Effectiveness and Safety of Apixaban in Japanese Elderly Atrial Fibrillation Patients With Extremely Low Body Weight

Purpose Although direct oral anticoagulants are effective and safe in preventing stroke in atrial fibrillation (AF) patients with low body weight, data remain limited in AF patients with extremely low body weight (< 50 kg). We aimed to investigate the effectiveness and safety of apixaban in this category of patients. Methods The J-ELD AF Registry is a large-scale, multicenter prospective observational study of Japanese non-valvular AF patients aged ≥ 75 years taking on-label doses of apixaban. The entire cohort (3,025 patients from 110 institutions) was divided into three body weight subgroups: >60 kg (n = 1,019, 33.7 %), 50–60 kg (n = 1,126, 37.2 %), and < 50 kg (n = 880, 29.1%). Results The event incidence rates (/100 person-years) were 1.69, 1.82 and 1.23 for stroke or systemic embolism (P = 0.60); 1.37, 1.73 and 2.73 for bleeding requiring hospitalization (P = 0.154); 2.02, 2.67 and 4.92 for total death (P = 0.003); and 0.73, 0.95 and 1.23 for cardiovascular death (P = 0.57), respectively. After adjusting for confounders by Cox regression analysis, body weight < 50 kg was an independent risk for total death but not for stroke or systemic embolism, bleeding requiring hospitalization or cardiovascular death. Conclusions The incidence of events in each body weight group was comparable for stroke or systemic embolism, bleeding requiring hospitalization, and cardiovascular death, and significantly higher for total death in the body weight < 50 kg group in Japanese non-valvular AF patients aged ≥ 75 years taking on-label doses of apixaban.