Study population

This retrospective study included NA-naive patients with CHB who received TDF at least 12 months before switching and TAF at least 12 months after switching at a single medical center. All patients had positive hepatitis B surface antigen (HBsAg) for >6 months. Indications for TDF treatment comprised the following: (1) patients with positive HBeAg having ALT levels of ≥5 times the upper limit of normal (ULN); (2) positive HBeAg having HBV deoxyribonucleic acid (DNA) levels of >20,000 IU/ml and ALT levels of >2 times the ULN; (3) negative HBeAg having with HBV DNA levels of >2,000 IU/ml and ALT levels of >2 times the ULN for >3 months; (4) chronic hepatitis B (CHB) having liver decompensation; (5) cirrhosis and HBV DNA levels of >2,000 IU/ml; or (6) CHB receiving chemotherapy (prophylaxis of HBV reactivation). The reasons for switching to TAF were all related to the unavailability of TDF due to the hospital pharmacy policy in our hospital. We excluded patients who had received NA or an interrupted antiviral therapy for >2 weeks, had concomitant medications with other NAs, or were coinfected with hepatitis C virus (HCV) or HIV. The participants were enrolled between December 2011 and March 2021.