Effect on the adherence to concomitant medications after initiation of treatment with direct-acting antiviral agents against hepatitis C virus.

INTRODUCTION: Many patients with hepatitis C virus (HCV) have associated comorbidities that require complex treatments. We sought to determine the impact of treatment with direct-acting antiviral agents (DAAs) for HCV on adherence to prescribed concomitant medications for associated comorbidities and to identify predictors of non-adherence to comedications. PATIENTS AND METHODS: HCV-infected patients treated with DAAs in a Spanish hospital between January 2015 and December 2016 and followed-up by the pharmacy unit were included in the study. Adherence to concomitant comedication prescribed before and during HCV therapy with DAAs was compared to adherence during the same number of weeks before DAA initiation. Demographic, clinical and pharmacotherapy variables were analyzed to determine factors associated with non-adherence. A multivariate regression model was created for prediction of non-adherence to concomitant medication. RESULTS: Data from 214 patients using prescribed concomitant therapies were analyzed. Significant reduction on adherence to comedications was observed after initiation of DAA treatment compared with a similar period before therapy initiation (29.9% vs. 36.9%, p=0.032). The univariate analysis showed that polypharmacy and presence of vascular disease were associated negatively with adherence to concomitant medications (87.8%, p=0.006 and 84.7%, p<0.001, respectively). Multivariate analysis indicated that HIV/HBV coinfection was associated with adherence (OR 0.19; 95% CI 0.09-0.39), while polypharmacy was a predictor for non-adherence (OR 4.54; 95% CI 1.48-13.92). DISCUSSION: Adherence to concomitant medications decreases in HCV-infected patients when DAA therapy is initiated. Polypharmacy is a predictor for non-adherence, while HIV/HBV coinfection reduce non-adherence rates. Polymedicated patients on DAAs might benefit from close follow-up and educational programmes to improve their adherence.