Delirium evaluation in patients in the ICU requires the use of an arousal/sedation assessment tool prior to assessing consciousness. The Richmond Agitation-Sedation Scale (RASS) and the Riker Sedation-Agitation Scale (SAS) are well-validated arousal/sedation tools. We sought to assess the concordance of RASS and SAS assessments in determining eligibility of patients in the ICU for delirium screening using the confusion assessment method for the ICU (CAM-ICU).
We performed a prospective cohort study in the adult medical, surgical, and progressive (step-down) ICUs of a tertiary care, university-affiliated, urban hospital in Indianapolis, Indiana. The cohort included 975 admissions to the ICU between January and October 2009.
The outcome measures of interest were the correlation and agreement between RASS and SAS measurements. In 2,469 RASS and SAS paired screens, the rank correlation using the Spearman correlation coefficient was 0.91, and the agreement between the two screening tools for assessing CAM-ICU eligibility as estimated by the κ coefficient was 0.93. Analysis showed that 70.1% of screens were eligible for CAM-ICU assessment using RASS (7.1% sedated [RASS −3 to −1]; 62.6% calm ; and 0.4% restless, agitated [+1 to +3]), compared with 72.1% using SAS (5% sedated [SAS 3]; 66.5% calm ; and 0.6% anxious, agitated [5, 6]). In the mechanically ventilated subgroup, RASS identified 19.1% CAM-ICU eligible patients compared with 24.6% by SAS. The correlation coefficient in this subgroup was 0.70 and the agreement was 0.81.
Both SAS and RASS led to similar rates of delirium assessment using the CAM-ICU.