The Diagnostic Performance of the Richmond Agitation Sedation Scale for Detecting Delirium in Older Emergency Department Patients

Abstract

Objectives Delirium is frequently missed in older emergency department (ED) patients. Brief (<2 minutes) delirium assessments have been validated for the ED, but some ED health care providers may consider them to be cumbersome. The Richmond Agitation Sedation Scale (RASS) is an observational scale that quantifies level of consciousness and takes less than 10 seconds to perform. The authors sought to explore the diagnostic accuracy of the RASS for delirium in older ED patients. Methods This was a preplanned analysis of a prospective observational study designed to validate brief delirium assessments for the ED. The study was conducted at an academic ED and enrolled patients who were 65 years or older. Patients who were non-English speaking, deaf, blind, comatose, or had end-stage dementia were excluded. A research assistant (RA) and a physician performed the RASS at the time of enrollment. Within 3 hours, a consultation-liaison psychiatrist performed his or her comprehensive reference standard assessment for delirium using Diagnostic and Statistical Manual of Mental Disorders Fourth Edition, Text Revision (DSM-IV-TR) criteria. Sensitivities, specificities, and likelihood ratios with their 95% confidence intervals (CIs) were calculated. Results Of 406 enrolled patients, 50 (12.3%) had delirium diagnosed by the consult-liaison psychiatrist reference rater. When performed by the RA, a RASS other than 0 (RASS > 0 or < 0) was 84.0% sensitive (95% CI = 73.8% to 94.2%), and 87.6% specific (95% CI = 84.2% to 91.1%) for delirium. When performed by physician, a RASS other than 0 was 82.0% sensitive (95% CI = 71.4% to 92.6%) and 85.1% specific (95% CI = 81.4% to 88.8%) for delirium. Using a RASS > +1 or < −1 as the cut-off, the specificity improved to approximately 99% for both raters at the expense of sensitivity; the sensitivities were 22.0% (95% CI = 10.5% to 33.5%) and 16.0% (95% CI = 5.8% to 25.2%) in the RAs and physician raters, respectively. The positive likelihood ratio was 19.6 (95% CI = 6.5 to 59.1) when performed by the RA, and 57.0 (95% CI = 7.3 to 445.9) when performed by the physician, indicating that a RASS > +1 or < −1 strongly increased the likelihood of delirium. The weighted kappa was 0.63, indicating moderate interobserver reliability. Conclusions In older ED patients, a RASS other than 0 has very good sensitivity and specificity for delirium as diagnosed by a psychiatrist. A RASS > +1 or < −1 is nearly diagnostic for delirium given the very high positive likelihood ratio.

Delirium as a marker of vulnerability in the elderly

“…Inouye has shown that the presence of sensory impairment, dementia, older age and the hypokinetic variant of delirium increase the odds of delirium to be undetected by nurses. 17 In this study, the simple clinical observation, without using standardized diagnostic tools led to a rate of underecognition which was around 70%, significantly lower if compared to the rate of delirium detected by a team of researchers trained in the use of diagnostic tools. 17 However, also untrained physicians tend to frequently overlook delirium.…”

“…17 In this study, the simple clinical observation, without using standardized diagnostic tools led to a rate of underecognition which was around 70%, significantly lower if compared to the rate of delirium detected by a team of researchers trained in the use of diagnostic tools. 17 However, also untrained physicians tend to frequently overlook delirium. 51 There are more than twenty-four diagnostic tools for delirium, the most commonly used is the confusion assessment method (CAM).…”

“…Here, the prevalence of delirium ranges from 9.6 to 12.3%, according to different studies. [16][17][18][19] Delirium is associated with a number of adverse clinical outcomes, including increased risk of institutionalization and higher mortality. 12,20,21 In hospital settings, delirium is associated with a nearly double risk of death at 2 years follow-up, independent of important confounders, such as age, sex, comorbidity and dementia.…”

Detecting Delirium Superimposed on Dementia: Evaluation of the Diagnostic Performance of the Richmond Agitation and Sedation Scale

“…11–13 However, none of the previous studies has focused specifically on patients with delirium and dementia. Han and colleagues 12 found a RASS score other than 0 to have a very good sensitivity (84%, 95% CI: 73.8% to 94.2%) and specificity (87.6%, 95 % CI: 84.2% to 91.1%) for the detection of delirium in 406 older patients admitted to an emergency department (ED). Interestingly, a RASS score > +1 or < –1 was nearly diagnostic for delirium in this population, 12 providing the busy ED setting with a fast and valuable tool for the screening-diagnosis of delirium.…”

“…12 In this group were included older patients admitted to an academic, tertiary care emergency department July 2009 to February 2012. Delirium was diagnosed using a comprehensive consultation-liaison psychiatrist assessment with the DSM-IV-TR criteria, while dementia was ascertained using the clinical records and IQCODE.…”