Patients were assigned to take aspirin ( 200 mg ) or placebo 2 to 4 hours before surgery and then aspirin ( 100 mg ) or placebo daily up to 30 days after surgery , and were assigned to take oral clonidine ( 0.2 mg ) or placebo 2 to 4 hours before surgery , and then a transdermal clonidine patch ( which provided clonidine at 0.2 mg/d ) or placebo patch that remained until 72 hours after surgery .