Incidence, clinical impact and risk of bleeding during oral anticoagulation therapy

Table 1 Different definitions of major bleeding in various studies

Ref.	Clinical setting	Definition
Landefeld et al[53]	Various	Fatal, life-threatening, potentially life-threatening, causing severe blood loss, leading to surgical treatment or moderate acute/subacute blood loss not explained by surgery/trauma
Palareti et al[32]	Various	Fatal intracranial (documented by imaging); ocular (with blindness); articular; retroperitoneal; requiring surgery/angiographic intervention; associated to Hb decrease ≥ 2 g/dL or need for ≥ 2 blood units transfusion
Beyth et al[54]	Various	Overt bleeding leading to ≥ 2 blood units loss in ≤ 7 d, or life-threatening
Gage et al[55]	AF	ICD-9CM codes for bleed in any location
Shireman et al[56]	AF	Hospitalization for “major acute bleeding” (including gastrointestinal or intracranial hemorrhage)

AF: Atrial fibrillation; Hb: Hemoglobin.