Independent External Validation of a Preoperative Prediction Model for Delirium After Cardiac Surgery: A Prospective Observational Cohort Study

J Cardiothorac Vasc Anesth. 2023 Mar;37(3):415-422. doi: 10.1053/j.jvca.2022.11.038. Epub 2022 Dec 6.

Abstract

Objective: This investigation provided independent external validation of an existing preoperative risk prediction model.

Design: A prospective observational cohort study of patients undergoing cardiac surgery covering the period between April 16, 2018 and January 18, 2022.

Setting: Two academic hospitals in Switzerland.

Participants: Adult patients (≥60 years of age) who underwent elective cardiac surgery, including coronary artery bypass graft, mitral or aortic valve replacement or repair, and combined procedures.

Interventions: None.

Measurements and main results: The primary outcome measure was the incidence of postoperative delirium (POD) in the intensive or intermediate care unit, diagnosed using the Intensive Care Delirium Screening Checklist. The prediction model contained 4 preoperative risk factors to which the following points were assigned: Mini-Mental State Examination (MMSE) score ≤23 received 2 points; MMSE 24-27, Geriatric Depression Scale (GDS) >4, prior stroke and/or transient ischemic attack (TIA), and abnormal serum albumin (≤3.5 or ≥4.5 g/dL) received 1 point each. The missing data were handled using multiple imputation. In total, 348 patients were included in the study. Sixty patients (17.4%) developed POD. For point levels in the prediction model of 0, 1, 2, and ≥3, the cumulative incidence of POD was 12.6%, 22.8%, 25.8%, and 35%, respectively. The validation resulted in a pooled area under the receiver operating characteristics curve of 0.60 (median CI, 0.525-0.679).

Conclusions: The evaluated predictive model for delirium after cardiac surgery in this patient cohort showed only poor discriminative capacity but fair calibration.

Keywords: External validation; cardiac surgery; delirium; prediction.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Cardiac Surgical Procedures* / adverse effects
  • Coronary Artery Bypass / adverse effects
  • Delirium* / diagnosis
  • Delirium* / epidemiology
  • Delirium* / etiology
  • Emergence Delirium* / diagnosis
  • Emergence Delirium* / epidemiology
  • Emergence Delirium* / etiology
  • Humans
  • Postoperative Complications / diagnosis
  • Postoperative Complications / epidemiology
  • Postoperative Complications / etiology
  • Prospective Studies
  • Risk Factors