Is there a difference between preoperative and postoperative delirium in elderly hip fracture patients?: A retrospective case control study

Delirium is associated with greater morbidity, higher mortality, and longer periods of hospital day after hip fracture. There are number of studies on postoperative delirium after a hip fracture. However, few studies have made a distinction between preoperative and postoperative delirium. The purpose of this study is to compare risk factors and clinical outcome between preoperative and postoperative delirium in elderly patients with a hip fracture surgery. A total of 382 consecutive patients aged > 65 years who underwent operation for hip fracture were enrolled. Among them, the patients diagnosed with delirium were divided into 2 groups (a preoperative delirium group and a postoperative delirium group) according to the onset time of delirium. To evaluate risk factors for preoperative and postoperative delirium, we analyzed demographic data, preoperative laboratory data, and perioperative data. To compare clinical outcomes between preoperative and postoperative delirium, we analyzed postoperative complications, KOVAL score, regression, readmission, and 2-year survival rate. Delirium was diagnosed in 150 (39.3%) patients during hospitalization. Preoperative and postoperative delirium occurred in 67 (44.6%) and 83 (55.4%) patients, respectively. Independent risk factors of preoperative delirium included age (odds ratio: 1.47, 95% confidential interval [CI]: 1.13-2.23, P = .004), stroke (odds ratio [OR]: 2.70, 95% CI: 1.11-6.01, P = .015), American Society of Anesthesiologist (OR: 1.68, 95% CI: 1.137-2.24, P = .033), and time from admission to operation (OR: 1.08, 95% CI: 1.01-1.16, P = .031). There was no significant difference in preoperative KOVAL score between the 2 groups. However, postoperative KOVAL score (5.1 ± 2.0 vs 4.4 ± 2.1, P = .027) and regression rate (68.7% vs 44.6%, P = .029) were significantly higher in the preoperative delirium group than in the postoperative delirium group. Moreover, the 2-year survival rate was significantly lower in the preoperative delirium group than in the postoperative delirium group (62.7% vs 78.3%, P = .046). Characteristics, risk factors, and prognosis are different for patients with preoperative delirium and postoperative delirium. Preoperative delirium patients showed different risk factors with poorer prognosis and higher mortality. Therefore, hip fracture patients with risk factors for preoperative delirium should be monitored more carefully due to their greater risk of mortality.