www.hivandhepatitis.com

Adherence to Interferon-Based Therapy for Hepatitis C Slips Over Time

Adherence to interferon-based therapy for hepatitis C virus (HCV) infection tends to decrease over time, and poorer adherence leads to lower likelihood of sustained virological response, researchers reported in the September 20, 2011, Annals of Internal Medicine.

Maintaining good adherence to hepatitis C treatment is important for achieving good response. Several studies have found that "80/80/80" adherence-- taking at least 80% of prescribed interferon dose and 80% of prescribed ribavirin dose for at least 80% of the standard course of therapy -- is associated with higher rates of sustained response (SVR). But factors predicting good adherence and changes over time are not fully understood.

Vincent Lo Re and colleagues from the University of Pennsylvania Perelman School of Medicine and Philadelphia Veterans Affairs Medical Center evaluated the relationship between adherence to hepatitis C therapy and early and sustained virological response, looking at changes in adherence over time and risk factors for non-adherence.

This retrospective cohort study analyzed data from the National Veterans Affairs Hepatitis C Clinical Case Registry. The analysis included 5706 hepatitis C patients with HCV genotypes 1, 2, 3, or 4, who had received at least 1 prescription for both pegylated interferon and ribavirin between 2003 and 2006.

Adherencewas calculated over 12-week intervals using pharmacy refill data. Endpoints included early virological response (EVR; HCV RNA decrease of at least 2 log at 12 weeks) and SVR (undetectable HCV RNA 24 weeks after the end of treatment).

Results

• The likelihood of early virological response increased with higher levels of adherence to ribavirin over the initial 12 weeks:

o      Patients with HCV genotype 1 or 4: 37% EVR with < 40% adherence vs 63% EVR with 91%-100% adherence;

o      Patients with HCV genotype 2 or 3: 67% vs 91% EVR, respectively.

• Among patients with HCV genotype 1 or 4, likelihood of sustained response increased with higher adherence to ribavirin over the second, third, and fourth 12-week intervals.
• Results were similar for adherence to pegylated interferon.
• Average interferon adherence decreased by 3.4% per 12-week interval.
• Average ribavirin adherence decreased by 6.6% per 12-week interval.
• Patients who received blood cell growth factors (erythropoietin for anemia or colony-stimulating factors for neutropenia) or thyroid medications during treatment had higher mean adherence.

Based on these findings, the study authors concluded, "Early and sustained virologic responses increased with higher levels of adherence to interferon and ribavirin therapy."

"Adherence to therapy with both antivirals decreased over time, but more so for ribavirin," they added.

"Our findings are particularly timely since many chronic hepatitis C patients are now being prescribed direct-acting antiviral drugs, which have a complex dosing regimen that may be even harder for patients to maintain than the 2-drug standard therapy," Lo Re said in a University of Pennsylvania press release. "These data show us that we need to develop and test interventions to help patients be more successful at taking their medicine and have the best chance at being cured."

"We know that a major barrier to adherence is side effects of these drugs. People don't feel good when they're on them," he continued. "If we can identify those problems and treat them when they occur, patients may be more motivated and feel well enough to continue with their prescribed regimen."

Investigator affiliations: University of Pennsylvania School of Medicine and Philadelphia Veterans Affairs Medical Center, Philadelphia, PA.

10/4/11

Reference

V Lo Re, V Teal, AR Localio, et al. Relationshipbetween adherence to hepatitis C virus therapy and virologic outcomes: a cohort study. Annals of Internal Medicine155(6):353-360 (abstract). September 20, 2011.

Other Source

University of Pennsylvania School of Medicine. Adherence to Hepatitis C Treatment Falters. Press release. September 29, 2011.