Background: Limited data exist regarding tenofovir disoproxil fumarate (TDF) safety and effectiveness in chronic hepatitis B virus–infected (CHB) patients with renal impairment (RI). Aims: To compare real-world data on renal safety and effectiveness of TDF vs entecavir (ETV) in CHB patients with moderate-to-severe RI. Methods: Retrospective, non-interventional, cohort study analysing medical records for TDF/ETV-treated CHB patients (54 European centres). Included patients experienced moderate-to-severe RI (creatinine clearance 20-60 mL/min [Cockcroft-Gault]) either before TDF/ETV initiation (‘before’ subgroup [baseline = treatment initiation]) or after TDF/ETV initiation (‘after’ subgroup [baseline = first RI occurr...