Factors associated with TDF-to-TAF switching in chronic hepatitis B: A nationwide cohort study in South Korea

Chronic hepatitis B, a primary cause of liver disease and cancer, requires long-term antiviral therapy. Tenofovir alafenamide (TAF), a novel targeted prodrug of tenofovir disoproxil fumarate (TDF), has reduced renal and bone toxicities while delivering comparable antiviral efficacy at a lower dose. This study aimed to identify factors associated with TAF switching within one year of its introduction in patients receiving TDF.

This retrospective cohort study included adult patients (≥18 years) with chronic hepatitis B who were receiving TDF on the day TAF became reimbursable in Korea, November 1, 2017. Antiviral prescriptions were tracked for one year to identify patients who switched to TAF. Switching rates were calculated as events per 100 person-months. Factors associated with TAF switching were evaluated using Cox proportional hazards models.

Among 95,819 patients receiving TDF on the index date, 1.4 % switched to TAF within one year. Switching was more likely in males, older adults, and those with hypertension, renal disease, or bone disease. Use of angiotensin-converting enzyme inhibitors (ACEis)/angiotensin II receptor blockers (ARBs) was associated with an increased likelihood of switching, whereas nonsteroidal anti-inflammatory drug use and the presence of hepatocellular carcinoma were associated with lower odds. Patients treated in Seoul and at tertiary hospitals had higher switching rates than those in other regions or healthcare settings.

In this nationwide cohort study, the TAF switching rate among patients receiving TDF was 1.4 % within one year of TAF's reimbursement approval in South Korea. Switching was significantly associated with renal disease, bone disease, age ≥60 years, hypertension, and ACEi/ARB use. Although the higher switching rate in patients with renal or bone disease aligns with reimbursement criteria, other at-risk groups not currently covered may benefit from earlier access.