New consciousness scale for delirium



    A new tool for assessing level of consciousness may improve the diagnosis of delirium. We have translated the Observational Scale of Level of Arousal (OSLA) into Norwegian and will use it in clinical practice and research.

    Delirium, or ‘acute confusional state’, occurs frequently in acute somatic disease, especially in elderly patients. The condition is associated with poor prognosis and an increased strain on the patient, their next of kin and the health service. Delirium is characterised by acute changes in level of consciousness, attention and cognition, often accompanied by perceptual disturbances and an altered sleep/wake cycle. The condition tends to have a fluctuating course, should not be attributable to an existing cognitive disorder (e.g., dementia), and should be a direct physiological consequence of another medical condition (1, 2). Delirium often goes undiagnosed if one relies on subjective diagnosis, clinical intuition and doctors’ and nurses’ individual experience. The hypoactive variant in particular, with impaired psychomotor speed, lack of initiative, and somnolence, is often mistaken for depression or dementia. The most commonly used diagnostic aid is the Confusion Assessment Method (CAM). However, in recent years, a number of other tools have been developed for diagnosis and assessment of patients with delirium.

    Observational scale for level of consciousness

    Observational scale for level of consciousness

    The Observational Scale of Level of Arousal (OSLA) is a new, short scale for measuring level of consciousness in patients with delirium (3). It was drawn up by geriatricians at the University of Edinburgh and is meant to supplement other consciousness scales, such as the Glasgow Coma Scale (GCS) or the Richmond Agitation-Sedation Scale (RASS). These capture the variation and changes seen in delirium to a lesser degree.

    The OSLA-form is completed after having seen the patient, and takes little time (approximately one minute). Assessment is based on observations of the patient and does not require him/her to be able to respond verbally. The scale covers four clinical areas: eye opening, eye contact, posture and movement. Higher scores indicate an abnormal level of consciousness. The total score (0 – 15) is calculated by adding together points from each category.

    Changes in level of consciousness are associated with delirium

    Changes in level of consciousness are associated with delirium

    Acute changes in level of consciousness, assessed using OSLA, are strongly associated with delirium and its severity (3). Demonstrating an altered level of consciousness can increase diagnostic awareness and increase the likelihood of a delirium diagnosis.

    We translated the Observational Scale of Level of Arousal from English to Norwegian as follows: First, one person translated the text from English to Norwegian. The Norwegian text was then translated back into English by a bilingual (English and Norwegian) doctor with clinical experience of geriatric medicine and delirium. Finally, the back-translated English version was compared with the original, and weaknesses in the Norwegian version were discussed and amended. In the near future, we will validate the Norwegian version of the scale in a study of drug interventions in delirium. The study is planned to begin in Spring 2014 in the Department of Geriatric Medicine, Oslo University Hospital. The Norwegian translation of OSLA is available on the Norwegian Geriatrics Society website (4).


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