Definitions:
Therapeutic anticoagulation was defined as low molecular weight heparin (LMWH) dosed as 1 mg/kg subcutaneously (SQ) every 12 hours to attain anti-FXa levels between 0.5 to 1, or unfractionated heparin (UFH) administered intravenously to attain anti-FXa levels of 0.3 to 0.7 and/or PTT of 70 to 110 seconds. Prophylactic anticoagulation was defined as LMWH 0.5 mg/kg SQ every 12 hours to attain anti-FXa level between 0.2 to 0.4 or adult dose of 40 mg SQ daily.
Bleeding was defined per International Society on Thrombosis and Hemostasis (ISTH) guidelines. Non major or minor bleeding was defined as overt bleeding requiring blood product transfusion (not directly attributable to the patient’s underlying condition), bleeding requiring medical or surgical intervention to restore hemostasis other than in the operating room, other bleeding for which medical attention has been sought and/or any overt macroscopic evidence of bleeding not fulfilling above criteria for major bleeding7. Major bleeding defined as fatal bleeding, symptomatic bleeding in a critical area or organ (like intracranial, intraocular, pericardial), and/or bleeding causing a fall in hemoglobin by 2 g/dL or more requiring transfusion of 2 or more units of while blood or red blood cells8.