The Validity and Applicability of the Revised Delirium Rating Scale (DRS-R98) for Delirium Severity Assessment in a Critical Care Setting

Eiman Saeed Almuhairi; Monica Badejo; Aneesa Peer; Mervi Pitkanen; Cathrine A McKenzie

doi:10.1177/08850666231199986

The Validity and Applicability of the Revised Delirium Rating Scale (DRS-R98) for Delirium Severity Assessment in a Critical Care Setting

J Intensive Care Med. 2024 Mar;39(3):240-249. doi: 10.1177/08850666231199986. Epub 2023 Sep 5.

Authors

Eiman Saeed Almuhairi¹, Monica Badejo², Aneesa Peer³, Mervi Pitkanen^{1

4}, Cathrine A McKenzie^{1

4

5

6

7}

Affiliations

¹ Institute of Pharmaceutical Sciences, School of Cancer and Pharmacy, King's College, London, UK.
² Department of Social, Therapeutic and Community Studies, Goldsmiths College, University of London, London, UK.
³ Lambeth Southeast Focussed Support, Clozapine Plus Service, Orchard House - Lambeth Hospital, London, UK.
⁴ Department of Neuropsychiatry, South London and Maudsley NHS Foundation Trust, Maudsley Hospital, London, UK.
⁵ Department of Pharmacy and Critical Care, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
⁶ School of Medicine, University of Southampton, National Institute of Health and Care Research (NIHR), Southampton Biomedical Research Centre, Perioperative and Critical Care Theme, Southampton, UK.
⁷ NIHR Applied Research Collaborative Wessex, Southampton, UK.

Abstract

Background: Delirium is a neuropsychiatric syndrome common in critical illness. Worsening delirium severity is associated with poorer clinical outcomes, yet its assessment remains under-reported with most severity assessment tools not validated for critical care. The DRS-R98 is a widely applied and validated tool. The aim of this project is to report the validation and utility of the DRS-R98 in critical illness.

Methods: This prospective, cohort study was conducted in adults with delirium admitted to a critical care unit and predicted to stay for ≥ 24 h. We excluded patients with severe neurological or communication barriers that would have interfered with the DRS-R98 assessment. Patients were screened using a delirium detection algorithm and the Confusion Assessment Method for the Intensive Care Unit. Eligible patient informations were collected and reported to qualified assessor/s before visiting clinical areas, confirming delirium presence and undertaking DRS- R98 assessments. To assess the tool's construct validity, an intensivist completed the Clinical Global Impression-Scale (CGI-S). To calculate the inter-rater reliability (IRR) a subset of patients were simultaneously evaluated by two assessors.

Results: We assessed 22 patients, 73% were male, with a median age of 65 years (IQR14). The DRS -R98 mean (SD) severity score was 24 (+/-7.7), total scale was 29 (+/18.0), and CGI-S 3.5 (+/11.5). Assessment duration was 90 min (+/-55) and 15 min (+/-5) for record data extraction and clinical assessment respectively. The CGI-S significantly correlated with DRS-R98 severity (r = 0.626) and total (r = 0.628) scales. The DRS-R98 Cronbach's alpha was 0.896 for severity scale and 0.886 for total scale. The inter-rater reliability (IRR) was assessed in six patients and reported an inter-correlation coefficient of 0.505 (p = 0.124) and 0.565 (p = 0.93) for the severity and total scale respectively.

Conclusions: In critical care, the Delirium Rating Scale R98 had good construct validity, excellent internal consistency, and moderate inter-rater reliability.

Keywords: critical care; delirium; intensive care; severity; validation.

MeSH terms

Adolescent
Adult
Cohort Studies
Critical Care
Critical Illness
Delirium* / diagnosis
Female
Humans
Male
Prospective Studies
Psychiatric Status Rating Scales
Reproducibility of Results
Severity of Illness Index