Rapid viral response and treatment outcome in genotype 2 and 3 chronic hepatitis C: comparison between two HCV RNA quantitation methods

Fifty consecutive patients with genotype 2 or 3 chronic hepatitis C were treated with peg-IFN alfa-2a 135 microg weekly and ribavirin (11 mg/kg body weight) daily during 24 weeks. Rapid viral response treatment week 4, end-of-treatment response, and sustained viral response were analyzed by two different HCV RNA quantitation methods, the Cobas Amplicor Monitor test and the TaqMan test with a sensitivity of 600 and 15 IU/ml, respectively. The TaqMan test differentiated patients with rapid viral response finally achieving sustained viral response better. Hence, patients with and without rapid viral response as tested by the TaqMan test finally achieved sustained viral response in 97% (32/33) versus in 75% (12/16), P < 0.017. The corresponding figures for the Cobas Amplicor test was 91% (41/45) versus (80%) 4/5 a non-significant difference. In conclusion, the more sensitive TaqMan test yielded a lower number of patients with rapid viral response than the less sensitive Amplicor Monitor test, but predicted sustained viral response in a higher percentage of patients with rapid viral response than the Amplicor Monitor test. A rapid viral response meaning HCV RNA levels <15 IU/ml predicted a sustained viral response in 97% of patients with genotype 2 or 3.