Using mathematical models to understand the impact of universal therapy for HIV serodiscordant couples

Estimating the impact of universal antiretroviral therapy for HIV serodiscordant couples through home HIV testing: insights from mathematical models.

Roberts ST, Khanna AS, Barnabas RV, Goodreau SM, Baeten JM, Celum C, Cassels S. J Int AIDS Soc. 2016 May 11;19(1):20864. doi: 10.7448/IAS.19.1.20864. eCollection 2016.

Introduction: Antiretroviral therapy (ART) prevents HIV transmission within HIV serodiscordant couples (SDCs), but slow implementation and low uptake has limited its impact on population-level HIV incidence. Home HIV testing and counselling (HTC) campaigns could increase ART uptake among SDCs by incorporating couples' testing and ART referral. We estimated the reduction in adult HIV incidence achieved by incorporating universal ART for SDCs into home HTC campaigns in KwaZulu-Natal (KZN), South Africa, and southwestern (SW) Uganda.

Methods: We constructed dynamic, stochastic, agent-based network models for each region. We compared adult HIV incidence after 10 years under three scenarios: (1) "Current Practice," (2) "Home HTC" with linkage to ART for eligible persons (CD4 <350) and (3) "ART for SDCs" regardless of CD4, delivered alongside home HTC.

Results: ART for SDCs reduced HIV incidence by 38% versus Home HTC: from 1.12 (95% CI: 0.98-1.26) to 0.68 (0.54-0.82) cases per 100 person-years (py) in KZN, and from 0.56 (0.50-0.62) to 0.35 (0.30-0.39) cases per 100 py in SW Uganda. A quarter of incident HIV infections were averted over 10 years, and the proportion of virally suppressed HIV-positive persons increased approximately 15%.

Conclusions: Using home HTC to identify SDCs and deliver universal ART could avert substantially more new HIV infections than home HTC alone, with a smaller number needed to treat to prevent new HIV infections. Scale-up of home HTC will not diminish the effectiveness of targeting SDCs for treatment. Increasing rates of couples' testing, disclosure, and linkage to care is an efficient way to increase the impact of home HTC interventions on HIV incidence.

Abstract [1]  Full-text [free] access  [2]

Editor’s notes: Delivering effective and efficient HIV prevention programmes to serodiscordant couples continues to be a challenge. The study used a dynamic stochastic agent–based network model to estimate the impact of universal antiretroviral therapy for serodiscordant couples. The authors examined the scaling up of antiretroviral therapy through home HIV testing and counselling in KwaZulu-Natal in South Africa and South-western Uganda. Data from South Africa and Uganda were used to compare three HIV programme scenarios. These included routine antiretroviral therapy delivery in the general population, routine antiretroviral therapy  delivery in the general population and home HIV testing and counselling campaigns, and home HIV testing and counselling and delivery of antiretroviral therapy to serodiscordant couples during home HIV testing and counselling campaigns.  The authors found that a combination of HIV prevention programmes that provide universal antiretroviral therapy for serodiscordant couples in the context of home HIV testing and counselling had more impact in reducing HIV incidence. The study demonstrated that home HIV testing and counselling and linkage to care HIV programmes can substantially reduce HIV incidence in South Africa and Uganda. This is a very interesting and well-designed modelling study which incorporates the effects of partnership dynamics in estimating the population level impact of HIV programmes.

HIV modelling [4]
Africa [5]
South Africa [6], Uganda [7]
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