Study Aims and Results
The authors conducted a study to analyze commercial hepatitis C genotype/subtype assays to understand the cost-effectiveness of potential errors in genotype/subtype assays. The study was conducted between March and September 2015.
It is estimated that approximately 10% of the current assays incorrectly classify genotype/subtype.
In the present study, 134 consecutive patients who had previously been genotyped were retested using HCV sequence analysis to confirm a prior commercial test before beginning HCV treatment.
It was found that twenty-one (15.7%) HCV patients had been incorrectly genotyped. This error in genotype/subtype was estimated to reduce the treatment effectiveness by 15% to 40%.
There were 8 cases of genotype 1b that when retested were genotype 1a. This meant that the wrong treatment and/or treatment duration was given.
Lastly, there were 5 patients with HCV genotype 1 with an indeterminate subtype that could have, again, lead to the wrong treatment or treatment duration.
Four patients had mixed genotypes which is important to know because a pan-genotypic drug may be needed to treat those patients.
Editorial Comments
It is alarming that such a large number of incorrect genotypes/subtypes are being mis-classified by current assays. Can you imagine going through treatment multiple times and failing and finding out that the assay was wrong? You would think that for such an important diagnostic test the Food and Drug Administration (FDA) would require a higher rate of accuracy.
It's time to re-test people for genotype/subtype with the most sensitive test BEFORE therapy to make sure the correct medication is prescribed. The added cost of the assay is more than enough justification considering the cost of HCV medications and the welfare of a patient.
Source: ClinicoEconomics and Outcomes Research 2016:8 467-473.
Alan Franciscus is the executive director of the Hepatitis C Support Project and the editor-in-chief of the HCV Advocate website.