Understanding the Potential Impact of a Combination HIV Prevention Intervention in a Hyper-Endemic Community
Despite demonstrating only partial efficacy in preventing new infections, available HIV prevention interventions could offer a powerful strategy when combined. In anticipation of combination HIV prevention programs and research studies we estimated the population-level impact of combining effective scalable interventions at high population coverage, determined the factors that influence this impact, and estimated the synergy between the components.
We used a mathematical model to investigate the effect on HIV incidence of a combination HIV prevention intervention comprised of high coverage of HIV testing and counselling, risk reduction following HIV diagnosis, male circumcision for HIV-uninfected men, and antiretroviral therapy (ART) for HIV-infected persons. The model was calibrated to data for KwaZulu-Natal, South Africa, where adult HIV prevalence is approximately 23%.
Compared to current levels of HIV testing, circumcision, and ART, the combined intervention with ART initiation according to current guidelines could reduce HIV incidence by 47%, from 2.3 new infections per 100 person-years (pyar) to 1.2 per 100 pyar within 4 years and by almost 60%, to 1 per 100 pyar, after 25 years. Short-term impact is driven primarily by uptake of testing and reductions in risk behaviour following testing while long-term effects are driven by periodic HIV testing and retention in ART programs. If the combination prevention program incorporated HIV treatment upon diagnosis, incidence could be reduced by 63% after 4 years and by 76% (to about 0.5 per 100 pyar) after 15 years. The full impact of the combination interventions accrues over 10–15 years. Synergy is demonstrated between the intervention components.
High coverage combination of evidence-based strategies could generate substantial reductions in population HIV incidence in an African generalized HIV epidemic setting. The full impact could be underestimated by the short assessment duration of typical evaluations.
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ABSTRACT: Antiretroviral therapy (ART) significantly decreases HIV-associated morbidity, mortality, and HIV transmission through HIV viral load suppression. In high HIV prevalence settings, outreach strategies are needed to find asymptomatic HIV positive persons, link them to HIV care and ART, and achieve viral suppression. We conducted a prospective intervention study in two rural communities in KwaZulu-Natal, South Africa, and Mbabara district, Uganda. The intervention included home HIV testing and counseling (HTC), point-of-care CD4 count testing for HIV positive persons, referral to care, and one month then quarterly lay counselor follow-up visits. The outcomes at 12 months were linkage to care, and ART initiation and viral suppression among HIV positive persons eligible for ART (CD4≤350 cells/μL). 3,393 adults were tested for HIV (96% coverage), of whom 635 (19%) were HIV positive. At baseline, 36% of HIV positive persons were newly identified (64% were previously known to be HIV positive) and 40% were taking ART. By month 12, 619 (97%) of HIV positive persons visited an HIV clinic, and of 123 ART eligible participants, 94 (76%) initiated ART by 12 months. Of the 77 participants on ART by month 9, 59 (77%) achieved viral suppression by month 12. Among all HIV positive persons, the proportion with viral suppression (<1,000 copies/mL) increased from 50% to 65% (p=<0.001) at 12 months. Community-based HTC in rural South Africa and Uganda achieved high testing coverage and linkage to care. Among those eligible for ART, a high proportion initiated ART and achieved viral suppression, indicating high adherence. Implementation of this HTC approach by existing community health workers in Africa should be evaluated to determine effectiveness and costs.The Lancet HIV 11/2014; 1(2):e68-e76. DOI:10.1016/S2352-3018(14)70024-4
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ABSTRACT: The preventative effects of antiretroviral therapy for people with HIV have been debated since they were first raised. Models commenced studying the preventive effects of treatment in the 1990s, prior to initial public reports. However, the outcomes of the preventive effects of antiretroviral use were not consistent. Some outcomes of dynamic models were based on unfeasible assumptions, such as no consideration of drug resistance, behavior disinhibition, or economic inputs in poor countries, and unrealistic input variables, for example, overstated initiation time, adherence, coverage, and efficacy of treatment. This paper reviewed dynamic mathematical models to ascertain the complex effects of ART on HIV transmission. This review discusses more conservative inputs and outcomes relative to antiretroviral use in HIV infections in dynamic mathematical models. ART alone cannot eliminate HIV transmission.
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ABSTRACT: Home HIV counselling and testing (HTC) has been shown to achieve high testing coverage and linkage to care compared to existing facility-based HTC, particularly among asymptomatic persons. This study evaluates the population-level health impact and cost-effectiveness of a community-based home HTC package in KwaZulu-Natal, South Africa. We parameterized an individual-based model with data from home HTC and linkage field studies that achieved high coverage (91%) and linkage to ART (80%) in rural KwaZulu-Natal, South Africa. Costs were derived from a linked micro-costing study. The model simulated 10,000 individuals over ten years and incremental cost-effectiveness ratios (ICERs) were calculated for the intervention relative to the existing 'status quo' of facility-based testing, with costs discounted at 3% annually. Implementing home HTC in addition to current practice is predicted by the model to decrease HIV-associated morbidity by 10-22% and HIV infections by 9-47% with increasing CD4 threshold for ART initiation. Incremental programme costs were US$2.7-4.4 million higher in the intervention scenarios compared to baseline with higher costs associated with increasing ART initiation criteria; ART accounted for 48-87% of total costs. Across all ART initiation thresholds, ICERs were US$1,340, $1,090, $1,150 and $1,360 per DALY averted at ≤200, ≤350, ≤500 cells/mm(3) and universal ART access, respectively. Increases in HIV testing and linkage to care following community-based HTC propagate into population-level health outcomes. The ICERS are <20% of GDP per capita in South Africa and therefore considered very cost-effective. Home HTC should be considered a viable means by which programs can achieve ambitious new targets for HIV treatment.The Lancet HIV 04/2015; 2(4):e159-e168. DOI:10.1016/S2352-3018(15)00016-8