Anticoagulant activity of apixaban can be estimated by multiple regression analysis

Background Information on apixaban anticoagulant activity is required to prevent major bleeding or thrombosis during its use. Methods We enrolled 194 patients with nonvalvular atrial fibrillation (NVAF) in whom warfarin was replaced with apixaban: 105 (54.1%) received the standard dose of apixaban (5 mg twice daily [BID]; 5 mg group) and 89 (45.9%) received a reduced dose (2.5 mg BID; 2.5 mg group). Multiple regression analysis was performed to predict the prothrombin time of apixaban (PTa) based on factors including age, body weight (BW), serum creatinine, and CHA2DS2‐VASc score. Results PTa and PT of warfarin (PTw) were significantly correlated in both groups (correlation coefficient R = 0.239 [P = .014] in the 5 mg group; R = 0.248 [P = .019] in the 2.5 mg group). PTa in the 5 mg group was predicted as follows: 16.952‐0.036 × BW +0.299 × CHA2DS2‐VASc score (P