Sa1308 Hepatitis B (HBV) Viral Suppression Among Patients Treated With Entecavir and With Previous Treatment With Lamivudine or Other Antiviral Medications: Real-World Outcomes in a US Insured Population

Abstract

Background: Viral suppression associated with entecavir varies depending on patients' resistance to lamivudine (LAM; BMS, label). The literature suggests that in aggregate, among a patient population with a history of LAM treatment, the majority will not have developed LAM resistance, with resistance rates ranging from approximately 22% to 39% (MargeridonThermet, 2013; Cooley, 2003). The impact of prior LAM on viral suppression rates with entecavir in a real-world patient population is unclear. Objective: To estimate viral suppression among entecavir-treated HBV patients previously treated with LAM versus with other antiviral medications. Methods: This retrospective study included medical and pharmacy claims, enrollment data, and laboratory results (1995-2013) from 2 large national health plan databases. Subjects were commercial and Medicare Advantage enrollees who newly initiated entecavir treatment between March 2005 and August 2012 and were previously treated with LAM or other antiviral medications. Index date was the first entecavir prescription fill. Patient cohorts were based on previous treatment: LAM and other antiviral medication (OTH). Viral suppression was identified using all HBV DNA laboratory results between 30 to 365 days after initiating and prior to discontinuing entecavir. Secondary analyses described viral suppression based on results within 1 year of initiating entecavir but that may have occurred after discontinuing entecavir. Logistic regressionmodeled viral suppression adjusted for patient characteristics (including age, gender, comorbid illnesses, and patient demographic characteristics). Results: Of 284 qualifying study subjects, 29.2% were LAM and 70.8% were OTH. Cohorts had similar mean age (LAM 45.8 vs. OTH 46.9 years, P=0.47) and a similar proportion of female patients (LAM 27.7% vs. 30.9%, P=0.60). Patients in the LAM cohort had lower pre-index comorbidity compared with OTH (Charlson score 1.9 vs. 2.5, P<0.001). Rates of viral suppression during entecavir treatment were 66.3% (LAM) vs. 73.1% (OTH), P=0.245). After adjustment for patient characteristics, the odds of viral suppression for LAM were not statistically different compared with the OTH cohort (odds ratio: 0.67; 95% CI: 0.37, 1.20). Compared with patients enrolled in commercial health plans, patients enrolled in Medicare Advantage plans had lower odds of viral suppression (OR=0.17; 95% CI: 0.05, 0.57). Intent-to-treat analyses found that 65.6% (LAM) and 75.6% (OTH) experienced viral suppression any time during the 1-year follow-up period (P=0.062).Conclusions: For patients treated with entecavir, HBV viral suppression among patients previously treated with LAM was not substantially different from viral suppression among patients previously treated with other HBV antiviral medications. Table 1: HBV viral suppression while on entecavir treatment