Influence of Sedation Level and Ventilation Status on the Diagnostic Validity of Delirium Screening Tools in the ICU-An International, Prospective, Bi-Center Observational Study (IDeAS).

Background and objectives: The use of delirium screening instruments (DSIs) is recommended in critical care practice for a timely detection of delirium. We hypothesize that the patient-related factors "level of sedation" and "mechanical ventilation" impact test validity of DSIs. Materials and Methods: This is a prospective, bi-center observational study (clinicaltrials.gov: NCT01720914). Critically ill patients were screened for delirium daily for up to seven days after enrollment using the Nursing Delirium Screening Scale (Nu-DESC), Intensive Care Delirium Screening Checklist (ICDSC), and Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Reference standard for delirium diagnosis was the neuropsychiatric examination using the criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). Immediately before delirium assessment, ventilation status and sedation levels were documented. Results: 160 patients were enrolled and 151 patients went into final analysis. Delirium incidence was 23.2%. Nu-DESC showed a sensitivity and specificity of 88.5%, a positive predictive value (PPV) of 71.9%, and a negative predictive value (NPV) of 95.8%. ICDSC had a sensitivity of 62.5%, a specificity of 92.4%, a PPV of 71.4%, and a NPV of 89.0%. CAM-ICU showed a sensitivity of 75.0%, a specificity of 94.7%, a PPV of 85.7%, and a NPV of 90.0%. For Nu-DESC and ICDSC, test validity was significantly better for non-sedated patients (Richmond Agitation Sedation Scale (RASS) 0/-1), whereas test validity for CAM-ICU in a severity scale version showed no significant differences for different sedation levels. No DSI showed a significant difference in test validity between noninvasively and invasively ventilated patients. Conclusions: Test validities of DSIs were comparable to previous studies. The observational scores ICDSC and Nu-DESC showed a significantly better performance in awake and drowsy patients (RASS 0/-1) when compared with other sedation levels. Physicians should refrain from sedation whenever possible to avoid suboptimal performance of DSIs.

Different assessment tools for intensive care unit delirium: which score to use?

OBJECTIVE: To compare validity and reliability of three instruments for detection and assessment of delirium in intensive care unit (ICU) patients. Delirium in critically ill patients is associated with higher mortality, prolonged duration of ICU stay, and greater healthcare costs. Currently, there are several assessment tools available for detection of delirium, but only a few of these assessment systems are developed specifically to screen for delirium in ICU patients. DESIGN: Prospective cohort study. SETTING: ICU at a university hospital. PATIENTS: A total of 156 surgical patients aged > or = 60 yrs consecutively admitted to the ICU, with a length of stay of at least 24 hrs. MEASUREMENTS AND MAIN RESULTS: This study was approved by the institutional ethics committee. Trained staff members performed daily and independently the Confusion Assessment Method for the ICU (CAM-ICU), the Nursing Delirium Screening Scale (Nu-DESC), and the Delirium Detection Score (DDS). These evaluations were compared against the reference standard conducted by a delirium expert (blinded to the study), who used delirium criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Of 156 patients, 63 (40%) were identified as delirious by the reference standard during the study. Using the CAM-ICU and the Nu-DESC, we measured comparable sensitivities (CAM-ICU, 81%; Nu-DESC, 83%). The specificity of the CAM-ICU was significantly higher than that of the Nu-DESC (96% vs. 81%, p < .01). In contrast, the DDS showed poor sensitivity (30%), whereas the specificity was significantly higher compared with the Nu-DESC (DDS, 91%; Nu-DESC, 81%, p < .05). The interrater reliability was "almost perfect" for the CAM-ICU (kappa = 0.89) and "substantial" for DDS and Nu-DESC (kappa = 0.79, 0.68). CONCLUSION: The CAM-ICU showed the best validity of the evaluated scales to identify delirium in ICU patients. The Nu-DESC might be an alternative tool for detection of ICU delirium. The DDS should not be used as a screening tool.