Source Immunisation, Hepatitis and Blood Safety Department, Health Protection Services Colindale, Health Protection Agency, London, UK.

SUMMARY In a cohort of 272 treatment-naive individuals with chronic hepatitis C infection acquired on a known date who were enrolled in the UK HCV National Register, a progressive improvement in response to treatment was found with the evolution of antiviral therapies from 20% (25/122) for interferon monotherapy to 63% (55/88) for pegylated interferon+ribavirin therapy. Multivariable analysis results showed increasing age to be associated with poorer response to therapy [odds ratio (OR) 0•84, 95% confidence interval (CI) 0•72-0•99, P=0•03] whereas time since infection was not associated with response (OR 0•93, 95% CI 0•44-1•98, P=0•85). Other factors significantly associated with a positive response were non-type 1 genotype (P<0•0001) and combination therapies (P<0•0001). During the first two decades of chronic HCV infection, treatment at a younger age was found to be more influential in achieving a sustained viral response than treating earlier in the course of infection.