The Observational Scale of Level of Arousal: A brief tool for assessing and monitoring level of arousal in patients with delirium outside the ICU.

Roanna Hall,Alasdair M J Maclullich,Antaine Stíobhairt,Mike Allerhand,Zoë Tieges

doi:10.1002/gps.5324

Roanna Hall, Alasdair M J Maclullich + Show 3 more

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https://doi.org/10.1002/gps.5324

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Abstract

Altered level of arousal, encompassing drowsiness and hypervigilance, affects at least 10% of acutely unwell patients. Existing scales provide limited coverage of milder changes in level of arousal. We devised the Observational Scale of Level of Arousal (OSLA) to enable more detailed arousal assessment. Here, we provide a preliminary case-control study of performance of the OSLA in assessing abnormal level of arousal associated with delirium outside the ICU. Hip fracture patients (N = 108, median age = 82 years) were assessed for delirium pre- and post-operatively using the Confusion Assessment Method and the Delirium Rating Scale-Revised-98. The OSLA has four graded items assessing eye opening, eye contact, posture, and movement (score range 0 [normal arousal]-15). We assessed the psychometric and diagnostic characteristics of the OSLA. Adjusted linear mixed effects models were used to explore responsiveness of the OSLA to within-patient change in delirium status. A total of 44 patients (40.7%) were diagnosed with delirium. OSLA scores were higher in delirium (pooled median = 3, InterQuartile Range [IQR] = 2-5) compared to no delirium (pooled median = 1, IQR = 1-2; P-values <.05 to <.001). The Area under the Receiver Operating Characteristic curve was 0.82 (95% Confidence Interval (CI) = 0.77-0.86). OSLA scores were responsive to change in delirium status (ß = -3.09. SE = 1.41, P < .03). This study provides preliminary evidence supporting use of the OSLA as an instrument for identifying abnormal level of arousal associated with delirium and monitoring this longitudinally. Further validation in larger cohorts with blinded raters is required. J Am Geriatr Soc 68:-, 2020.

Highlights

Delirium is a severe, acute neurocognitive disorder characterised by disturbances in attention, level of arousal and other mental functions
This study provides preliminary evidence supporting use of the OSLA as an instrument for identifying abnormal level of arousal associated with delirium and monitoring this longitudinally
The present study provides preliminary support for the utility of the OSLA as a brief, accurate instrument for measuring level of arousal in delirium

Summary

Introduction

Acute neurocognitive disorder characterised by disturbances in attention, level of arousal and other mental functions. It affects at least one in eight hospitalised older patients and is independently associated with multiple adverse outcomes.. Alterations in level of arousal are common in delirium, with many patients showing hypo- or hyperarousal.. The hypoactive subtype, characterised by drowsiness or somnolence, is the most common form of delirium.. The arousal component of delirium has been described variably in standard diagnostic criteria (Table 1). In DSM-5, severely reduced level of arousal precluding cognitive testing or interview but above the level of coma is considered to indicate severe inattention. Assessment of level of arousal is a core part of the evaluation of the features of delirium, and arousal measurements appear to be useful in clinical practice as a strong indicator of delirium.

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