Delirium screening in critically ill patients: a systematic review and meta-analysis.

OBJECTIVE: Despite its frequency and impact, delirium in critically ill patients is poorly recognized. Our aim was to systematically review the accuracy of delirium screening instruments in critically ill patients. DATA SOURCE: Systematic review and meta-analysis of publications between 1966 and 2011. The Medline and Embase databases were searched for studies on delirium in critically ill patients. STUDY SELECTION: The meta-analysis was limited to studies in critically ill patients in intensive care units, surgical wards, or emergency rooms. The delirium screening tool had to be feasible in a clinical setting for use by a nonexpert. As the gold standard, delirium had to be diagnosed based on appropriate criteria by a delirium expert. DATA EXTRACTION: The outcomes assessed were sensitivity, specificity, likelihood ratios, and summary receiver operating characteristics curves. DATA SYNTHESIS: Sixteen studies covering 1,523 participants and five screening tools were included in the systematic review. The pooled sensitivities and specificities of Confusion Assessment Method for the Intensive Care Unit for detection of delirium in critically ill patients were 75.5% and 95.8%, and for Intensive Care Delirium Screening Checklist 80.1% and 74.6%, respectively. All but one study was performed in a research setting, and that one study suggested that with routine use of the Confusion Assessment Method for the Intensive Care Unit, half of the patients with delirium were not detected.
CONCLUSIONS: The Confusion Assessment Method for the Intensive Care Unit was the most specific bedside tool for the assessment of delirium in critically ill patients. However, there was significant heterogeneity of the results. These findings were largely obtained in research settings, and the low sensitivity of the Confusion Assessment Method for the Intensive Care Unit in routine, daily practice may limit its use as a screening test.