam, Netherlands, July 23-27, 2018. Abstract TUAC0103.
2. Iwuji CC, Orne-Gliemann J, Larmarange J, et al; ANRS 12249 TasP Study Group. Universal test and treat and the HIV epidemic in rural South Africa: a phase 4, open-label, community cluster randomised trial. Lancet HIV. 2018;5:e116-e125. 
https://www.ncbi.nlm.nih.gov/pubmed/29199100