The evaluation of point of care testing and dried blood spots to assess diagnostic accuracy of HCV infection as part of Sero-Molecular surveillance in people most-at-risk for hepatitis C virus
Date
2018
Authors
Gaelejwe, Lucinda Rebaone
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
There are gaps in the knowledge of the burden of HCV infection in high-risk communities in South Africa. We evaluated HCV POCT and DBS samples for diagnostic accuracy as potential strategies for access to healthcare services and to determine the sero-molecular epidemiology of HCV in high-risk groups.
This study formed a sub-study on a major study entitled “The viral hepatitis C initiative for most at risk populations in South Africa” in collaboration with TB HIV Care (THC), Anova Health Institute (Anova), OUT Wellbeing (OUT), the Division of Hepatology at the University of Cape Town (UCT) and the National Institute of Communicable Diseases (NICD). The study was based on the integrated services of existing HIV prevention programmes for men who have sex with men (MSM), sex workers (SW) and people who use drugs, including people who inject drugs (PWUDs/PWIDs) across seven South African cities. This is a first study in South Africa to provide information on hepatitis C prevalence data among these key populations and assessing the usefulness and validity of point of care hepatitis C testing in the South African context.
The study was conducted from August 2016 - October 2017, in seven cities in South Africa and enrolled a total of 3509 participants. HCV POCT was used for diagnostic testing at research sites. A total of 532 PWUDs/PWIDs, 66 MSM and 115 SWs. Samples with positive HCV tests were sent to the NICD laboratory for confirmation of POCT results using the automated Architect i system for anti-HCV testing. All antibody positive samples were followed up with viral load testing on the automated COBAS® Ampliprep/TaqMan® and genotyping using the Versant HCV genotyping 2.0 Assay. Furthermore, from Cape Town sites, DBS and plasma paired specimens were collected to assess the accuracy of POCT testing and to assess the accuracy of viral testing on DBS. HCV antibody was tested on both DBS and plasma paired samples on the Architect i system. HCV viral loads were tested on paired plasma and DBS samples using the automated COBAS® Ampliprep/TaqMan® 48 analyser. The STARD approach was used in reporting the accuracy of POCT. Sensitivity and specificity, positive predictive and negative predictive values were calculated for antibody tests. For viral load comparison between DBS and plasma, agreement of methods was determined by Linear Regression and Bland Altman plot.
At the end of the study, 713 plasma samples and 240 DBS were received at the NICD laboratory. Plasma samples (N=705) and DBS (N=239) were tested. HCV POCT testing had a sensitivity of 98.5% and specificity of 97.6%. DBS testing had a sensitivity of 96.3% and specificity of 97.4%. The linear regression was R2=0.918 and there was no difference between methods using the Bland Altman analysis. Viral load on plasma ranged from 1.2 log IU/ml to 7.7 log IU/ml. The prevalent genotypes were genotype 1a (73.93%), 3a (14.79%), and 3 (3.51%).
HCV POCT can be used with a high degree accuracy. DBS can be used as an alternative sample matrix for HCV serology and RNA testing among high-risk groups. These tools are recommend in the South Africa setting to provide access to diagnosis and treatment as part of the WHO 2030 HCV elimination strategy.
Description
A dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Medicine to the Faculty of Health Science, University of the Witwatersrand, Johannesburg, 2018
Keywords
Citation
Gaelejwe, Lucinda Rebaone (2018) The evaluation of point of care testing and dried blood spots to assess diagnostic accuracy of HCV infection as part of Sero-Molecular surveillance in people most-at-risk for hepatitis C virus, University of the Witwatersrand, Johannesburg, https://hdl.handle.net/10539/27723