Department of Infectious Disease Epidemiology, Imperial College London, London, UK; Division of Infectious Diseases and Global Public Health, University of California San Diego, San Diego, CA, USA.
Investigaciones Médicas en Salud (INMENSA), Lima, Peru.
Lancet Public Health. 2019 Mar;4(3):e127-e136. doi: 10.1016/S2468-2667(18)30236-6. Epub 2019 Jan 23.
HIV incidence remains high among transgender women in Lima, Peru, most of whom report sex work. On the basis of a stakeholder analysis and health system capacity assessment, we designed a mathematical model to guide HIV programmatic planning among transgender women sex workers (TWSW) in Lima.
Using a deterministic compartmental model, we modelled HIV transmission among TWSW, their stable partners, and their clients to estimate the impact and cost-effectiveness of combinations of interventions compared with the standard of care on reducing HIV incidence over a 10-year period. We simulated HIV transmission accounting for differences in sexual positioning in anal intercourse and condom use by partner type and fitted the model to HIV surveillance data using Latin hypercube sampling. The interventions we considered were 15% relative increase in condom use with clients and 10% relative increase with stable partners; increase in antiretroviral treatment (ART) coverage at CD4 count lower than 500 cells per mm and greater than or equal to 500 cells per mm; and 15% pre-exposure prophylaxis (PrEP) coverage using generic and branded formulations. We considered a basic scenario accounting for current limitations in the Peruvian HIV services and an enhanced scenario assuming achievement of the UNAIDS 90-90-90 targets and general improvements in HIV services. The 50 best fits according to log-likelihood were used to give the minimum and maximum values of intervention effect for each combination. We used disability-adjusted life-years (DALYs) to measure the negative health outcomes associated with HIV infection that could be averted through the interventions investigated and calculated incremental cost-effectiveness ratios to compare their cost-effectiveness.
Under the basic scenario, combining the four interventions of increasing condom use with clients and stable partners, extending ART to people with CD4 count greater than or equal to 500 cells per mm, and 15% PrEP coverage with generic drugs would avert 47% (range 27-51) of new infections in TWSW, their clients, and their stable partners over 10 years, with an incremental cost-effectiveness ratio of US$509 per DALY averted. Under the enhanced scenario, this strategy would avert 61% (44-64) of new infections among this population with an incremental cost-effectiveness ratio of $1003 per DALY averted. Under both scenarios, implementation of this strategy approaches or surpasses the 50% incidence reduction goal and would represent a cost-effective use of country resources if generic PrEP drugs are used. The total cost of implementing this strategy under the enhanced scenario would be approximately $1·2 million per year over 10 years, corresponding to 10% of the current Global Fund's yearly contribution in Peru.
Investments in HIV services among TWSW in Lima would be cost-effective, even under stringent cost-effectiveness criteria when accounting for setting-specific resource constraints. Notable improvements in HIV testing rates, innovative interventions to increase condom use, and reduced PrEP costs will be key to achieving the 50% incidence reduction goal. Modelling studies incorporating stakeholders' perspectives and health system assessments can bring added value to HIV policy making.
National Institutes of Health.
在秘鲁利马，跨性别女性的 HIV 发病率仍然很高，其中大多数人报告从事性工作。在利益相关者分析和卫生系统能力评估的基础上，我们设计了一个数学模型，以指导利马跨性别女性性工作者（TWSW）中的 HIV 规划。
我们使用确定性隔室模型来模拟 TWSW、其稳定伴侣和客户之间的 HIV 传播，以估计与标准护理相比，在 10 年内降低 HIV 发病率的各种干预措施的影响和成本效益。我们模拟了 HIV 传播，考虑了肛交中不同的性体位以及与伴侣类型有关的避孕套使用情况的差异，并使用拉丁超立方体抽样法将模型拟合到 HIV 监测数据中。我们考虑的干预措施包括：客户使用避孕套的相对增加 15%，稳定伴侣使用避孕套的相对增加 10%；CD4 计数低于 500 个细胞/毫米和大于或等于 500 个细胞/毫米时，增加抗逆转录病毒治疗（ART）覆盖率；使用通用和品牌制剂的 15%事前预防（PrEP）覆盖率。我们考虑了一个基本方案，该方案考虑了秘鲁 HIV 服务的当前限制，以及一个增强方案，假设实现了联合国艾滋病规划署 90-90-90 目标和一般改善的 HIV 服务。根据对数似然，使用 50 个最佳拟合来给出每种组合的干预效果的最小和最大值。我们使用残疾调整生命年（DALY）来衡量与 HIV 感染相关的负面健康结果，这些结果可以通过调查的干预措施来避免，并计算增量成本效益比来比较它们的成本效益。
在基本方案下，将增加与客户和稳定伴侣使用避孕套、将 ART 扩展到 CD4 计数大于或等于 500 个细胞/毫米的人群以及使用通用药物的 15%PrEP 覆盖率相结合，将在 10 年内避免 TWSW、其客户和稳定伴侣中 47%（27-51）的新感染，增量成本效益比为每避免一个 DALY 花费 509 美元。在增强方案下，这一策略将避免该人群中 61%（44-64）的新感染，增量成本效益比为每避免一个 DALY 花费 1003 美元。在这两种情况下，实施这一策略都接近或超过了 50%的发病率降低目标，如果使用通用 PrEP 药物，将代表对国家资源的有效利用。在增强方案下，实施这一策略的总成本将在 10 年内每年约为 120 万美元，相当于全球基金在秘鲁每年捐款的 10%。
在考虑到特定于环境的资源限制的严格成本效益标准下，对利马 TWSW 进行 HIV 服务投资将具有成本效益。显著提高 HIV 检测率、创新的增加避孕套使用的干预措施以及降低 PrEP 成本将是实现 50%发病率降低目标的关键。将利益相关者观点和卫生系统评估纳入模型的研究可以为 HIV 政策制定带来附加值。
美国国立卫生研究院。
