Clinical Efficacy and Safety of Long-Term Treatment of Tenofovir Alafenamide vs Tenofovir Disoproxil Fumarate for Chronic Hepatitis B in Vietnam

INTRODUCTION: Hepatitis B virus (HBV) infection is a contagious condition posing a major public health risk in various nations, including Vietnam. In 2019, the Ministry of Health introduced tenofovir alafenamide (TAF) to treat patients with chronic HBV infection and reduce the long-term toxicity of tenofovir disoproxil fumarate (TDF). This study aimed to assess the effectiveness and safety of these 2 medications in individuals with hepatitis B e antigen (HBeAg)-positive chronic HBV. METHODS: This retrospective cohort study included data collected from the medical records of patients with chronic HBV who visited the Liver Clinic at University Medical Center Ho Chi Minh City between 2018 and 2020. RESULTS: After 2 years of treatment, the proportion of HBeAg loss in the TAF group was twice that of the TDF group (22.4% vs 11.2%), indicating a statistically significant difference in the probability of HBeAg loss (adjusted hazard ratio = 2.22; 95% confidence interval [CI] 1.43-3.42; P < 0.01). In addition, there was a statistically significant difference in the rate and ability of antiviral response between patients treated with TAF and TDF (65% vs 54.5%, respectively; adjusted hazard ratio = 1.34; 95% CI 1.08-1.69; P < 0.01). A total of 93.9% of patients achieved the goal of restoring alanine aminotransferase to normal, a higher percentage compared with the 81.2% in the TDF group, and the likelihood of achieving normal alanine aminotransferase levels with TAF was greater compared with those on TDF (adjusted hazard ratio = 1.67; 95% CI 1.38-2.01; P < 0.01). Moreover, there was a statistically significant difference in the variation in renal function between the TAF and TDF groups. Serum creatinine levels in the TAF group increased less than those in the TDF group by 0.03 mg/dL every 6 months (95% CI -0.04 to -0.01, P < 0.01), and the estimated glomerular filtration rate in the TAF group was higher than that in the TDF group every 6 months by 2.78 mL/min/1.73 m2 (95% CI 0.98-4.57, P < 0.01). However, there was no statistically significant difference in the likelihood of HBeAg seroconversion between patients with chronic hepatitis B treated with TAF or TDF (adjusted hazard ratio = 1.79; 95% CI 0.91-3.53; P = 0.09), nor in the risk of adverse events between the 2 groups (adjusted odds ratio = 1.34; 95% CI 0.88-2.05; P = 0.17). In addition, although the HBsAg concentration in the TAF group was lower than in the TDF group by an average of 0.05 log10 IU/mL every 6 months (95% CI -0.15 to 0.05), this difference also did not reach statistical significance (P = 0.35). DISCUSSION: TAF has been demonstrated to achieve some therapeutic efficacy goals and reduce nephrotoxicity better than TDF. However, no differences were found in seroconversion or adverse events between the patient groups.