BACKGROUND & AIMS: Long-term treatment with nucleos(t)ide analogues (NUCs) is associated with increasing rates of antiviral drug resistance. Medication adherence is important in preventing drug resistance. This study aimed to determine, first, the persistence rates and the adherence rates to NUCs in patients with chronic hepatitis B (CHB), and second, the factors associated with adherence.
METHODS: Pharmacy claims of three cohorts of patients with CHB who were receiving lamivudine, adefovir, or entecavir in January 2007, January 2008, and January 2009, and data of patients receiving tenofovir in January 2009, were analyzed. Persistence was defined as continuing acquisition of pharmacy claims during a 12-month period and adherence as the percent of days in which patients had medication during the period in which the medication was prescribed.
RESULTS: A total of 11,100 patients were included, 4.7% were patients newly started on a NUC and 95.3% were existing patients already on a NUC at the start of each year. The mean � SD persistence rate was 81 � 3.8%, and was higher among existing patients than among new patients, 81.4% vs. 73.4% (p < 0.001). The mean � SD adherence rate was 87.8 � 19.1% and was higher among existing patients than among new patients, 88% vs. 84.6% (p = 0.001). Multivariate analysis showed that new patients (OR = 0.68, 95% CI 0.53-0.86), those receiving lamivudine (OR = 0.66, 95% CI 0.58-0.76), and young adult patients (OR=0.82, 95% CI 0.74-0.91) were less likely to have adherence rate > 90%.
CONCLUSIONS: Persistence and adherence to NUCs were high among CHB patients. Counseling of young and/or new patients on medication adherence may decrease the rate of antiviral drug resistance.