Prognostic model for delirium after cardiac surgery: insights from a surgical intensive care unit in a tertiary heart center

Abstract

Background: Postoperative delirium complicates up to one-quarter of cardiac surgery patients and increases morbidity and mortality. In this study, we determine the incidence and risk factors of postoperative delirium after cardiac surgery and develop and internally validate a multivariable risk prediction model for postoperative delirium.

Methods: In this prospective observational study, 158 adults undergoing cardiac surgery were enrolled. Delirium was assessed daily for five days using CAM-ICU, RASS, and ICDSC. Univariate predictors (P < 0.05) entered multivariate logistic regression. Model discrimination was assessed by ROC analysis; internal validity by 500-sample bootstrapping and ten-fold cross-validation.

Results: The mean of age was 60.4 ± 10.8 years and 53.2% wass female. Delirium occurred in 38 patients (24.1%), peaking on day 1 (15.2%), with hyperactive subtype in 91.7%. Univariate risk factors: female gender (73.7% vs 15.6%, P = 0.004), minimally invasive surgery (44.2% vs 20.0%, P < 0.001), mechanical ventilation (36.7±34.3 vs 28.7±20.9 h, P = 0.002), sedation (32.3±31.7 vs 19.7±16.7 h, P < 0.001), propofol (25.9±20.1 vs 14.2±9.1 h, P < 0.001), infection (42.1% vs 24.2%, P = 0.033), stroke (18.4% vs 5.3%, P = 0.009). Multivariate independent predictors: Female gender (OR 2.68; P = 0.048; AUC 0.635; P = 0.012); Minimally invasive surgery (OR 4.14; P = 0.005; AUC 0.650; P = 0.005); Propofol duration per hour (OR 1.07; P = 0.011; AUC 0.747; P < 0.001); Postoperative infection (OR 3.45; P = 0.046; AUC 0.590; P = 0.096). Apparent model (female gender, minimally invasive surgery, propofol sedation duration, and postoperative infection) AUC was 0.828 (95% CI 0.759–0.897; P < 0.001). Bootstrap mean optimism was 0.038, yielding an optimism-corrected AUC of 0.790. Ten-fold cross-validation produced a mean AUC of 0.79 ± 0.04.

Conclusions: Postoperative delirium affects nearly one-quarter of cardiac surgery patients. A prognostic model including female gender, minimally invasive surgery, propofol sedation duration, and postoperative infection demonstrates robust discrimination (optimism-corrected AUC 0.790) and internal stability. Implementation may enable early risk stratification and optimization of sedation and infection-prevention protocols.

Keywords: Delirium; Cardiac Surgery; Prognostic Model

Citation: Hien NS, Thanh NV, Hanh HH, Pho DC. Prognostic model for delirium after cardiac surgery: insights from a surgical intensive care unit in a tertiary heart center. Anaesth. pain intensive care 2026;30(3):291-300. DOI: 10.35975/apic.v30i3.3163

Received: February 07, 2026; Revised: March 15, 2026; Accepted: March 15, 2026