Predicting delirium after vascular surgery: a model based on pre- and intraoperative data

Abstract

Objective: The aim of the study was to determine pre- and intraoperative risk factors for the development of postoperative delirium among patients undergoing aortic, carotid, and peripheral vascular surgery to predict the risk for postoperative delirium.

Summary background data: Although postoperative delirium after vascular surgery is a frequent complication and is associated with the need for more inpatient hospital care and longer length of hospital stay, little is known about risk factors for delirium in patients undergoing vascular surgery.

Methods: Pre-, intra-, and postoperative data were prospectively collected, including the first 7 postoperative days with daily follow-up by a surgeon and a psychiatrist of 153 patients undergoing elective vascular surgery. Delirium (Diagnostic and statistical Manual of Mental Disorders IV) was diagnosed by the psychiatrist. Multivariate linear logistic regression and a cross validation analysis were performed to find a set of parameters to predict postoperative delirium.

Results: Sixty patients (39.2%) developed postoperative delirium. The best set of predictors included the absence of supraaortic occlusive disease and hypercholesterinemia, history of a major amputation, age over 65 years, a body size of less than 170 cm, preoperative psychiatric parameters and intraoperative parameters correlated to increased blood loss. The combination of these parameters allows the estimation of an individual patients' risk for postoperative delirium already at the end of vascular surgery with an overall accuracy of 69.9%.

Conclusions: Postoperative delirium after vascular surgery is a frequent complication. A model based on pre- and intraoperative somatic and psychiatric risk factors allows prediction of the patient's risk for developing postoperative delirium.

Figures

FIGURE 1. ROC curve for the final prediction model. The cut-off points 5.5 and 7.1 were arbitrarily chosen as examples for high- and low-risk groups (see Fig. 2).

FIGURE 2. Mean score values ± SD of patients with and without postoperative delirium. The maximal score value is 15.63; however, no patient achieved more than 11.67 points.