POC HCV RNA Testing Key to Achieving National Viral Elimination Goals

The Xpert HCV Viral Load test (Cepheid, Sunnyvale, Calif.) for hepatitis C virus (HCV) has good accuracy for detecting viral RNA using whole blood from a finger stick, according to a study published in the July issue of The Lancet Gastroenterology & Hepatology. The authors say this is the first published evaluation of an assay for HCV RNA detection using finger-stick whole-blood collection in a clinical setting and is an important step towards enabling point-of-care (POC), HCV RNA testing, particularly in high-risk settings.

The lack of validated POC tests is a known challenge to improving HCV diagnosis and linkage to treatment. POC HCV RNA testing offers a two-fold advantage over antibody testing in that it an enable diagnosis of active infection (versus previous exposure with antibody testing) and they can do so in a single visit.

"Sensitive HCV RNA testing of whole blood collected by finger-stick is particularly appropriate for populations with a high prevalence of HCV infection," write the authors led by Jason Grebely, Ph.D., from the Kirby Institute in Australia. "First, people who inject drugs often have poor venous access as a result of injecting, making the collection of blood via venepuncture very difficult … Second, data have shown that on-site HCV testing with integrated care improves linkage to HCV care."

The Lancet study evaluated testing conducted on 210 participants at five sites with high-risk populations (drug and homeless service programs). The study compared the performance of the Xpert HCV Viral Load test for HCV RNA detection using both venepuncture and finger-stick collection to the Abbott RealTime HCV Viral Load assay (gold standard).

Final analysis included data from the 150 participants that had viral load testing results for all three assays tested. Sensitivity of the Xpert HCV Viral Load assay for HCV RNA detection in plasma collected by venipuncture was 100% and specificity was 99%. Sensitivity of the assay for HCV RNA detection in samples collected by finger-stick was 95.5% and specificity was 98.1%. The authors say that one percent of samples tested did not provide a result on the Xpert HCV Viral Load assay because of low sample volume in the cartridge.

"The manufacturer of the assay is using this study to optimize the assay so that the results of the assay will be provided in 60 minutes, which should lead to the development of a commercially available Xpert HCV Viral Load test for HCV RNA detection in capillary whole blood collected by finger-stick," writes Gebely and colleagues.

Takeaway: This first validation of a POC HCV RNA test is an important step to increasing one-step testing and linkage to care, particularly for high-risk populations, and achieving a national screening strategy.


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