Optimizing the Elecsys HCV assay threshold to improve hepatitis C diagnosis algorithm and reduce healthcare costs by minimizing supplementary tests.

PURPOSE

Viral hepatitis remains a leading cause of infectious mortality worldwide. This study aimed to improve the serological screening process by reducing unnecessary testing and healthcare costs by optimizing the assay threshold.

METHODS

Three methods (Elecsys Anti-HCV II, Alinity s Anti-HCV and Ortho HCV 3.0) were compared against a composite gold standard on 260 samples. The best-performing was used to establish an optimal S/CO cut-off for our screening method (Elecsys Anti-HCV II), predictive of true-positivity. A confirmatory assay (Vidas anti-HCV) was used to differentiate true from false positives. A simulation of the use of this cut-off was conducted on a retrospective cohort to assess its effectiveness in terms of diagnosis and healthcare costs.

RESULTS

The Alinity s Anti-HCV II assay showed the highest sensitivity (100%) and specificity (98.2%). This assay was used to establish the cut-off threshold for our method. The best Youden's index was obtained with a value of 17.8 (sensitivity (95.6%), specificity (96.4%)). In a retrospective cohort of 667 patients with a positive initial HCV screening, 124 had an S/CO ratio of ≤ 17.8. Of these, Vidas anti-HCV confirmed 105 negative results (15.74% of the cohort), eliminating the need for PCR testing for these patients. The estimated theoretical savings for a 7-month assessment period is € 7186,2.

CONCLUSIONS

An S/CO cut-off of 17.8 was established for the Elecsys Anti-HCV II assay, accurately predicting true positives in 97% of cases and reduced the need for unnecessary PCR confirmatory testing, resulting in cost savings.