Providing a conceptual framework for HIV prevention cascades and assessing feasibility of empirical measurement with data from east Zimbabwe: a case study

Geoffrey P Garnett,Timothy B Hallett,Albert Takaruza,James Hargreaves,Rebecca Rhead,Mitchel Warren,Constance Nyamukapa,Simon Gregson

doi:10.1016/s2352-3018(16)30039-x

Abstract

SummaryBackgroundThe HIV treatment cascade illustrates the steps required for successful treatment and is a powerful advocacy and monitoring tool. Similar cascades for people susceptible to infection could improve HIV prevention programming. We aim to show the feasibility of using cascade models to monitor prevention programmes.MethodsConceptual prevention cascades are described taking intervention-centric and client-centric perspectives to look at supply, demand, and efficacy of interventions. Data from two rounds of a population-based study in east Zimbabwe are used to derive the values of steps for cascades for voluntary medical male circumcision (VMMC) and for partner reduction or condom use driven by HIV testing and counselling (HTC).FindingsIn 2009 to 2011 the availability of circumcision services was negligible, but by 2012 to 2013 about a third of the population had access. However, where it was available only 12% of eligible men sought to be circumcised leading to an increase in circumcision prevalence from 3·1% to 6·9%. Of uninfected men, 85·3% did not perceive themselves to be at risk of acquiring HIV. The proportions of men and women tested for HIV increased from 27·5% to 56·6% and from 61·1% to 79·6%, respectively, with 30·4% of men tested self-reporting reduced sexual partner numbers and 12·8% reporting increased condom use.InterpretationPrevention cascades can be populated to inform HIV prevention programmes. In eastern Zimbabwe programmes need to provide greater access to circumcision services and the design and implementation of associated demand creation activities. Whereas, HTC services need to consider how to increase reductions in partner numbers or increased condom use or should not be considered as contributing to prevention services for the HIV-negative adults.FundingWellcome Trust and Bill & Melinda Gates Foundation.

Highlights

To halt the spread of HIV requires that efficacious treatment and preventive products or behaviours are used by those at risk
An HIV prevention cascade could be a powerful approach to complement the treatment cascade, by defining the different steps in successful implementation of prevention interventions, providing estimates of the proportions of populations lost at each step in implementation, demonstrating points at which inefficiencies occur, and providing a framework for planning further actions
For HIV testing and counselling (HTC), variables on adherence to sexual partner reduction and increased condom use were constructed from responses to the questions “After the HIV test, did you start having more or fewer sexual partners? / use condoms more or less than before?” We have estimates of the efficacy of voluntary medical male circumcision (VMMC) of 60%,16 but for partner reduction and condom use we have only reports about whether or not behaviour changed so have to assume by how much

Summary

Introduction

To halt the spread of HIV requires that efficacious treatment and preventive products or behaviours are used by those at risk. These products or behaviours are the direct mechanisms through which HIV prevention programmes exert their effect. These cascades attempt to include HIV prevention, but emphasise the steps of diagnosis, linkage to treatment, treatment initiation, and www.thelancet.com/hiv Vol 3 July 2016

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