A group of American researchers investigated the response to initial therapy with interferon (IFN) plus ribavin in patients with chronic hepatitis C.
They examined whether they could predict the response by measuring serum HCV RNA levels during the therapy.
A total of 912 treatment-naïve patients were enrolled in the study.
| Detectable HCV RNA at 24 weeks correctly identified 99% of nonresponders.
| Journal of Viral Hepatitis |
Each was randomized to receive IFN-alpha-2b, 3 million units three times weekly, for 24 or 48 weeks, with either ribavirin or placebo. They were then followed for 24 weeks.
Serum HCV RNA was measured at weeks 4 and 12 in patients treated for 24 weeks. For those treated for 48 weeks, it was measured at 4, 12, and 24 weeks. HCV RNA was also measured at week 24 post-therapy in all patients.
Sustained response was defined as loss of serum HCV RNA at 24 weeks follow-up. Other patients were considered virologic nonresponders.
For patients receiving 48 weeks of combination therapy, detectable serum HCV RNA at week 24 predicted nonresponse (positive predictive value) in 99% of patients. This was compared to 89% at week 12.
In patients treated for 24 weeks, testing at week 12 was more predictive of nonresponse than testing at week 4 in the combination-therapy group. This was not true in the monotherapy group.
John G. McHutchison, Medical Director of the Liver Transplantation Unit, Scripps Clinic and Research Foundation, La Jolla, California, concluded on behalf of his colleagues, "For combination therapy, testing for serum HCV RNA as a predictor of nonresponse is most accurate at week 24 of therapy. A positive test correctly identified 99% of nonresponders."