Predictive nomogram for postoperative delirium in elderly patients with a hip fracture

To evaluate the risk factors for the development of postoperative delirium and design a predictive nomogram for the prevention of delirium in elderly patients with a hip fracture, we retrospectively studied 825 patients who sustained a femoral neck fracture from January 2005 to December 2015. Independent risk factors for developing delirium within 6 months of surgery were identified using multivariable logistic regression analyses. A predictive nomogram model was built based on the results, and the discrimination and calibration were determined by C-index and calibration plot. Of the 825 patients who met inclusion criteria, 118 (14.3%) developed postoperative delirium. According to the results, preoperative cognitive impairment (OR, 4.132, 95% CI, 1.831 to 9.324, P＜0.001), multiple medical comorbidities (OR, 1.452, 95% CI, 0.958-2.202, P = 0.079), ASA classification (OR, 1.655, 95% CI, 1.073-2.553, P = 0.023), transfusion exceeding 2 units of red blood cell (OR, 1.599, 95% CI, 1.043-2.451, P = 0.035), and intensive care (OR, 1.817, 95% CI, 1.127-2.930, P = 0.014) were identified to be the independent predictors of the development of postoperative delirium. The risk of postoperative delirium increased with the increasing risk score of predictive nomogram, and the C-index was 0.67 (0.62 - 0.72). The calibration showed that the predicted probabilities of delirium in the predictive nomogram were close to the observed frequency of delirium, and the decision curve analysis confirmed the clinical utility of the nomogram when the threshold probabilities were between 8% and 35% due to the net benefit.