title: Risk prediction models for delirium in the intensive care unit after cardiac surgery: a systematic review and independent external validation.
abstract: Numerous risk prediction models are available for predicting delirium after cardiac surgery, but few have been directly compared with one another or been validated in an independent data set. We conducted a systematic review to identify validated risk prediction models of delirium (using the Confusion Assessment Method-Intensive Care Unit tool) after cardiac surgery and assessed the transportability of the risk prediction models on a prospective cohort of 600 consecutive patients undergoing cardiac surgery at a university hospital in Hong Kong from July 2013 to July 2015. The discrimination (c-statistic), calibration (GiViTI calibration belt), and clinical usefulness (decision curve analysis) of the risk prediction models were examined in a stepwise manner. Three published high-quality intensive care unit delirium risk prediction models (n=5939) were identified: Katznelson, the original PRE-DELIRIC, and the international recalibrated PRE-DELIRIC model. Delirium occurred in 83 patients (13.8%, 95% CI: 11.2-16.9%). After updating the intercept and regression coefficients in the Katznelson model, there was fair discrimination (0.62, 95% CI: 0.58-0.66) and good calibration. As the original PRE-DELIRIC model was already validated externally and recalibrated in six countries, we performed a logistic calibration on the recalibrated model and found acceptable discrimination (0.75, 95% CI: 0.72-0.79) and good calibration. Decision curve analysis demonstrated that the recalibrated PRE-DELIRIC risk model was marginally more clinically useful than the Katznelson model. Current models predict delirium risk in the intensive care unit after cardiac surgery with only fair to moderate accuracy and are insufficient for routine clinical use.
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: A
authors.initials: A
authors.lastname: Lee
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: J L
authors.initials: JL
authors.lastname: Mu
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: G M
authors.initials: GM
authors.lastname: Joynt
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: C H
authors.initials: CH
authors.lastname: Chiu
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: V K W
authors.initials: VKW
authors.lastname: Lai
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: T
authors.initials: T
authors.lastname: Gin
authors.affiliation: Division of Cardiothoracic Surgery, Department of Surgery, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: M J
authors.initials: MJ
authors.lastname: Underwood
mesh_terms: D018806:APACHE; D006348:Cardiac Surgical Procedures; D003661:Decision Support Techniques; D003693:Delirium / Q000175:diagnosis* / Q000517:prevention & control; D006723:Hong Kong; D006801:Humans; D007362:Intensive Care Units; D007902:Length of Stay; D015203:Reproducibility of Results; D012307:Risk Factors
keywords: cardiac surgical procedures; decision support techniques; delirium; postoperative complications; review; systematic; validation studies