Prevention of Postoperative Delirium With Donepezil

Patients undergoing hip or knee joint replacement at the age of 70 years or above who are cognitively unimpaired will receive donepezil or matching placebo before (over 5-7 days), during and after (over 7 days) surgery. The incidence of delirium will be monitored at 3 days, 7 days, and 49 days following surgery. We hypothesize that the incidence of delirium can be lowered from 20 per cent to 10 per cent by the intervention.