Reconsidering the burden of CRE screening

 

swabs

Shortly after the PHE Toolkit was published, I blogged some crude sums to size the burden of CRE admission screening a la Toolkit. I’m pleased to report that colleagues at Imperial have done a much better job of this, published in a letter in the Journal of Infection. The study provides some evidence that the recommendation in the PHE CRE Toolkit to perform pre-emptive isolation of suspected carriers whilst obtaining three negative screens is simply not feasible. The team then compare an alternate strategy – of applying the Tookit triggers to admissions to high risk specialties only (intensive care, nephrology, cardiothoracic surgery, neurosurgery and oncology).

To estimate the proportion of admissions who would meet the PHE trigger (modified to healthcare abroad or hospitalisation in a “high risk” hospital in the past 12 months), the team used data from a survey at the Royal Free. This survey found that around 20% of admissions were either hospitalised in a London hospital (17%) or received healthcare abroad (2%). This seems a little low: I suspect the figure for this in most hospitals will be closer to 50%. Even using the fairly conservative 20%, 3 million admissions would meet this trigger nationally. This would require a total of 6 million tests and a daily average of around 25,000 isolation days (adjusting for the fact that not all patients would stay for the 4 days required for 3 screens separated by 48 hours on days 0, 2 and 4). In contrast, the alternative strategy would identify <1 million admissions for screening, and generate <2 million tests and a daily average of <8000 isolation days.

Bear in mind that there are only just over 400,000 acute overnight beds in the NHS, so pre-emptive isolation for CRE would account for around 6% of all NHS beds. Since the proportion of single rooms is pretty low across the NHS (30% if you’re lucky), this represents a sizable proportion of isolation beds. And let’s not forget that single rooms are already full to bursting with patients with other infectious and non-infectious needs.

The authors didn’t add a price tag to their estimates, but if each isolation day costs £23, and each CRE test costs £5, then the bill for implementing the Toolkit would be £200m (yes, that’s 200,000,000) for isolation, and £30m for lab testing. If there was a finance director for the NHS, then they’d be less than pleased.

What we really need is some accurate data on CRE prevalence so that we can begin to make some evidence-based decisions about the most effective – and cost effective – admission screening strategies for CRE.

Image: ‘Swabs’ by Frank Carey.

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