Phenomenology in Delirium

The featured paper is ‘Phenomenology of delirium. Assessment of 100 adult cases using standardised measures’ by D Meagher and colleagues.  One of the authors is employed by Eli Lilly as stated in the declaration of interests section although I couldn’t immediately see any stated pharmacological connections with the area of study. The authors start by discussing the lack of research into the phenomenology of delirium with validated instruments as well as discussing two such instruments –  ‘The Cognitive Test for Delirium’ and ‘The Delirium Rating Scale Revised 98’. What was interesting about the DRS-R98 was that it can apparently distinguish between delirium and dementia.

The aim of the study was to characterise the phenomenology in delirium and particularly examine the ‘primacy of inattention’. The authors selected patients from Palliative care over 2 years and looked at their symptoms at one point in time – thus this is a cross-sectional study. Cases for inclusion were identified by the treating team. There may have been some selection bias towards those who were disorientated. DSM-V criteria were wused with ‘acceptable interperson reliability’ of the assessors (although we don’t know what this is). Patients were then administered the RS-R98 followed by the CTD. One interesting feature of the study was that consent was gained from relatives or carers in people who lacked capacity. People recruited into the study were administered the two delirium rating scales. Scores of severity were obtained by using the gradings on the CTD scale.

50% of the sample were men and the average age was 70. In comparing those with delirium alone and delirium plus dementia the average CTD score was much lower in the latter group but the large standard deviation meant that the populations overlapped for CTD scores. Similarly there was population overlap on the DRS-R98 severity scores where this time the latter group had an average score which was higher. I wasn’t convinced from these figures of a pragmatic utility in distinguishing between these diagnostic categories.

However, the authors drew up an interesting table in which they compared severity of scores with the individual items on the DRS-R98 scale. At any severity, sleep-wake cycle disturbance was present in 97% of the sample. A key finding was that disorientation was present at any level of severity in 76% of the sample and in only 42% of cases was it moderate-to-severe.  50% of people had perceptual disturbances including hallucinations at any level of severity. There was also a remarkable finding showing that the level of inattention on the CTD was significantly correlated with a number of items on the DRS-R98 with the implication that inattention is an explanation for many of the features of delirium.

The authors argue that in delirium therefore, the main feature is not disorientation but inattention and suggest this as a consideration for future diagnostic revisions. Another interesting finding was that motor symptoms (classically considered to be agitated versus hypoactive delirium) did not predict psychosis – in other words the quiet withdrawn people with delirium were just as likely to be experiencing psychosis.

This is a neat study with some very interesting findings in delirium.

STT3

Disclaimer

The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

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