September 6, 2012
Vincent Lo Re III et al. AIDS Behav 2012; epublished ahead of print. Read the abstract.
We know a lot about adherence to antiretroviral therapy. However, even though more of us are playing the hepatitis C virus (HCV)-treatment game, there is much less understood about how coinfected individuals take their HCV therapies. Treatment for HCV and HIV differ markedly from one another. HCV therapy involves injected medication, produces adverse effects in almost all, and although it is taken for a limited time and can be curative, it may be harder to adhere to than HIV medications.
A group from the University of Pennsylvania's Perelman School of Medicine assessed adherence to HCV therapy with pegylated interferon and ribavirin and its association with early and sustained virologic responses in 333 patients treated across the VA system. Adherence, as in the antiretroviral adherence study described above, was measured using pharmacy refill data and was assessed for those who remained on HCV therapy. The patients were almost all male, 44% were African American, 68% had undetectable HIV-RNA levels, 80% were HCV genotype 1 or 4, and 30% had a history of depression.
Of the 333 patients, all obtained prescription fills during the first 12-week adherence interval, 239 during the second interval, 150 during the third interval, and 106 during the fourth interval. Adherence to interferon was higher at all intervals than that to ribavirin. For both drugs, adherence tended to decline over time dropping from 100% during the first 12 weeks to 88% during weeks 37-48 for interferon and from 93% to 78% for ribavirin during the same time intervals. Methadone use was associated with poorer adherence while the use of growth factors was associated with higher levels of adherence.
A total of 72/267 (27%) patients with genotype 1 or 4 and 33/66 (50%) with genotype 2 or 3 achieved a sustained virologic response. Interestingly, for the genotype 1 and 4 patients, a sustained virologic response was more likely with higher adherence levels to interferon, and to a lesser extent ribavirin, during the first 36 weeks of therapy but not during weeks 37-48 (this held up even when looking at those without ribavirin dose reductions). These results are similar to adherence rates observed in HCV mono-infected patients, and the declines over time in the coinfected were actually lower than those seen in a study of mono-infected VA patients.
The study raises an alarm with the availability of newer HCV agents that, like ribavirin, are taken orally and dosed multiple times a day. Supporting adherence to these direct acting agents will need to be paramount if their benefits are to be maximized.
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