Adherence to Hepatitis C Virus Therapy and Early Virologic Outcomes

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http://www.journals.uchicago.edu/doi/abs/10.1086/595685

Clinical Infectious Diseases 2009;48:186–193

DOI: 10.1086/595685

MAJOR ARTICLE

Adherence to Hepatitis C Virus Therapy and Early Virologic Outcomes

Lo Re III,1,2,3,4

Valerianna K. Amorosa,1,4

A. Localio,2,3

Rose O'Flynn,4

Teal,2

Zachariah Dorey-Stein,1

Jay R. Kostman,1 and

Gross,1,2,3,4

1Division of Infectious Diseases, Department of Medicine, 2Department of

Biostatistics and Epidemiology and Center for Clinical Epidemiology and

Biostatistics, and 3Center for Education and Research on Therapeutics,

University of Pennsylvania School of Medicine and 4Philadelphia Veterans Affairs

Medical Center, Philadelphia, Pennsylvania

Background. Suboptimal drug exposure attributable to physician-directed dosage

reductions of pegylated interferon and/or ribavirin are associated with

decreased sustained virologic response rates. However, data are limited with

regard to suboptimal drug exposure that is attributable to missed doses by

patients with chronic hepatitis C virus (HCV) infection. We examined the

relationship between adherence to pegylated interferon and ribavirin therapy,

measured by pharmacy refill, and HCV suppression during the initial 12 weeks of

therapy.

Methods. We conducted a cohort study involving 188 patients with chronic HCV

infection who were treated with pegylated interferon plus ribavirin. Adherence

was calculated using pharmacy refill data and could exceed 100%. The primary

outcome was decrease in HCV load at 12 weeks; early virologic response was a

secondary outcome. Mixed-effects regression models estimated the association

between adherence and HCV suppression during the initial 12 weeks. Subanalyses

were performed among patients who received optimal weight-based dosages.

Results. The mean decrease in HCV load at 12 weeks was 0.66 log IU/mL greater

for patients with 85% adherence than for those with