Candidate for the Lee B. Lusted Student Prize Competition
Purpose: Recent evidence shows both antiretroviral therapy (ART) and oral pre-exposure prophylaxis (PrEP) are effective in reducing HIV transmission in heterosexual adults in resource-limited settings. The epidemiologic impact and cost-effectiveness of combined prevention approaches remain unclear.
Method: We develop a dynamic mathematical model of the adult South African HIV epidemic. We consider 3 disease stages: early (CD4 > 350 cells/µL), late (200-350 cells/µL) and advanced (< 200 cells/µL). Infectiousness is based on disease stage, number of sexual partnerships, ART, and PrEP. We assume ART reduces HIV transmission by 95% and PrEP by 60%. We model 2 ART strategies: scaling up access for those with CD4 counts ≤ 350 cells/µL (Guidelines) and for all identified HIV-infected individuals (Universal). PrEP strategies include use in the general population (General) and in high-risk individuals (Focused). We consider strategies where ART, PrEP, or both are scaled up to recruit 25%, 50%, 75% or 100% of remaining eligible individuals yearly. We assume annual costs of $150 for ART and $80 for PrEP. We measure infections averted, quality-adjusted life-years (QALY) gained and incremental cost-effectiveness ratios over 20 years.
Result: Scaling up ART to 50% of eligible individuals in South Africa averts 1,513,000 infections over 20 years using the Guidelines and 3,591,000 infections using a Universal strategy. Universal ART is more cost-effective than Guidelines ($310-$340/QALY gained compared with status quo). Expanding Guidelines ART to recruit 50% of those eligible yearly costs $410/QALY gained versus status quo, and this estimate is stable with higher coverage rates. General PrEP is costly and provides relatively small benefits beyond those of ART scale-up. Cost-effectiveness of General PrEP becomes less favorable when ART is given more widely ($1,050-$2,800/QALY gained). However, Focused PrEP is cost saving compared with the status quo and when added to any ART strategies except 75% or 100% Universal, where it is highly cost-effective.
Conclusion: Expanded ART coverage to individuals in early disease stages is more cost-effective than expansion of treatment per current guidelines. PrEP can be cost-saving if it can be delivered to individuals at increased risk of infection.