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

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Summary 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 m2, 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.