Risk assessment and mitigation of hepatitis C virus RNA carryover contamination in a reflex testing algorithm

Area of Science:

• Clinical diagnostics
• Virology
• Public health laboratory science

Background:

• Active hepatitis C virus (HCV) diagnosis requires antibody and RNA confirmation.
• Current practices often involve two sample collections, hindering timely diagnosis and care.
• Centers for Disease Control and Prevention (CDC) recommends reflexive RNA testing for improved linkage to care.

Purpose of the Study:

• To evaluate the false positivity rate of reflexive HCV RNA testing.
• To assess the effectiveness of a risk mitigation strategy for low-positive HCV RNA results.
• To support the wider implementation of reflexive RNA testing for HCV diagnosis.

Main Methods:

• Retrospective analysis of HCV RNA results from a reference laboratory.
• Comparison of false positive rates before and after implementing a medical director review for low-positive (<1,000 IU/mL) results.
• Adjudication of low-positive results based on clinical history and redraw results.

Main Results:

• The pre-intervention false positive rate was 0.44%.
• Post-intervention, the false positive rate significantly decreased to 0.14% (P = 0.008).
• True-positive results had significantly higher median viral loads compared to false-positive or unknown results.

Conclusions:

• Reflexive RNA testing is a viable strategy to improve HCV diagnosis and linkage to care.
• A risk mitigation strategy involving medical director review effectively reduces false positives in reflexive HCV RNA testing.
• The study supports the broader adoption of reflexive testing algorithms in clinical laboratories.