Preexposure Prophylaxis Indication Criteria Underidentify Black and Latinx Persons and Require Revision

Spillover benefit of pre-exposure prophylaxis for HIV prevention: evaluating the importance of effect modification using an agent-based model

We developed an agent-based model using a trial emulation approach to quantify effect measure modification of spillover effects of pre-exposure prophylaxis (PrEP) for HIV among men who have sex with men (MSM) in the Atlanta-Sandy Springs-Roswell metropolitan area, Georgia. PrEP may impact not only the individual prescribed, but also their partners and beyond, known as spillover. We simulated a two-stage randomised trial with eligible components (≥3 agents with ≥1 HIV+ agent) first randomised to intervention or control (no PrEP). Within intervention components, agents were randomised to PrEP with coverage of 70%, providing insight into a high PrEP coverage strategy. We evaluated effect modification by component-level characteristics and estimated spillover effects on HIV incidence using an extension of randomisation-based estimators. We observed an attenuation of the spillover effect when agents were in components with a higher prevalence of either drug use or bridging potential (if an agent acts as a mediator between ≥2 connected groups of agents). The estimated spillover effects were larger in magnitude among components with either higher HIV prevalence or greater density (number of existing partnerships compared to all possible partnerships). Consideration of effect modification is important when evaluating the spillover of PrEP among MSM.

What will it take to meet UNAIDS targets for preexposure prophylaxis users?

PURPOSE OF REVIEW

Preexposure prophylaxis (PrEP) is a critical strategy to curb new HIV infections globally. National and global targets have been set for people starting PrEP. However, global PrEP initiations fell short of UNAIDS 2020 targets, and reflection is needed on how we set and meet targets for PrEP use.

RECENT FINDINGS

Recent literature documents challenges to meeting ambitious goals for PrEP coverage in multiple phases of PrEP: PrEP initiations are limited by gaps in the identification of those who might benefit from PrEP. Conversely, getting PrEP to those who need it most is threatened by inaccurate risk perception and HIV and PrEP stigma. Once people are on PrEP, a substantial number discontinue PrEP in the first year (the 'PrEP Cliff'), a finding that is robust across groups of PrEP users (e.g., women, men who have sex with men, transwomen) and across global prevention settings. Further, PrEP inequities - by which we refer to utilization of PrEP in a specific group that is not commensurate with their epidemic risk - threaten the overall population benefit of PrEP because those at highest risk of acquiring HIV are not adequately protected.

SUMMARY

To realize global goals for PrEP utilization and impact, we must address multiple points of PrEP delivery programs that address not just PrEP starts, but also retention in PrEP and measurement and accountability to PrEP equity. We call for new approaches to better identify PrEP candidates, suggest additional research to address the known and consistent reasons for PrEP discontinuations, and advocate for metrics to measure and be accountable to PrEP equity.

Assessing the performance of international pre-exposure prophylaxis (PrEP) eligibility guidelines in a cohort of Chinese MSM, Beijing, China 2009 to 2016

INTRODUCTION

PrEP is a powerful HIV prevention tool, and locally relevant eligibility criteria are necessary to optimize the prevention impact of PrEP. We assessed performance of existing national and international PrEP eligibility criteria to predict future HIV seroconversion among MSM in Beijing, China.

METHODS

Participants were MSM aged ≥18 years who enrolled in a cohort study between July 2009 and March 2016. Participants completed HIV testing, syphilis testing, and a questionnaire on recent sexual health behaviours at each follow-up visit and were followed until HIV seroconversion or dropout. We assessed PrEP eligibility at the most recent follow-up visit prior to the final study visit. Participants were classified as indicated for PrEP (or not) based on criteria from guidelines from Europe, Korea, South Africa, Taiwan, the United Kingdom, United States and the World Health Organization. To compare guideline performance, we calculated sensitivity, specificity, Youden's Index (YI), Matthew's Correlation Coefficient (MCC), F1 scores and diagnostic odds ratios. For each guideline, performance measures were compared to random allocation of PrEP by randomly selecting a proportion of participants equal to the proportion indicated.

RESULTS

There were 287 (17∙3%) incident HIV seroconversions among 1663 MSM. The number of men indicated for PrEP from different guidelines ranged from 556 (33∙4%) to 1569 (94∙2%). Compared to random allocation, sensitivity of algorithms to predict seroconversion ranged from slightly worse (-4∙7%) to 30∙2% better than random. However, in absolute terms, none of the sensitivity values increased by more than 11% when compared to random allocation. For all guidelines, specificity was not meaningfully better than random allocation. No guidelines had high binary classification performance measures.

CONCLUSIONS

The performance of international indication guidelines in this sample was only slightly better than random allocation. Using such guidelines to screen out MSM self-identifying as interested in PrEP could lead to misallocation of resources and to good candidates for PrEP being denied access. For settings in which international guidelines perform poorly, alternative indication approaches should be considered.