Increased spine bone density in patients with chronic hepatitis B switched to tenofovir alafenamide: A prospective, multinational study

Background: Data on patients switched to tenofovir alafenamide (TAF) from nucleos(t)ide analogues (NUCs) other than tenofovir disoproxil fumarate are limited.Aims: To assess the treatment and renal/bone safety outcomes following the switch to TAF.Methods: We prospectively enrolled adult patients with chronic hepatitis B (CHB) who switched from any NUC to TAF at 14 centres in Japan, Korea, Taiwan and the U.S. Study outcomes were viral suppression (VR; HBV DNA < 20 IU/mL), biochemical response (BR; alanine aminotransferase normalisation), and changes in estimated glomerular filtration rate (eGFR) and T-scores (L-spine) by bone absorptiometry by 24 months after switch to TAF.Results: We enrolled 270 eligible patients. Mean age was 58.1; 58.2% were male; 12.2% had cirrhosis and 73.3% previously received entecavir monotherapy. VR rate increased significantly from 95.2% to 98.8% by 24 months after the switch to TAF (p = 0.014). Between the switch and 24 months later, the mean spine T-score improved significantly from -1.43 +/- 1.36 to -1.17 +/- 1.38 (p < 0.0001), while there was no significant change in mean eGFR (88.4 +/- 16.9-89.5 +/- 16.3 mL/min/1.73 m(2), p = 0.13). On multivariable analysis adjusted for age, sex, baseline spine T-score and prior TDF or adefovir dipivoxil use, male sex was significantly associated with lower risk of worsening spine T-score (odds ratio: 0.29, p = 0.020), while age was significantly associated with a higher risk of worsening chronic kidney disease stage (OR: 1.07, p = 0.019).Conclusions: At 24 months after the switch to TAF, VR rates and spine bone density improved significantly while renal function remained stable.