Optimizing HIV testing services in sub-Saharan Africa: Cost and performance of verification testing with HIV self-tests and tests for triage

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Title: Optimizing HIV testing services in sub-Saharan Africa: Cost and performance of verification testing with HIV self-tests and tests for triage
Authors: Eaton, J
Terris-Prestholt, F
Cambiano, V
Sands, A
Baggaley, R
Hatzold, K
Corbett, E
Kalua, T
Jahn, A
Johnson, CC
Item Type: Journal Article
Abstract: Introduction:Strategies employinga single rapid diagnostic test (RDT) such as HIV self-testing (HIVST)or ‘test for triage’ (T4T)areproposed to increase HIV testing programme impact.Current guidelines recommend serial testing with two or three RDTs for HIV diagnosis, followed by retestingwith the same algorithmto verify HIV-positive statusbefore anti-retroviral therapy (ART) initiation. We investigated whether clientspresenting to HTS following a single reactive RDTmust undergo thediagnostic algorithm twice to diagnose and verify HIV-positive status, or whether a diagnosis with the setting-specific algorithm is adequate for ART initiation.Methods: We calculated (1)expected number of false-positive (FP) misclassifications per 10,000 HIV negative persons tested,(2)positive predictive value (PPV) of the overall HIV testingstrategy compared to WHO recommended PPV ≥99%, and (3) expected cost per FPmisclassified person identified by additional verification testingin a typical low-/middle-income setting, compared to the expected lifetime ART cost of $3000. Scenarios considered were: 10% prevalence using two serial RDTsfor diagnosis,1% prevalence using three serial RDTs,and calibrationusing programmatic data from Malawi in 2017where theproportion of people testing HIV positive in facilities was 4%. Results: In the 10% HIV prevalence settingwith a triage test, the expected number ofFP misclassifications was0.86 per 10,000 tested without verification testing and the PPV was 99.9%. In the 1% prevalence setting, expected FP misclassifications were 0.19 with 99.8% PPV, and in the Malawi 2017 calibrated setting the expected misclassifications were 0.08 with 99.98% PPV. The cost per FP identified by verification testing was $5,879, $3,770, and $24,259, respectively. Results were sensitive to assumptions about accuracy of self-reported reactive results and whether reactive triage test results influenced biased interpretation of subsequent RDT results by the HTS provider. Conclusions: Diagnosis with the full algorithm following presentation with a reactive triage test is expected to achieve PPV above the 99% threshold. Continuingverification testing prior to ART initiation remains recommended, but HIV testing strategies involving HIVST and T4Tmay provide opportunities to maintain quality while increasing efficiency as part of broader restructuring of HIV testing service delivery.
Issue Date: 1-Mar-2019
Date of Acceptance: 2-Jan-2019
URI: http://hdl.handle.net/10044/1/66961
ISSN: 1758-2652
Publisher: International AIDS Society
Journal / Book Title: Journal of the International AIDS Society
Copyright Statement: This paper is embargoed until publication. Once published it will be available fully open access.
Sponsor/Funder: UNAIDS
Bill & Melinda Gates Foundation
Medical Research Council (MRC)
Medical Research Council
Funder's Grant Number: 2017/778519
Keywords: 1199 Other Medical And Health Sciences
Publication Status: Accepted
Embargo Date: publication subject to indefinite embargo
Appears in Collections:Faculty of Medicine
Epidemiology, Public Health and Primary Care

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