Although large-scale provision of HIV pre-exposure prophylaxis (PrEP) is gaining momentum, no systematic method to evaluate or compare the effectiveness of different scale-up strategies in real-world settings exists. To date, estimating the effectiveness of PrEP has relied on clinical trials or mathematical models. We propose a novel and pragmatic metric to evaluate and compare programme effectiveness using routine implementation data. Using South African and Zambian PrEP guidelines, we provide two examples of how to consistently measure PrEP-programme effectiveness with routinely collected data. PrEP effectiveness should account for HIV seroconversion, the variable risk of HIV infection (seasons of risk) estimated with routine risk assessment at each clinic visit (when available), and the persistence of PrEP use. Three criteria should be met in order to be considered a successful outcome: first, a person who initiates PrEP must not seroconvert; second, there should be no more than one period at high risk of HIV infection during the follow-up period when not taking PrEP; and finally, an individual must continue to attend health-care visits or discontinue prophylaxis in consultation with a health-care provider within a specified follow-up period. The number of PrEP successes could then be compared with the total number of people initiating PrEP to establish a success ratio. This outcome is a useful and easily interpretable metric to monitor effectiveness of PrEP programmes with routinely collected clinical data and can be used in cost-effectiveness analyses. These measurements allow for comparisons of scale-up strategies for PrEP programmes and, if widely adopted, will allow comparative studies of different approaches for PrEP service delivery.

尽管大规模提供HIV暴露前预防（PrEP）的势头越来越大，但还没有系统的方法可以评估或比较现实环境中不同扩大规模策略的有效性。迄今为止，估计PrEP的有效性已依赖于临床试验或数学模型。我们提出了一种新颖实用的度量标准，用于使用常规执行数据评估和比较程序的有效性。使用南非和赞比亚的PrEP指南，我们提供了两个示例，说明如何使用常规收集的数据一致地衡量PrEP计划的有效性。PrEP的有效性应考虑到HIV的血清学转换，HIV感染的可变风险（风险季节），并通过每次诊所就诊（如果有）进行常规风险评估来估计，以及持久使用PrEP。为了被认为是成功的结果，应满足三个标准：首先，发起PrEP的人不得进行血清转化。第二，在不接受PrEP的随访期间，HIV感染的高风险不应超过一个时期。最后，个人必须在指定的随访期内继续与医疗保健提供者协商，参加医疗保健拜访或中止预防。然后可以将PrEP成功的次数与发起PrEP以建立成功率的总人数进行比较。该结果是一种有用且易于解释的指标，可通过常规收集的临床数据来监测PrEP计划的有效性，并可用于成本效益分析。这些测量结果可用于比较PrEP计划的放大策略，并且