Delirium assessment in neuro-critically ill patients: A validation study

TLDR: This work hypothesized that delirium screening would be feasible in patients with acute brain injury and aimed to validate and compare the Confusion Assessment Method for the ICU and the Intensive Care Delirium Screening Checklist against clinical International Classification of Diseases‐10 criteria as reference.

Abstract: Background Delirium is underinvestigated in the neuro-critically ill, although the harmful effect of delirium is well established in patients in medical and surgical intensive care units (ICU).To detect delirium, a valid tool is needed. We hypothesized that delirium screening would be feasible in patients with acute brain injury and we aimed to validate and compare the Confusion Assessment Method for the ICU and the Intensive Care Delirium Screening Checklist against clinical International Classification of Diseases-10 criteria as reference. Methods Nurses assessed delirium using the Confusion Assessment Method for the ICU and Intensive Care Delirium Screening Checklist in adult patients with acute brain injury admitted to the Neurointensive care unit (Neuro-ICU), Copenhagen University Hospital, if their Richmond agitation-sedation scale score was -2 or above. As the reference, a team of psychiatrist assessed patients using the International Classification of Diseases-10 criteria. Results We enrolled 74 patients, of whom 25 (34%) were deemed unable to assess by the psychiatrists, leaving 49 (66%) for final analysis. Sensitivity and specificity for the Confusion Assessment Method for the ICU was 59% (95% CI: 41-75) and 56% (95% CI: 32-78), respectively, and 85% (95% CI: 70-94) and 75% (95% CI: 51-92), respectively, for the Intensive Care Delirium Screening Checklist. Conclusions Our findings suggest that the Intensive Care Delirium Screening Checklist may be a valid tool and the Confusion Assessment Method for the ICU is less suitable for delirium detection for patients in the Neuro-ICU. In the neuro-critically ill, delirium screening is challenged by limited feasibility.

Figures

Table 3 Criterion validation of the CAM-ICU and ICDSC against ICD 10

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University of Southern Denmark
Delirium assessment in neuro-critically ill patients
A validation study
Krone Larsen, Laura; Frøkjær, Vibe G.; Stub Nielsen, Jette; Skrobik, Yoanna; Winkler,
Yvonne; Møller, Kirsten; Christin Petersen, Marian; Egerod, Ingrid Eugenie
Published in:
Acta Anaesthesiologica Scandinavica
DOI:
10.1111/aas.13270
Publication date:
2019
Document version:
Accepted manuscript
Citation for pulished version (APA):
Krone Larsen, L., Frøkjær, V. G., Stub Nielsen, J., Skrobik, Y., Winkler, Y., Møller, K., Christin Petersen, M., &
Egerod, I. E. (2019). Delirium assessment in neuro-critically ill patients: A validation study.
Acta
Anaesthesiologica Scandinavica
,
63
(3), 352-359. https://doi.org/10.1111/aas.13270
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MRS LAURA KRONE LARSEN (Orcid ID : 0000-0002-7797-7667)
Article type : Clinical investigation
Title: Delirium assessment in neuro-critically ill patients: a validation study
Running title: Delirium assessment in the Neuro-ICU
Authors
Laura Krone Larsen,
Kirsten Møller, Marian Petersen, Ingrid Egerod.
Vibe G. Frøkjær, Jette Stub Nielsen, Yoanna Skrobik, Yvonne Winkler
Corresponding author:
Laura Krone Larsen, Critical Care Nurse and PhD student at the Neurointensive Care Unit 2093,
Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen O, Denmark.
Phone: +45 2636 8507, fax: +45 35457553, E-mail: Laura.krone.larsen@regionh.dk
ORCID: 0000-0002-7797-7667
The study was conducted at the Neurointensive Care Unit, 2093, Rigshospitalet, Copenhagen
University Hospital, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen O, Denmark
.
Author Manuscript

