Background. Delirium is a common and serious syndrome in elderly patients. The hypoactive type of delirium is known to have different characteristics, but further studies are needed to define the specificities of these characteristics. Our study aims at finding specific risk factors, especially estimated blood loss during operations of hyper- and hypoactive delirium in orthopedic elderly patients.Methods. One hundred and seventy-five elderly patients were evaluated using the Confusion Assessment Method (CAM) and the4thedition text revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). Trained psychiatrists interviewed the subjects directly at pre- and postoperative time points. We reviewed medical records after the patients were discharged.Results. Thirty-nine patients (22.3%) were diagnosed with multiple types of delirium, which included 17 hyperactive types (65.9%), 13 hypoactive types (33.3%), and 9 mixed types (23.1%). Although the mean estimated blood loss in patients with either hyper- or hypoactive symptoms was larger than in patients lacking these symptoms, the odds ratio was only significant in patients with hyperactive symptoms. In addition, age, preoperative daily function, and preoperative hyponatremia were found to be risk factors for hyperactive but not hypoactive symptoms.Conclusion. Patients with hypoactive symptoms had different risk factors than patients with hyperactive symptoms of delirium. The estimated blood loss, well-known risk factors for delirium, might be risk factors for only hyperactive delirium. The acute precipitating factors seemed to show stronger correlation with the hyperactive type of delirium than with the hypoactive type.

Cheolmin Shin, Sang Won Jeon, Seung-Hoon Lee, Chi-Un Pae, Narei Hong, Hyun Kook Lim, Ashwin A. Patkar, Prakash S. Masand, Hyonggin An, Changsu Han. Clin Psychopharmacol Neurosci 2023;21:135-46. https://doi.org/10.9758/cpn.2023.21.1.135

Kim J, et al. J Korean Med Sci. 2015 Nov;30(11):1667-1674. https://doi.org/10.3346/jkms.2015.30.11.1667