Modeling the impact of early HIV treatment on the HIV epidemic in South Africa

[摘要] ENGLISH SUMMARY: Amajor international randomized clinical trial fromStrategic Timing of AntiRetroviral Treatment(START) has found that HIV-infected individuals have a considerably lower risk of developingAIDS if they start taking antiretroviral drugs sooner. According to the guidelinespre-released in September 2015, the World Health Organization (WHO) recommends thatART should be initiated in all adults living with HIV at any CD4 cell count. Following previousWHO recommendations, many governments have steadily changed antiretroviral therapy(ART) guidelines over the last decade. South Africa has revised ART guidelines to increaseaccess to treatment to 500 CD4 cell counts/mm3 or lesswith effect fromthe 1st January 2015.In ART programs, some individuals who initiate ART either fail treatment and switch regimenor dropout from ART, which might undermine the outcomes of ART programs. Thus,in the thesis, we formulated and analyzed new mathematicalmodels that assess the impactof treatment failure and dropout on ART outcomes and associated costs. The models weconsidered consist of partial differential equations that are structured by time since infectionand time since ART roll out. Our results confirmthat early initiation of ART contributes to a steep decline in the number of new HIV infections and HIV deaths, but also show thatthe benefit of ART might be limited due to the impact of dropout and treatment failure. Despitethe uncertainties associatedwith some of themodels' parameters,such as ART inducedsexual behavioral change and ART access rate, with the current trend of ART access rateour simulations show that HIV elimination is not possibly achievable within a decade. Toachieve HIV elimination soon, ART access ratemust substantially increase, and the dropoutand treatment failure rates must substantially reduce. If individuals keep dropping out ofHIV treatment at current rates and they engage in risky sexual contact, HIV incidence willincrease unless other intervention measures are taken. Consequently, the burden on theannual cost of providing ART will continue to increase.

[发布机构] Stellenbosch University