2
This article is protected by copyright. All rights reserved
Word Count:
Conflicts of interest
The authors have no conflicts of interest to declare.
Abstract
Background: Delirium is under-investigated in the neuro-critically ill, although the harmful effect
of delirium is well established in patients in medical and surgical intensive care units (ICU) . To
detect delirium, a valid tool is needed. We hypothesized that delirium screening would be feasible
in patients with acute brain injury and we aimed to validate and compare the Confusion Assessment
Method for the ICU and the Intensive Care Delirium Screening Checklist against clinical
International Classification of Diseases-10 criteria as reference.
Methods: Nurses assessed delirium using the Confusion Assessment Method for the ICU and
Intensive Care Delirium Screening Checklist in adult patients with acute brain injury admitted to
the Neurointensive care unit (Neuro-ICU), Copenhagen University Hospital, if their Richmond
agitation-sedation scale score was minus 2 or above. As the reference, a team of psychiatrist
assessed patients using the International Classification of Diseases-10 criteria.
Results: We enrolled 74 patients, of whom 25 (34%) were deemed unable to assess by the
psychiatrists, leaving 49 (66%) for final analysis. Sensitivity and specificity for the Confusion
Assessment Method for the ICU was 59% (95% CI 41-75) and 56% (95% CI 32-78), respectively
and 85% (95% CI 70-94) and 75% (95% CI 51-92), respectively for the Intensive Care Delirium
Screening Checklist.
Conclusions: Our findings suggest that the Intensive Care Delirium Screening Checklist may be a
valid tool and the Confusion Assessment Method for the ICU is less suitable for delirium detection
for patients in the Neuro-ICU. In the neuro-critically ill, delirium screening is challenged by
limited feasibility.
Clinicaltrials.gov identifier no. NCT02594982
Author Manuscript

3
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Keywords: Delirium, acute brain injury, neurointensive care unit, Intensive Care Delirium
Screening Checklist (ICDSC), Confusion Assessment Method for the ICU (CAM-ICU),
International Classification of Diseases -10 (ICD-10).
Editorial Comment
Delirium is common among ICU patients and it is associated with unfavorable outcomes. To further
explore the pathophysiology behind delirium and to evaluate possible treatments, objective and
standardized means for diagnosis of delirium are needed. This study assessed several simplified
rating systems for diagnostic accuracy compared to psychiatrist performing an ICD-10 diagosis of
delirium in patients in a neurointensive care setting.
Introduction
Delirium detection using a valid screening tool, such as the Confusion Assessment Method
for the ICU (CAM-ICU) or the Intensive Care Delirium Screening Checklist (ICDSC), substitutes
clinical evaluation using diagnostic criteria in many ICU studies
1-4
.This pragmatic approach is
limited by confounders, such as sedation-related level of consciousness
5
, and may not apply to the
neuro-critically ill. Invoked barriers to screening patients in the neuro-ICU include considering
delirium as brain dysfunction on the encephalopathy continuum, and coma, aphasia, deafness, or
other neurologic communication barriers
6
Two commonly used instruments
.
7
, the Confusion Assessment Method for the ICU (CAM-
ICU)
8
and the Intensive Care Delirium Screening Checklist (ICDSC)
9
both assign one of the
following three ratings to patients: positive, negative, or unable to assess (UTA). In addition, the
ICDSC also differentiates between no delirium, subsyndromal delirium, and delirium
10
. The
original ICDSC validation study was performed on a mixed ICU population and included
neurologically critically ill
9
. A subsequent multicentre feasibility and reliability study in adult
patients in three Neuro-ICU´s showed feasibility and good concordance in 75% of all evaluations
11
.
By contrast, the original CAM-ICU validation study did not include patients with a neuro-critically
diagnosis
8
. A later study limited to patients with stroke reported that delirium as detected by the
Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV criteria was present in 42,6%; the
CAM-ICU had a sensitivity of 76% and a specificity of 98% compared to DSM-IV
12
. Included
patients had a nearly normal level of consciousness based on their median admission Glasgow
Coma Scale (GCS), 14.5
12
. In a recently published letter, the CAM-ICU and the ICDSC were
Author Manuscript

