Optimizing HIV testing services in sub-Saharan Africa: Cost and performance of verification testing with HIV self-tests and tests for triage
File(s)
Author(s)
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.
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.
Date Issued
2019-03-01
Date Acceptance
2019-01-02
Citation
Journal of the International AIDS Society, 2019, 22 (S1)
ISSN
1758-2652
Publisher
International AIDS Society
Journal / Book Title
Journal of the International AIDS Society
Volume
22
Issue
S1
Copyright Statement
©2019 World Health Organization; licensed by IAS. This is an open access article distributed under the terms of the Creative Commons Attribution IGOLicense https://creativecommons.org/licenses/by/3.0/igo/legalcode which permits unrestricted use, distribution and reproduction in any medium, provided that theoriginal work is properly cited. In any reproduction of this article there should not be any suggestion that WHO or the article endorse any specific organization orproducts. The use of the WHO logo is not permitted. This notice should be preserved along with the article’s URL.
Sponsor
UNAIDS
Bill & Melinda Gates Foundation
Medical Research Council
Medical Research Council (MRC)
Grant Number
2017/778519
OPP1190661
MR/K010174/1B
MR/R015600/1
Subjects
Science & Technology
Life Sciences & Biomedicine
Immunology
Infectious Diseases
HIV
HIV testing
HIV self-testing
Retesting
ART initiation
Quality
HIV
ART initiation
HIV self-testing
HIV testing
Quality
Retesting
1199 Other Medical and Health Sciences
Publication Status
Published
Article Number
e25237
Date Publish Online
2019-03-25