So is the National Institute for Clinical Excellent (NICE) here to rescue is from the controversies. Well yes, and of course no…..so basically no.
The new guidance looks to incorporate the Wells score together with d-dimers and USS scanning of the lower limbs to diagnose DVT and there is much to like in their approach. It has an element of pragmatism about it, stating that there are different approaches depending on what is available – I like that – I’ve seen too many guidelines that stipulate processes only available 9-5 Mon-Fri (when the people who wrote them work) and not enough that are similarly useful at 2am on a Saturday night.
So, what’s new. Well the two level Wells score is fine. Previous scores using high, moderate and low scores as originally described seem to confuse lots of people (why?) and in reality the important group to define is the low risk (or DVT unlikely group). The Wells amendment from 2003 seems to make sense and has already been adopted by other centres in the UK.
What else? Well the big difference to me is the early use of proximal scanning for DVT. Fine and dandy as a rule in test if available but above knee DVT scanning misses lots of calf clots. This means that we might get an early diagnosis of a proximal DVT without pursuing d-dimers, waits for blood tests and general delay. I like this if it is available and indeed it is a skill that emergency physicians can own, and it’s unlikely to cause problems.
However, I think it’s fair to say that there is some controversy about what to do about clots below the knee and as the guidance states the evidence out there is not great with just a handful of low quality studies to help us answer the question (see page 50 of the guidance). However, my feeling is that if they are around then that’s useful to know. In the new NICE guideline scanning below the knee is not recommended in the algorithmn (though it is mentioned as an area for future research in the main text). If a patient is d-dimer positive but above knee DVT scan negative they go home and come back for another scan in 6-8 days to see if it has progressed.
Should we be worried about those 6-8 days without anticoagulation? Or is this a way of avoiding the potential risks associated with unnecessary anticoagulation? What would you do?
So what should we do in a centre such as ours with an excellent service that scans and diagnoses thrombolembolic disease throughout the lower limb venous system? My feeling is that we continue to investigate according to the best technology available. In my centre and several others this means that when we send a patient round for a scan we will be told whether or not they have a below knee DVT. I cannot then not know this information and I need to do something with it, it’s just really hard to ignore information once you have it and arguably very difficult to manage any future complaint or concern when there is an evidence trail back to you. So, I’d be really interested to know what others are doing with their below knee DVTs. Anticoagulate or not? If you do or you don’t who is driving that decision? You, your haematologists or your general physicians? My feeling having spoken to many EPs is that practice is really variable and that cannot be right for patients.
So, whilst the NICE guideline is good it is perhaps based on what is universally achievable rather than what is potentially excellent. Politically it is great when everyone is ‘equally excellent’ (whatever that means), but we all know that to not be the case. So for now I will aspire to be better than NICE and continue to take heed of clots in the calf…until some better evidence comes along at least (and I know a man who is doing just that as we speak @thegreathornero).