HIV暴露前預防投藥策略對台灣男男間性行為傳染愛滋疫情的防治效果:數理模式研究

Abstract

背景： 台灣目前每年持續新增約2000位男男間性行為相關HIV診斷病例，逆轉HIV疫情亟需更有效的防治策略。世界衛生組織在2015年正式建議各國將HIV暴露前預防用藥 (HIV Pre-Exposure Prophylaxis, PrEP) 列入防治措施。PROUD (2015) 與IPERGAY (2015) 研究皆顯示HIV暴露前預防用藥能夠降低86% 的HIV感染風險，效果為先前iPrEX (2010) 研究報告的兩倍。因此，先前採用iPrEX資料的數理模式研究低估HIV暴露前預防用藥的成效。本研究目的為評估在台灣擴大實施HIV暴露前預防用藥對台灣男男間性行為傳染HIV疫情的防治效果，並計算其成本效益。 方法： 本研究利用最新HIV疫情監測及HIV病人就醫率資料，更新先前的HIV疫情傳播動態數理模式相關參數，並將詳細的年齡結構、危險族群結構及人口學變項納入考量。我們以數理模擬方式評估：擴大實施HIV暴露前預防用藥、擴大實施HIV篩檢與治療 (Test-and-Treat) 措施、以及兩者合併的防治策略，對於消除台灣男男間性行為者HIV疫情 (依世界衛生組織定義為發生率低於每年千分之一) 的效果，以及擴大實施HIV暴露前預防投藥的成本效益。 結果： HIV暴露前預防用藥覆蓋率若能提升到 50% 以上，即可在2025年之前達成消除HIV疫情的目標。擴大HIV篩檢至每年一次且 90% 新案於診斷後立即開始抗病毒藥物治療能在2022年之前達成消除HIV疫情的目標。Test-and-Treat與PrEP具有加乘效果：針對15-44歲高風險群，PrEP覆蓋率僅需提升到25%，配合兩年一次HIV篩檢且 75% 新案於診斷後立即開始抗病毒藥物治療，亦能在2030年之前達成HIV疫情消除。在台灣擴大實施HIV暴露前預防用藥可大幅度節省醫療成本：若針對15-44歲高風險群，提供25% PrEP覆蓋率，則每投資一元於PrEP，即可節省11.2元醫療費用。敏感度分析顯示：PrEP藥物的 保護力 (86% vs. 44%) 為是否能消除HIV疫情的關鍵因素；而PrEP的使用方式 (event-driven vs. daily) 以及是否針對高風險族群提供則是影響PrEP成本效益的關鍵因素。 結論： HIV暴露前預防用藥是極有效的HIV防治策略，而且可大幅度節省醫療成本。同步擴大實施HIV暴露前預防用藥及HIV篩檢與治療策略，可望在10年內消除台灣男男間性行為傳播HIV疫情。

Background: Men who have sex with men (MSM) are disproportionally affected by the HIV epidemic. There are now around 2,000 new MSM-HIV cases annually in Taiwan, under current HIV testing rate and antiretroviral therapy (ART) coverage. More effective strategy is urgently required to control the HIV epidemic in this vulnerable population. Both PROUD (2015) and IPERGAY (2015) studies demonstrated an 86% efficacy of PrEP, twice better than the 44% efficacy reported by the earlier iPrEX (2010) study. Therefore, previous modeling studies, which were based on iPrEX data, might under-estimated the actual impact of scaling-up PrEP among MSM. We aimed to evaluate the impact and cost-effectiveness of scaling-up PrEP on the MSM-HIV epidemic in Taiwan. Methods: We used the newest HIV surveillance and follow-up data to calibrate our HIV dynamic transmission model for MSM in Taiwan. We simulated the impact of scaling-up PrEP, Test-and-Treat, or both, on the future trajectory of HIV epidemic in MSM. We evaluate whether scaling-up PrEP will eliminate the MSM-HIV epidemic (incidence lower than 1/1000 per year, World Health Organization) in Taiwan, and whether such intervention is cost-effective. Findings: Scaling-up PrEP to 50% coverage or more will eliminate HIV among MSM by 2025. Annual HIV testing followed by immediate ART after HIV diagnosis in 90% of new cases will eliminate HIV epidemic by 2022. PrEP and Test-and-Treat are synergistic: if we target 15- to 44-year-old high-risk group, then 25% PrEP coverage in this group is sufficient to eliminate HIV epidemic by 2030 under biannual HIV testing followed by immediate ART in 75% of new cases. Cost analysis shows that NT$11.2 medical costs can be saved for every NT$1 spent on PrEP. Sensitivity analyses showed that efficacy of PrEP drug is the key factor for its role in HIV elimination, while method of administration (event-driven) and prioritization (high-risk group) are the key factors for its cost-effectiveness. Interpretation: PrEP is a highly effective HIV prevention strategy, and is cost-saving. Our results support the simultaneous expansion of both PrEP and HIV “Test-and-Treat” in Taiwan, with the aim to eliminate HIV epidemic among MSM in the next 10 years.