Differentiating clearly positive from indeterminate results: A review of irreproducible HIV-1 PCR positive samples from South Africa's Early Infant Diagnosis Program, 2010-2015

Ahmad Haeri Mazanderani; Faith Moyo; Tendesayi Kufa; Jean Maritz; Gayle G Sherman

doi:10.1016/j.diagmicrobio.2018.02.019

Differentiating clearly positive from indeterminate results: A review of irreproducible HIV-1 PCR positive samples from South Africa's Early Infant Diagnosis Program, 2010-2015

Diagn Microbiol Infect Dis. 2018 Jul;91(3):248-255. doi: 10.1016/j.diagmicrobio.2018.02.019. Epub 2018 Mar 3.

Authors

Ahmad Haeri Mazanderani¹, Faith Moyo², Tendesayi Kufa³, Jean Maritz⁴, Gayle G Sherman⁵

Affiliations

¹ Centre for HIV & STIs, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; Department of Medical Virology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa. Electronic address: ahmadh@nicd.ac.za.
² Centre for HIV & STIs, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; Paediatric HIV Diagnostics Syndicate, Wits Health Consortium, Johannesburg, South Africa; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa.
³ Centre for HIV & STIs, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, South Africa.
⁴ PathCare Reference Laboratory and Stellenbosch University, Cape Town, South Africa.
⁵ Centre for HIV & STIs, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; Paediatric HIV Diagnostics Syndicate, Wits Health Consortium, Johannesburg, South Africa; Department of Paediatrics & Child Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.

PMID: 29655874
DOI: 10.1016/j.diagmicrobio.2018.02.019

Abstract

We describe the extent of and variables associated with irreproducible HIV-1 PCR positive results within South Africa's Early Infant Diagnosis (EID) program from 2010 to 2015 and propose criteria for differentiating indeterminate from clearly positive results using the COBAS® AmpliPrep/COBAS® TaqMan HIV-1 Qualitative Test version 2.0 (CAP/CTM Qual v2.0). Fourteen percent of specimens with an instrument-positive result that were repeat-tested yielded a negative result for which cycle threshold (Ct) proved to be the only predictive variable. A Ct <33.0 was found to be the most accurate threshold value for differentiating clearly positive from irreproducible cases, correctly predicting 96.8% of results. Among 70 patients with an irreproducible positive result linked to a follow up HIV-1 PCR test, 67 (95.7%) were negative and 3 (4.3%) were instrument-positive. Criteria differentiating clearly positive from indeterminate results need to be retained within EID services and infants with indeterminate results closely monitored and final HIV status determined.

Keywords: Diagnostic Accuracy; Early Infant Diagnosis; HIV-1 PCR; Indeterminate; Reproducibility.

MeSH terms

Child, Preschool
Early Diagnosis*
Female
HIV Infections / diagnosis*
HIV-1 / isolation & purification*
Humans
Infant
Male
Molecular Diagnostic Techniques / methods*
Polymerase Chain Reaction / methods*
Reproducibility of Results
Retrospective Studies
South Africa