Materials and Methods
We performed a retrospective, longitudinal study in a cohort of 169 prospectively followed chronic HBV naïve HBeAg-positive and HBeAg-negative patients treated with ETV for at least 6 months since January 2005, in 8 centres in Argentina. Patients older than 18 years, HBV DNA positive, HBeAg positive or negative, and treatment naïve were included. We excluded patients treated in RCTs, with HIV and/or HCV coinfection, with solid organ transplantation, on haemodialysis or with other associated liver disease. Data were obtained from the medical records and anonymously entered in a database.
We report our virological and serological results with continued treatment up to 1 March 2013 or until stopping it according to international recommended stopping rules. We evaluated the effect of ETV 0.5 mg/day treatment on HBV DNA negativization, HBeAg negativization, anti-HBe seroconversion, HBsAg negativization, anti-HBs seroconversion and virological and serological relapse rates. We also evaluated the influence of baseline demographic characteristics, alanine aminotransferase (ALT) levels (mean and ≥5 times upper limit of normal-ULN), HBV DNA levels (mean and ≥7 log10 IU/mL), Metavir scores, presence of cirrhosis and ETV treatment duration on relapse rates. Treatment duration was defined according to the current stopping rule guidelines: discontinuation after 48 weeks of anti-HBe seroconversion in HBeAg-positive patients and indefinitely in HBeAg-negative patients, or after achieving HBsAg/anti-HBs seroconversion. The following parameters were recorded at baseline and every 24 weeks during treatment or after its discontinuation: liver function tests; complete blood counts; serum HBV DNA levels; and HBsAg, anti-HBs, HBeAg and anti-HBe status. Serological and virological tests were performed at any time, according to clinical criteria of the treating physician. The diagnosis of liver cirrhosis was based on liver biopsy, imaging studies or clinical and biochemical parameters.
Diagnosis of chronic hepatitis B was defined as a positive serum HBsAg and detectable HBV DNA for more than 6 months, independent of ALT levels and HBeAg status. Haematological and biochemical assays were performed using automatical techniques. Quantitative HBV DNA was determined by Cobas TaqMan HBV 'real-time PCR' test (Roche Molecular systems Inc., Branchburg, NJ, USA) with a limit of detection of 6 IU/mL (0.78 log). HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc were assessed by microparticle enzyme immunoassay assay (MEIA) (Abbott Diagnostics Division, Abbott Park, IL, USA). HBV genotypes were not evaluated. Virological relapse was defined as an increase in serum HBV DNA to >2000 IU/mL after discontinuation of treatment. Serological relapse was defined as reappearance in serum of HBeAg and/or HBsAg after discontinuation of treatment. In case of virological breakthrough, ETV resistance was evaluated by direct sequencing of the viral genome.
Treatment was indicated and monitored according to national and international guidelines. In some cases, doses might be different to those recommended, according to individual medical judgement. Management of adverse events (AEs), including dose modifications and/or treatment discontinuation, was decided by the treating physicians according to national and international guidelines and to their own clinical judgement. This study was conducted in accordance with the Declaration of Helsinki, Good Clinical Practice. The study was approved by the Ethics and Research Committee of the Centro de Educación Médica e Investigaciones Clínicas Norberto Quirno 'CEMIC'.
Microsoft Excel 2007® software (Microsoft, Seattle, WA, USA) was used for the database. STATA® statistical software was used for the analysis (version 11.0; Stata Corporation, College Station, TX, USA). The chi-square and Fisher's exact tests were employed to compare categorical variables, and continuous variables were compared using the t-test and the Mann–Whitney U-test. Cox proportional hazard model was used to explore base-line factors predicting a virological response. P value <0.05 was considered statistically significant.