Comparing drug interaction frequencies of various hepatitis C treatment regimens among monoinfected patients.

ABSTRACT

INTRODUCTION AND OBJECTIVES: Four regimens are recommended for treating hepatitis C (HCV) genotype 1 infection. Study aims were to (1) compare frequencies of contraindicated drug interactions (XDDIs) when each HCV regimen is added to medication profiles of HCV-monoinfected patients, (2) quantify the proportion of patients with XDDIs to all four regimens and (3) determine covariates independently associated with having a XDDI to all four regimens. MATERIALS AND METHODS: A cross-sectional study was performed within Upstate New York Veterans Healthcare Administration. INCLUSION CRITERIA (1) age ≥18 years, (2) HCV monoinfection and (3) available medication list. Data extracted were demographics, comorbidities, and medication list. Primary outcome was XDDIs involving patient's home medications and each HCV regimen. University of Liverpool drug interaction website was used to define XDDIs. Two-way comparisons of regimens were performed using McNemar's test where p<0.0083 was considered statistically significant. Multivariate regression analyses were performed to determine predictors. RESULTS: Of the 4047 subjects, mean±standard deviation age was 59.8±7.6. Median (interquartile range) number of medications used was 7 [4-11]. Frequencies of XDDIs after the addition of each regimen ranged from 2.8% to 17.8% and were mostly statistically different from one another. There were 95 (2.3%) patients with XDDIs to all four regimens. Predictors of having XDDIs to all four regimens were ≥6 medications and HCV infection ≥10 years. CONCLUSION: The frequencies of XDDIs varied between HCV regimens. Number of medications and duration of HCV infection were predictors of having XDDIs to all four regimens.