Background: Five regimens are recommended for patients with hepatitis C (HCV) genotype 1 infection. Drug interactions may occur when new medications are added. Study objectives were to 1) compare excess frequencies of contraindicated drug interactions (XDDIs) when each HCV regimen is added to medication profiles of HCV-monoinfected patients and 2) determine covariates independently associated with having an XDDI to all 5 regimens.
Methods: A cross-sectional study was performed within Upstate New York Veterans Healthcare Administration. Inclusion criteria were: 1) age≥18 years, 2) HCV monoinfection & 3) available medication list. Data extracted were: demographics, comorbidities, and medication list. Primary outcome was XDDIs involving patient's home medication list and addition of each HCV regimen. Lexi-Interact drug interaction software was used to define XDDIs. Only X-rated interactions were considered clinically significant. Two-way comparisons of regimens were performed using McNemars test. Multivariate regression analyses were performed to determine predictors. Given large sample size, p<0.01 was considered statistically significant.
Results: Of the 4,255 subjects, mean ± standard deviation (SD) age and number of comorbidities were 59.0±7.6 and 7.9±3.7, respectively. Median (interquartile range) medication use was 7 (4-11). Prior to the addition of HCV therapy, the baseline XDDI prevalence was 16.7%. The excess frequencies of XDDIs after the addition of each regimen are in Figure 1. Frequencies of XDDIs for each regimen statistically differed from one another. Predictors of having XDDIs to all 5 regimens were number of medications (prevalence ratio, PR: 1.05; 95% confidence interval, CI: 1.011.09; p=0.007) and presence of epilepsy/seizure disorder (PR: 34.0, 95% CI: 21.454.1, p< 0.001).
Conclusion: Frequencies of XDDIs varied between HCV regimens. Number of medications and epilepsy/seizure disorder were predictors of having XDDIs to all 5 regimens.
R. Amin, None
K. R. Delehanty, None
J. Yager, None
N. Patel, Gilead: Grant Investigator , Grant recipient
Merck: Grant Investigator , Grant recipient