Achieving an undetectable hepatitis C virus (HCV) viral load by the fourth week of HCV treatment is highly predictive of treatment effectiveness in people also with HIV, according to study results published in the January 2 issue of AIDS. These new findings suggest that people infected with both viruses can use a simple lab test to determine whether or not to continue potentially toxic therapy with a reasonable chance of long-term success.

In the PRESCO study, conducted by Luz Martin-Carbonero, MD, of the Hospital King Carlos III in Madrid and her colleagues, 389 HIV/HCV-positive patients received pegylated interferon plus 1,000 to 1,200 mg ribavirin. People with the easier-to-treat HCV types 2 or 3 were treated for six or 12 months; patients with harder-to-treat HCV types 1 or 4 were maintained on therapy for 12 or 18 months.

The researchers evaluated rates of sustained virologic responses (SVR)—i.e., the number of people who maintained undetectable HCV viral loads six months after completing treatment.

According to Martin-Carbonero’s team’s report, approximately 50 percent of people with HCV type 1, 100 percent of people with HCV type 2, 72 percent of people with HCV type 3, and 33 percent of people with HCV type 4 had an SVR. The researchers also noted that if patients’ HCV viral loads were undetectable after four weeks of being on treatment, their chances of a sustained virologic response were excellent.

This is critical information for people infected with both HCV and HIV. While prior research established that week-4 treatment responses are predictive of SVRs in people infected with HCV, the PRESCO data are among the first to confirm this in HCV/HIV-coinfected patients.