Delirium screening in the ED – The Canadian way-aye.

Wow it’s been a while.

I thought I’d posted the last journal club here – which was back in Mid September – we reviewed The Poker trial – I’ll get a review posted ASAP, but on with the task at hand.

This slight loss of memory ties in nicely with the paper we reviewed today at the Yorkshire EM HST day. Imagine it, critical appraisal in God’s own county. Engaged trainees. Talking about GEM. Beautiful.
(You can catch up with the goings on for trainees in our region here, have a look around if you’re thinking of coming to train here.)

On to the paper

Title of Paper: Prospective validation of the Ottawa 3DY scale by Geriatric Emergency Nurses to Identify Imparied cognition in Older Emergency Department Patients.

Published: Annals of Emergency Medicine 2016

The next patient is a bewildered looking 79 year old lady who had a fall whilst putting the bins out. Her daughter has arrived and tells you she’s concerned Mum isn’t her normal self today and seems confused. You perform a thorough top to toe examination and find no signs of significant illness or injury (bar a few scrapes on her arm). You now wonder best how to assess her cognition. You’re a diligent doc and so reach for the 30 point MMSE form, your nursing colleague gives you his best sympathy eyes with a cheery ‘see you in half an hour’. There must be something else you could use, some other sort of scoring tool. Surely?!

old-lady

Clinical Question: In older patients presenting to the ED, is the 3DY scale accurate at identifying those who have cognitive impairment?

Population: Patients aged > 75 presenting to ED
Intervention(s): Ottawa 3DY scale (Day, Date, Year, Spell WORLD backwards)
Comparison: Animal fluency Model
Outcome: Defintion of cognitive impairment based on an MMSE < 24. Gold standard: Applied to all patients. The 30 point Mini Mental State Exam (a score of 24 or more was used as the standard for diagnosis of cognitive impairment)
The Tests:

The 3DY scale consists of asking the patient the Day, Date, Year and spelling WORLD backwards (hence the 3DY) – a score of 3 and under is deemed abnormal.
The Animal Fluency Test: asking them to name as many animals as they can in 60 seconds, naming less than 15 is deemed abnormal.

Methods

The patients were prospectively recruited at one of 2 EDs in Canada, between 0800-1600 7 days a week.

In terms of generalisabilty this is difficult to apply to ALL of our patients. Canada’s cool and all that, but its not the UK, there’s got to be something different about Ottawans (I have no idea if that’s a word!) compared to Yorkshire folk.

There’s also the out of hours thing. I’m more confident there’s something different about them to those in that arrive during the day time (office hours), maybe their risk of CI is higher, wandering in the street, fallen on the way to the loo in the night, late night hallucinating, that sort of thing. Out of hours is why we LOVE EM isn’t it? Its so much more ‘fun’.

I also wonder whether 75 is a little old for screening for cognitive impairment in the ED – I tend to do it more frequently and very much dependent on the condition the patient presents with. I would have liked to see them take a more pragmatic standpoint on age and looked at those at 65 years old (which is actually what the WHO uses as the age of becoming ‘older’).

A sample size calculation was done based on the original derivation score data (a sensitivity of 80% and a bound on error of estimation of 10%), they ‘needed’ 256 patients based on the sample size calculation but only screened 254 and studied 238 after excluding some.
On the subject of numbers – 238 over 75s. In 8 months or so. In two hospitals. I appreciate they only used 0800-1600. But that’s still somewhere between 1-1.5 per day. I wonder if this represents ‘non consecutive’ patients. Or whether their exclusions were too ‘harsh’ to give a fair representative of ‘all comers’ in the ED.

I wondered about the selection of the Animal fluency model – I think this is a great sounding tool from the sense of patient and HCP enjoyment it could bring in a busy shift, but I’ve genuinely not heard of it being used routinely anywhere I’ve worked, maybe its because there isn’t an abundance of local wildlife in Yorkshire for the locals to have falling off the tips of their tongue.
I wish they’d used the AMT as a comparitor to the 3DY. (Purely selfishly as its the tool I use in my screening!)

lion-and-the-lamb_0

Results

32 of 238 patients had cognitive impairment – that’s around 14%.
3DY showed a Sensitivity of 93.8% (95% CI were 77.3-98.7%) and based on the 2×2 table you can calculate NPV at 98.6%. So a sensitivity of 93.8% and NPV of >98% that’s great right? Well, not really. Have a look at the confidence intervals on that sensitivity. It spans >20%. That’s a little bit too wide (imprecise) for me.

(Check out Andy Neil’s page here for some links to help revise all those critical appraisal definitions.)

The Animal fluency test scored slightly less well at predicting Cognitive impairment than the 3DY and also suffered with broad 95% confidence intervals.

The authors themselves highlight one further limitation of the paper, that the MMSE isn’t ‘the’ Gold standard for cognitive impairment, however I do think in the real world of acute care and admissions area it probably is. I’d probably go a step further and say that its rare for an MMSE to be conducted to 30 points in most of the EDs I’ve worked in most of the time.
How about 3DY plus a bit of collateral history from the patient’s nearest and dearest?

For me that’s where the meat lies. What does their regular caregiver say about them?
This sort of collateral history can be worth its weight in gold in an ED at 0200.

And I think that’s it for me with this paper – in terms of screening for cognitive impairment I don’t use the MMSE or the Animal Fluency Test, I use the AMT and bit of family collateral. I also practice at all hours of the day in the UK, and a lot of my patients who I’m concerned have altered cognition are much younger than 75!!!

This is a an interesting trial which is clearly appropriate for the patients they wanted to study, in the environment they’re working in. For me it poses more questions than it answers. But that’s cool too…..

Thanks for reading.

You can download the One Minute Wonder here 3dy

Keep fighting the good fight.

Chris

Refs: Prospective Validation of the Ottawa 3DY Scale by Geriatric Emergency Management Nurses to Identify Impaired Cognition in Older Emergency Department Patients. Wilding et al. Annals of Emergency Medicine. 2016.

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