The effect of melatonin on prevention of postoperative delirium after lower limb fracture surgery in elderly patients: a randomized double blind clinical trial

Background: Postoperative delirium is a common complication with a high morbidity rate. This study was designed to consider the effectiveness of melatonin in prevention and treatment of postoperative delirium. Methods: Seventy-two patients aged >60 years old with Abbreviated Mental Test (AMT) >8 scheduled for orthopedic surgery under spinal anesthesia, were randomly distributed equally to melatonin or placebo groups. In the melatonin group, the patients were given 5 mg melatonin capsules orally the night before surgery, the night of the operation, and two nights after the surgical operation at 9 pm. Likewise, in the placebo group, the patients received placebo in the same times. For diagnosis of postoperative delirium, the AMT test was used before the operation and three days after that. The Generalized estimating equations model (GEE) with logit link to Multivariate analysis was used in the study and P