Effect of ART Coverage on Rate of New HIV Infections in a Hyper-endemic, Rural Population: South Africa
Frank Tanser*1, T Bärnighausen1,2, E Grapsa1, and M-L Newell1,3
1Africa Ctr for Hlth and Population Studies, Univ of KwaZulu-Natal, South Africa; 2Harvard Sch of Publ Hlth, Boston, MA, US; and 3Inst of Child Hlth, Univ Coll London, UK
Background: There is as yet no empirical evidence to demonstrate that increasing ART coverage can result in a population-level decrease in HIV incidence in “real-world” Sub-Saharan African settings, where delivery of care is often not optimal and coverage of treatment varies greatly. We test the hypothesis that increasing ART coverage decreases the risk of acquisition of HIV infection in the surrounding community, in a typical rural hyper-endemic African setting.
Methods: The study uses data from longitudinal HIV and demographic surveillance hosted by the Africa Centre for Health and Population Studies in rural KwaZulu-Natal, South Africa. The population-based HIV surveillance takes place annually in all consenting resident adults ≥15 years of age (≈10,000 people/year). Using individually linked data from the district-based HIV treatment and care programme, we constructed estimates of the spatial variation in the proportion of HIV+ adults on ART across the study area for each year (2004 to 2011) (see the figure). We then followed 16,588 HIV– adults (≥15 years of age) over the same period and quantified in multi-variable survival analysis the effect of ART coverage in the surrounding local community on the risk of HIV acquisition.
Results: Between 2004 and 2011, we observed 1395 HIV seroconversions over 53,042 person-years of observation, a crude HIV incidence rate of 2.63 (95% confidence interval 2.50 to 2.77) per 100 person-years. After adjusting for individual-level sexual-behavior and socio-demographic variables associated with HIV acquisition as well as HIV prevalence in the surrounding local community, every percentage point increase in ART coverage among all HIV+ adults in a community, was associated with a1.7% decline in the hazard of HIV acquisition (p <0.001) faced by an HIV– adult living in the same community.
Conclusions: Our results demonstrate that HIV incidence can be reduced even with ART only initiated at CD4+ <200 cells/µL eligibility (and an eligibility threshold of CD4+ <350 cells/µL for pregnant women) and suggests that the recently increased treatment eligibility to CD4+<350 cells/µL for all adults, could lead to even greater reductions in HIV incidence in similar settings.
Maps showing the estimated percentage of HIV+ adults (≥15 years of age) on ART across the Africa Centre’s surveillance area (2004 to 2011).