What’s the point of point of care tests?

I remember, a good few years ago now, my GP trainer telling me that “GPST2 is about knocking the hospital out of you; not every patient needs a CRP.” She was, of course, absolutely correct. Now here I am, the expert generalist who can make decisions without investigations, going to ambulance call outs with an array of point of care tests (POCT) and working in the ED where the CRP is just an hour away. 

So how do I feel about POCT? Well, just because I have the equipment doesn’t mean I feel I have to use it. An analysis of day time GP urgent care POCT use in over 7,000 patients found a rate of use of just 1.3%. Our ambulance case mix is likely to be more complex and of higher acuity but having audited our scheme’s use, we only used POCT on 5% of those patients. 

There’s little point then? Well, the study above, a qualitative study of GPs using POCT on home visits and my own experience all agree that when used POCT makes a significant difference to the patient’s care. Many studies show that POCT of inflammatory markers can reduce antibiotic prescribing but I must confess I get more excited by situations where POCT can allow me to treat the patient safely at home. 

Situations such as the adult with learning disability and acute gastroenteritis with questionable urine output. They might well have had an acute kidney injury but a trip to hospital to check this would have been a massive upheaval. The POCT of their renal function took about six minutes and showed that it was safe to continue oral treatment at home. Then there was the palliative cancer patient who was vomiting – could it be hypercalcaemia? The POCT rapidly ticked that off and kept them comfortably at home. I’ve also identified surprisingly significant illness that changed the leave at home decision into an admission. I had an “off legs” patient with vague urinary symptoms but had also recently started a thiazide – the sodium of 115 would probably not have been fixed by a few days of nitrofurantoin!

So where do I see POCT going for me and in urgent care more generally? Well, I can see some of our current Urgent Care Course topics that POCT could relate to. The NHS Long Term Plan is keen that more care takes place in the community and we discuss new Hospital at Home schemes for frail patients – having rapid baseline bloods for these patients will no doubt make confidently referring these patients easier. We talk in more detail about fever in under 5s and how little there is clinically to spot or exclude severe illness; a 5-minute finger prick CRP may help a lot here and prevent unnecessary admissions and is something I will use more often in those borderline children. We discuss how easy ACS is to miss and this study from January suggests a POCT troponin performed on patients with a low clinical risk score can safely exclude ACS in quite a large number of people and therefore save time, money and reduce ED crowding.

Fundamentally, I don’t think POCT affects the main value of general practitioners in urgent care. Knowledge, experience, clinical and consultation skills really are the bread and butter. That said, I feel more confident in my ambulance visits having the blood tests to hand – emergency care is overcrowded and my patients only want to end up there if they really have to go. I think the real point of POCT is avoiding those trips to hospital to answer questions that can now be rapidly answered in the surgery or the out of hours centre or even the patient’s home. The real point of us is to identify when those questions actually need to be answered!