We reclassified bleeding events in the selected studies according to our defined criteria to allow pooling of findings across studies based on standardized definitions of bleeding outcomes. This was necessary because no accepted standardized definition of bleeding for patients undergoing surgical procedures exists.15 We defined thromboembolic events as stroke, transient ischemic attack, systemic embolism, thrombosis of a mechanical heart valve, thrombosis of the cardiac chamber, deep-vein thrombosis or pulmonary embolism. We defined all-cause mortality as death from any cause. We resolved disagreements about data extraction by consensus and discussion with a fourth reviewer (JD).