4
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compared in patients with mild and moderate traumatic brain injury (TBI), a median admission
GCS of 14, and a mean APACHE II score of 11.5 (+/- 6.4). The sensitivity and specificity was 62%
and 74% with the CAM-ICU and 64% and 79% with the ICDSC
13
The importance of delirium assessments in the ICU
. Thus, the current knowledge of
delirium in neuro-critically ill patients appears to be related to patients with relatively mild brain
dysfunction and with mild to moderate illness severity.
14
derive from its association with poor
outcomes such as length of stay, mortality, and cognitive impairment
15-19
. This has led to a broad
endorsement of the CAM-ICU and the ICDSC in critical care settings. Expert European Society of
Intensive Care Medicine panellists and the most recent Pain, Agitation and Delirium (PAD) Society
of Critical Care Medicine guidelines strongly recommend the use of delirium screening using the
two instruments
3,20
. Yet, no study has validated delirium screening in a mixed Neuro-ICU
population. Rigorous delirium screening tool validation and comparisons, that consider feasibility
and cofounders as level of consciousness, are necessary in this vulnerable population to ensure
scientifically grounded ’diagnosis- equivalents’ before considering prevention, treatment and
outcome studies. Accordingly, we prospectively evaluated patients with acute brain injury;
traumatic and non-traumatic injuries, using the International Classification of Diseases (ICD)-10 as
reference. We hypothesized that the neuro-critically ill are assessable for delirium and we aimed to
evaluate and compare the validity of the CAM-ICU and the ICDSC for delirium assessment in
patients with acute brain injury using the ICD-10 criteria as reference.
METHODS
Site and Setting
This prospective single-centre study was conducted at Copenhagen University Hospital, a 1300 bed
tertiary referral hospital covering a catchment area of 2.6 million citizens in eastern Denmark.
Participants
From August 15
th
, 2015 to June 30
th
, 2016 all admitted adult patients in the Neuro-ICU with acute
brain injury from TBI or ischemic or haemorrhagic stroke with an anticipated stay of 48 hours or
more were included. We excluded patients with pre-existing severe brain injury, children, and
patients whose therapeutic aim was palliative care.
Sample size
Author Manuscript

Frequently asked questions

Q1. What contributions have the authors mentioned in the paper "University of southern denmark delirium assessment in neuro-critically ill patients a validation study" ?

In this paper, the authors evaluated the validity of the Confusion Assessment Method for the ICU ( CAM-ICU ) and the Intensive Care Delirium Screening Checklist ( ICDSC ) for delirium assessment in patients with acute brain injury using the ICD-10 criteria as reference. 

Q2. What have the authors stated for future works in "University of southern denmark delirium assessment in neuro-critically ill patients a validation study" ?

Future studies are also recommended to investigate prevention, treatment, and long-term outcomes as well as exploring the patient experience. 

Q3. What is the importance of delirium screening in critical care?

Rigorous delirium screening tool validation and comparisons, that consider feasibility and cofounders as level of consciousness, are necessary in this vulnerable population to ensure scientifically grounded ’diagnosis- equivalents’ before considering prevention, treatment and outcome studies. 

Q4. What are the future studies recommended to investigate?

Future studies are also recommended to investigate prevention, treatment, and long-term outcomes as well as exploring the patient experience. 

Q5. What were the reasons for evaluating as UTA?

Reasons given by psychiatrists for evaluating as UTA were low level of arousal at time of assessment (N=15), inability to communicate (verbally or non-verbally) (N=9), or insufficient information in the hospital chart (N=1). 

Q6. What is the way to detect delirium?

Delirium detection using a valid screening tool, such as the Confusion Assessment Methodfor the ICU (CAM-ICU) or the Intensive Care Delirium Screening Checklist (ICDSC), substitutes clinical evaluation using diagnostic criteria in many ICU studies 1-4. 

Q7. How many patients were deemed unable to assess by the psychiatrists?

The authors enrolled 74 patients, of whom 25 (34%) were deemed unable to assess by the psychiatrists, leaving 49 (66%) for final analysis. 

Q8. What criteria were used to assess delirium in patients with acute brain injury?

A team consisting of one consultant psychiatrist and three physicians undergoing advanced specialist training in clinical psychiatry (hereafter termed psychiatrists) conducted the delirium assessment using ICD-10 criteria on the day that the patient first became assessable, defined as a best Richmond agitation-sedation scale (RASS) 21 score of minus 2 or above. 

Q9. What are the common barriers to delirium screening?

Invoked barriers to screening patients in the neuro-ICU include considering delirium as brain dysfunction on the encephalopathy continuum, and coma, aphasia, deafness, or other neurologic communication barriers6Two commonly used instruments . 

Q10. How many patients with GCS 10 were assessable?

Seven of seventeen (41%) patients with GCS 10 were assessable, while two of twenty (10%) patients with GCS 14 remained unassessable (Appendix 2). 

Q11. Why did the CAM-ICU group have a higher percentage of patients with TBI?

psychiatrists using the ICD-10 considered a large proportion of patients successfully evaluated with the ICDSC/CAM-ICU as UTA, perhaps because of level of consciousness fluctuations. 

Q12. What is the way to diagnose delirium?

Their findings suggest that the Intensive Care Delirium Screening Checklist may be a valid tool and the Confusion Assessment Method for the ICU is less suitable for delirium detection for patients in the Neuro-ICU. 

Q13. What is the reason for the ICD-10 study?

The study suggests that the ICDSC is a valid tool to detect delirium in patients with acute brain injury in the Neuro-ICU, whereas the CAM-ICU is less valid .