Construction of an online nomogram of risk factors for postoperative delirium in elderly patients with hip fracture / 中华创伤骨科杂志

ABSTRACT

Objective:To investigate the risk factors for postoperative delirium in the elderly patients with hip fracture and to construct an online nomogram of the risk factors.Methods:Retrospectively analyzed were the data of 483 elderly patients with hip fracture who had been treated with artificial joint replacement from May 2020 to August 2021 at Department of Orthopaedics (Department of Joint Surgery), Jinling Hospital Affiliated to Medical College of Nanjing University. There were 166 males and 317 females, aged from 61 to 99 years (average, 82.1 years). Fracture types 333 femoral neck fractures and 150 intertrochanteric fractures. The patients were divided into a delirium group ( n=149) and a delirium-free group ( n=334) according to whether postoperative delirium occurred after surgery. The 2 groups were compared in terms of general data like age, gender, body mass index, and concomitant diseases, as well as in terms of indexes like pre-operative albumin, preoperative hemoglobin, and postoperative C-reactive protein (CRP). Factors with P < 0.05 were included in the multi-factor logistic regression analysis to screen out the risk factors for postoperative delirium. The "rms" package of R software was used to draw the nomogram; the Bootstrap method was used to repeat the sampling 1,000 times for evaluation, calculation of the consistency index ( CI), and drawing of the ROC curve and correction curve; the decision curve was plotted using the "rmda" package. Results:There were significant differences between the delirium group and the delirium-free group in age, preoperative anxiety, Alzheimer＇s disease, history of cerebrovascular disease, preoperative albumin, intraoperative hypotension and postoperative CRP ( P < 0.05). The multifactorial logistic regression analysis showed that high age, preoperative anxiety, Alzheimer＇s disease, preoperative albumin < 35 g/L, and postoperative CRP ≥90 mg/L were the risk factors for postoperative delirium in the elderly patients with hip fracture after artificial joint replacement ( P < 0.05). The area under the ROC curve of the nomogram constructed by incorporating the risk factors for postoperative delirium was 0.894 (95% CI 0.865 to 0.923) with a CI of 0.889; the calibration curve showed that the calibration curve of this nomogram model tended to be close to the ideal curve. The decision curve analysis showed that the threshold value was 0.01 to 1.00, showing the net benefit rate of this nomogram model > 0 when used to predict the postoperative delirium in the elderly patients with hip fracture. Conclusions:High age, preoperative anxiety, Alzheimer's disease, preoperative albumin < 35 g/L, and postoperative CRP ≥90 mg/L may be the risk factors for postoperative delirium in the elderly patients with hip fracture after artificial joint replacement. The online nomogram based on these factors demonstrates a good value in prediction of postoperative delirium.