Prevalence of resistance associated substitutions and efficacy of baseline resistance-guided chronic hepatitis C treatment in Spain from the GEHEP-004 cohort.

Treatment guidelines differ in their recommendation to determine baseline resistance associated substitutions (RAS) before starting a first-line treatment with direct-acting antivirals (DAAs). Here we analyze the efficacy of DAA treatment with baseline RAS information. We conducted a prospective study involving 23 centers collaborating in the GEHEP-004 DAA resistance cohort. Baseline NS5A and NS3 RASs were studied by Sanger sequencing. After issuing a comprehensive resistance report, the treating physician decided the therapy, duration and ribavirin use. Sustained virological response (SVR12) data are available in 275 patients. Baseline NS5A RAS prevalence was between 4.3% and 26.8% according to genotype, and NS3 RASs prevalence (GT1a) was 6.3%. Overall, SVR12 was 97.8%. Amongst HCV-GT1a patients, 75.0% had >800,000 IU/ml and most of those that started grazoprevir/elbasvir were treated for 12 weeks. In genotype 3, NS5A Y93H was detected in 9 patients. 42.8% of the HCV-GT3 patients that started sofosbuvir/velpatasvir included ribavirin, although only 14.7% carried Y93H. The efficacy of baseline resistance-guided treatment in our cohort has been high across the most prevalent HCV genotypes in Spain. The duration of the grazoprevir/elbasvir treatment adhered mostly to AASLD/IDSA recommendations. In cirrhotic patients infected with GT-3 there has been a high use of ribavirin.