To the Editor.
—We have read with interest the article by Marcantonio et al.1 It was surprising not to see any contribution by anesthesiologists to the protocol, as the anesthetic and postoperative pain regimens should significantly affect the incidence of delirium.Although this study attempted to find a preoperative predictive scale, failure to control for the anesthetic technique and intraoperative events admits a bias that might affect, if not negate, the results. Different anesthesiologists may administer drugs that produce frank delirium under some circumstances. Drugs such as droperidol or benzodiazepines, especially in the elderly, can cause confusion. Whether or not a regional anesthetic with or without sedation was administered would also be important. For example, it has been demonstrated that the incidence of thromboembolic events (including stroke) decreases with epidural anesthesia for vascular surgery.2These data should have been collected, and possibly controlled for, in this prospective study.
O'Hara DA, Kushins LG. Preoperative Prediction of Postoperative Delirium. JAMA. 1994;271(20):1573. doi:10.1001/jama.1994.03510440033016