Anticholinergic burden of long-term medication is an independent risk factor for the development of postoperative delirium: A clinical trial.

•10.1% of the elderly cancer patients developed postoperative delirium.•More than 25% of the surgical elderly cancer patients had polypharmacy.•16.1% of the patients had long-term medication with anticholinergic side-effects.•Anticholinergic drug load was associated with postoperative delirium.•Age, ASA state, and stay on ICU were also associated with postoperative delirium.