HIV Infection May Impact Sensitivity of Rapid Diagnostic Tests for HCV

By Marilynn Larkin

July 14, 2020

NEW YORK (Reuters Health) - Hepatitis C virus (HCV) rapid diagnostic tests (RDTs) had variable sensitivity in patients with HIV, in a multinational retrospective study.

The varied sensitivity "didn't seem to be driven by compromised immune status due to HIV, but rather the status of HCV infection, i.e. acute (actively infected) or cleared (undetectable concentrations of HCV RNA in blood)." said Dr. Beatrice Vetter of the Foundation for Innovative New Diagnostics in Geneva.

Reassuringly, "test sensitivity was acceptable for most tests in cases of acute HCV infection - i.e., in patients who are in need of treatment," she said.

As reported In the Journal of Infectious Diseases, two lots of 13 RDTs were evaluated at three laboratories using archived plasma samples from four countries (Nigeria, Georgia, Cambodia, Belgium). Sensitivity and specificity were assessed in HIV-infected and HIV-uninfected populations. Beyond HIV and HCV treatment status, no additional information on the sample donors was collected.

In 384 HIV-uninfected samples, the majority of RDTs had 98% or more sensitivity in one or both lots, and most RDTs had a specificity close to 99%.

By contrast, in 264 HIV-infected samples, specificity remained high, but sensitivity was markedly lower than in HIV uninfected samples; only one RDT reached >95%. The majority of HIV-infected samples for which sensitivity was low did not have detectable HCV viral load/core antigen.

Inter-reader variability, lot-to-lot variability and the rate of invalid runs were low for all RDTs (<2%).

The authors conclude, "HCV RDTs should be evaluated in the intended target population, as sensitivity can be impacted by population factors such as HIV status."

Dr. Vetter said the findings are "likely to be applicable to all populations, regardless of high- or low- and middle-income countries. Further research is needed to gain an improved understanding of the level of antibody titers in past and present HCV infections in order to better interpret the performance of critically needed diagnostic tests."

Dr. Kagya Amoako, Director of the Biomaterials and Medical Device Innovation Laboratory at the University of New Haven in Connecticut, commented by email to Reuters Health, "The authors make some reasonable conclusions in that T cells, like CD4 cells, which fight off pathogens by helping with antibody production, die en masse via pyroptosis and apoptosis with HIV infection."

"When these cells die, the body's ability to produce antibodies to other pathogens such as HCV can diminish," he said. "So, it makes sense that they see decreased sensitivity of RDTs for serum hepatitis C antibodies in HIV-infected patient populations."

"Their conclusions may also be important to the current COVID-19 pandemic regarding issues of false-negative test outcomes," he noted. Current coronavirus diagnostic tests may have an error rate up to 15%, depending on the kind of test.

"Could this decrease in diagnostic kit sensitivity be attributable to more than just poorly designed detection platforms and outcomes algorithms?" he wondered. "To what degree could some underlying viral-disease conditions influence sensitivity? Could antibody levels in COVID-19 patients be low and evade detection in immunodeficient patients (compared with) patients without underlying conditions that compromise immunoresponse?"

"To the infectious disease community, these are important questions that require further investigation," Dr. Amoako concluded.

SOURCE: https://bit.ly/2OpihGs Journal of Infectious Diseases, online July 2, 2020.

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