Prevalence of pre-treatment hepatitis C virus NS5A resistance associated amino-acid substitutions in genotype 1A infected patients in Scotland.

BACKGROUND: Hepatitis C (HCV) NS5A resistance associated amino-acid substitutions (RAS) can exist at baseline in treatment naïve individuals and have been shown to be associated with lower rates of sustained virological response (SVR) for patients infected with HCV genotype 1A (G1A) following treatment with NS5A inhibitors. OBJECTIVES: The aim of this study was to measure the prevalence of baseline NS5A resistance in Scotland. STUDY DESIGN: The study population consisted of 531 treatment naïve, G1A infected patients. The patient samples were collected between March and September 2017. The NS5A region was amplified and sequenced. RESULTS: Baseline NS5A resistance in Scotland is high (16.8%) and is comparable to rates reported by a number of previously published studies. The high rate of baseline RAS, together with the high cost of direct-acting antivirals (DAAs), supports resistance testing to guide current patient treatment. However, given the rate at which new DAAs are currently being licensed with ever broader genotype efficacy and higher SVR rates, baseline resistance testing may not be required in the near future. CONCLUSIONS: Baseline NS5A inhibitor resistance is high. The results of the present study support performing resistance testing at baseline for current regimens.