Derivation and validation of a prediction rule for sedative-associated delirium during acute respiratory failure requiring mechanical ventilation

BackgroundDelirium during acute respiratory failure is common and morbid. Pharmacologic sedation is a major risk factor for delirium, but some sedation is often necessary for the provision of safe care of mechanically ventilated patients. A simple, transparent model that predicts sedative-associated delirium in mechanically ventilated ICU patients could be used to guide decisions about personalized sedation. Research QuestionCan the risk of sedative-associated delirium be estimated in mechanically-ventilated ICU patients? Study Design and MethodsUsing the subset of patients in a previously-published ICU cohort who received mechanical ventilation, we performed backward stepwise logistic regression to derive a model predictive of sedative-associated delirium. We validated this model internally using hundredfold bootstrapping. We then validated this model externally in a separate prospective cohort of mechanically ventilated ICU patients. Results836 patients comprised the derivation cohort. Backwards stepwise regression produced a model with age, BMI, sepsis, SOFA, malignancy, COPD, stroke, sex, and doses of sedatives (opioids, propofol, and/or benzodiazepines) as predictors of sedative-associated delirium. The model had very good discriminative power, with an area under the receiver-operator curve (AUROC) of 0.83. Internal validation via bootstrapping showed preserved discriminatory function with an AUROC of 0.81 and graphical evidence of good calibration. External validation in a separate set of 340 patients showed good discrimination, with AUROC of 0.70. InterpretationSedative-associated delirium during acute respiratory failure requiring mechanical ventilation can be predicted using a simple, transparent model, which can now be validated in a prospective study.