Evaluation of the use of a combined HCV antigen/antibody assay in routine laboratory practice

Performance of Elecsys® HCV Duo Immunoassay for Diagnosis and Assessment of Treatment Response in HCV Patients with or without HIV Infection

BACKGROUND/OBJECTIVES

The Elecsys® HCV Duo immunoassay (Roche Diagnostics International Ltd., Rotkreuz, Switzerland) detects both antibodies to hepatitis C virus (anti-HCV) and HCV core antigen (HCV-Ag) and has shown excellent diagnostic performance in blood donor samples. We aim to validate its use for diagnosing chronic HCV infection and assessing sustained virological response (SVR) post-direct-acting antivirals (DAAs) in patients with or without HIV infection.

METHODS

Blood samples from 100 healthy controls, as well as 64 HCV mono-infection and 136 HCV-HIV coinfections, were collected before and 12-24 weeks after DAAs. The assay performance for determining active infection at baseline and SVR was compared with HCV RNA.

RESULTS

Overall, 156 (78.0%) of HCV-infected patients had HCV genotype 1, and the SVR rate was 96.5%. The sensitivity, specificity, and area under the ROC curve (AUROC) for HCV diagnosis at baseline were 99.50% (95% confidence interval [CI], 96.82-99.97%), 100% (95%CI, 95.39-100%), and 0.998 (95%CI, 0.992-1.003), respectively. The corresponding results for HCV-Ag in determining SVR were 57.14% (95%CI, 20.24-88.19%), 97.41% (95%CI, 93.73-99.04%), and 0.773 (95%CI, 0.543-1.003), respectively. The assay also exhibited comparable sensitivity and specificity between HCV mono- and coinfection.

CONCLUSIONS

Our study showed that the Elecsys® HCV Duo immunoassay effectively diagnosed HCV infection, regardless of HIV status, making it suitable for managing high-risk populations in resource-limited settings.

Metaanálisis de la validez y el desempeño de las pruebas de tamización del virus de la hepatitis C en bancos de sangre, 2000-2018

Este estudio evaluó la validez y desempeño del inmunodiagnóstico del virus de la hepatitis C (VHC), con base en estudios publicados en la literatura científica mundial. Se diseñó y validó un protocolo de búsqueda y selección de investigaciones en las fases de la guía PRISMA, se analizaron los parámetros de sensibilidad, especificidad, cocientes de probabilidad, razón de odds y curva ROC, en MetaDisc. Se tamizaron 4602 estudios, de los cuales sólo 545 se realizaron en bancos de sangre y 18 evaluaron la validez diagnóstica de las pruebas para el VHC. La mayoría de los estudios fueron de Europa y Asia, con un 78 % basados en determinación de anticuerpos. Los estudios con detección de anticuerpos se realizaron en 21 483 donantes sanos y 3 145 infectados en quienes se halló una sensibilidad de 97,8 % (IC 95 % = 97,3 - 98,2), especificidad 99,0 % (IC 95 % = 98,9 - 99,2), cociente de probabilidad positivo 75,4 (IC 95 % = 27,2 - 209,2) y negativo de 0,02 (IC 95 % = 0,01 - 0,07) y área bajo la curva de 99,8 %. Se concluye que la detección de anticuerpos presenta excelente validez, desempeño y utilidad diagnóstica para la detección del VHC en donantes de sangre y población general.

Who to test and how to test for chronic hepatitis C infection - 2016 WHO testing guidance for low- and middle-income countries

Testing and diagnosis of hepatitis C virus (HCV) infection is the gateway for access to both treatment and prevention services, and crucial for an effective hepatitis epidemic response. In contrast to HIV, a systematic approach to hepatitis C testing has been fragmented and limited to a few countries, and there remains a large burden of undiagnosed cases globally. Key challenges in the current hepatitis testing response, include lack of simple, reliable, and low cost diagnostic tests, laboratory capacity, and testing facilities; inadequate data to guide country-specific hepatitis testing approaches and who to test; stigmatization and social marginalization of some groups with or at risk of viral hepatitis; and lack of international or national guidelines on hepatitis testing for resource-limited settings. New tools to support the hepatitis global response include the 2016 Global Hepatitis Health Sector Strategy which include targets for testing and diagnosis, and World Health Organization (WHO) 2016 hepatitis testing guidelines for adults, adolescents, and children in low- and middle-income countries. The testing guidance complements recent published WHO guidance on the prevention, care and treatment of chronic hepatitis C and hepatitis B infection. These testing guidelines outline the public health approach to strengthening and expanding current testing practices for HCV and HBV and address what serological and virological assays to use, and who to test, as well as interventions to promote linkage to prevention and care after testing. They are intended for use across all age groups and populations. See boxes for key recommendations. Future directions and innovations in viral hepatitis testing include use of point-of-care assays for nucleic acid testing (NAT) and core antigen; validation of dried blood spots specimens with different commercial serological and NAT assays; multiplex and polyvalent platforms for integrated testing of HIV, HBV and HCV; and potential for self-testing.

New tools in HCV diagnosis, in light of the enhanced awareness and the new drugs for treatment: SMARTube and stimmunology

With improved HCV therapy, challenges regarding HCV diagnosis, such as seronegative window period, false positive readings, and differentiation between recent, chronic, and resolved infections, are of increasing importance. To address these challenges an innovative device—SMARTube HIV & HCV—was used. Blood samples were tested for anti-HCV antibodies before and after incubation in the SMARTube, which promotes the in vitro stimulation of in vivo HCV primed lymphocytes, thus enhancing levels of anti-HCV antibodies. Comparing antibody levels, in concordant samples before and after SMARTube, yielded the Stimulation Index (SI). Among 5888 fresh blood samples, from various populations and regions worldwide, 641 were seropositive using plasma, while SMARTube processing (yielding enriched plasma, termed SMARTplasma) enabled diagnosis of 10 additional carriers in high-risk cohorts, that is, earlier detection. Using SMARTplasma eliminated all false positive results, using the current assays. In addition we show that SI calculation may serve as an important tool for differentiating between those who recently seroconverted, carriers of long-term infection, and those who have cleared the virus. SMARTube and the SI could lead to better, more informative diagnosis of HCV infections and play an important role in changing the way we treat both the infected individuals and the epidemic as a whole.