New NICE guidance on Investigation of DVT in the ED

Is Venous Thrombo Embolism the most controversial area of EM practice at the moment? I think it might be as there is rarely a meeting or conference where the subject is not discussed and debated.

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).

Simon Carley

11 responses to “New NICE guidance on Investigation of DVT in the ED

  1. I would like to not treat calf DVTs at all – i think they’re somewhat akin to the subsegmental PEs. I think they should be considered a different disease process as iliac vein DVTs or saddle emboli. I know there’s not much to support me on that but that’s how I see them.

    I like the idea of not treating the below knee DVTs and f/u scan and if still -ve then leave be. We’ve managed to do this in the main for superficial thromobophlebitis (at least I have) and i just wonder can we extend to to below knees.

    In practice a lot of the time i’ve discussed them with seniors and medics and they always say treat. If I had a below knee I’d want follow up not warfarin.

    • Would you Andy? It’s a tricky one I think as it depends a little on what you are worried about in terms of outcome. The data is just not there I know, but I am worried not just about PE and death, but also post thrombotic limb syndrome and I just don’t know what anticoag will do.

      As a fellow young (you younger than me), fit and healthy individual the risk to you and me from anticoagulation is low. We are not 75 year old arteriopaths so we should be fine on warfarin for a while, though I agree the risk is not zero.

      I think I would go for anticoagulation, and I’d ask for one of the newer oral anticoagulants thank you very much.

      Lastly, I’d want my doc to really look for reason why I have a DVT. I shouldn’t have one so what’s going on? This is a whole new area that we need to think about. Is DVT a diagnosis in itself, or just a clinical sign for something else?

      S

  2. I wrote a similar set of guidelines for my ED about 3 years ago (glad to see NICE has caught up! ;-))
    There is no good evidence for how to treat below knee DVT. This was a SCE (viva) question in the FACEM exam a couple of years back too, which I think emphasised this point.
    My inital emergency physician inclination was to dismiss them as ‘not life-threatening’ and not a big deal.
    But the vascular surgeons I spoke to were for aggressive anticoagulation – e.g. for 6+ weeks with serial ultrasounds – I think because they see the cohort of patients that develop bad problems with post-phlebitic syndrome.
    However where’s the evidence that that works?
    In my practice I try to weigh up all the intangibles and have a patient-centered discussion about the pros and cons of DVT stockings only vs apsirin vs anticoagulation and the need for a follow up ultrasound.
    Don’t believe anyone who says they know the answer!
    Chris

  3. Hi Chris,

    Top comment and to be honest I was pretty shocked to see the paucity of evidence as I have come across LOTS of people who were absolutely certain that we should/should not treat below knee DVTs. I guess since you know your Osler you will agree that the greater the ignorance the greater the Dogma….. Our local practice I must admit has been to treat below knee DVTs but I agree this is FBM (faith based medicine) rather than EBM (evidence based medicine).

    S
    PS – sorry for the delay. WordPress put you and Mike in the spam folder! I have de-spammed you 😉

  4. Mike I can understand…
    Me – guilt by association?
    Really looking forward to see our http://stemlynsblog.org develops – I think this is going to be HUGE – welcome to the party!
    Chris

  5. Really interesting to hear your comments on this as it is a special interest of mine. Hoping that our upcoming data will give some perspective on what happens to the untreated, in addition to the other ongoing studies. There is an IDDVT (isolated distal DVT) party at the moment and evidence is on the verge of the horizon:

    http://www.ncbi.nlm.nih.gov/pubmed/22472294
    http://www.southernhealth.org.au/content/Document/Education/DistalDVTprotocol%20(Vers%204%2018.01.11).pdf
    http://clinicaltrials.gov/ct2/show/NCT00421538

    Andy – I am sure you have seen but serial follow up with ultrasonography is the recommended first line in the new Chest 2012 guidelines http://journal.publications.chestnet.org/article.aspx?articleid=1159410
    British guidelines still say treat. Most European surveys suggest 80-90% get treated.

    Watch this space……..

    Dan H (not Simon)

  6. Untreated superficial thrombophlebitis may lead to PE although infrequently. Fondaparinux 2.5 mg apparently prevents extension to the deep veins (Calisto study). I was wondering whether it could be an alternative to full anticoagulation therapy even for calf DVTs. I came across patients with massive PEs in whom only calf DVTs or superficial thrombophlebitis could be detected. In my mind they were leftovers of an unidentified (maybe peripherally growing) extended thrombotic process. I pay lots of respect to calf DVTs since I don’t think we can really predict which are going to extend proximally. So beside a close followup I’d like to have patients on an anticoagulation regimen that would just prevent them to extend. Maybe in medio stat virtus.

  7. Hi Squartadoc.

    I have a similar respect for these symptomatic calf DVTs and nasty looking SVTs. The work we are finishing up in Manchester at the moment suggests 1 in 10 untreated calf DVT patients will propagate above the knee or develop a PE. That fits with previous data. It is certainly the case that there is a potential to develop PE within the first week when using serial ultrasound follow up.

    If you decide they need treating, then the question of what to use is a really thorny one. Rhigini et al did a nice literature review previously summarising the different methods of treatment utilised over the last 20 years (Righini M, Paris S, Le Gal G, Laroche JP, Perrier A, Bounameaux H. Clinical relevance of distal deep vein thrombosis. Review of literature data. Thromb Haemost. 2006 Jan;95(1):56-­64).

    There is an argument for a prophylactic regimen of anticoagulation. There is also an argument for a reduced 6 week course of treatment http://www.ncbi.nlm.nih.gov/pubmed/11369685. Studies looking at reducing courses for 4 weeks or less have been disappointing however http://www.ncbi.nlm.nih.gov/pubmed/19190559.

    There are no studies looking at Fondaparinux for IDDVT. But you could well be right, it may have similarly efficacious results to the CALISTO trial with limited adverse events. Nothing to support this as yet though.

    My main interest in taking this forward is with the NOACs (New Oral AntiCoagulants). I think a short course of Rivaroxaban for calf DVT may well reduce symptoms and serious potential complications. It will probably be cost effective also if you think about saving people 10 follow up clinic visits and no further ultrasound scans. When you factor in the time off work, transport costs and the costs of medical review I think this may be the way forward.

    It just needs the evidence to support it. Anyone fancy getting involved in a multi centre trial? I am fleshing out the funding bid as we speak….

    Dan H.

  8. I definitely see the point you make and is convincing to me. So basically rivaroxaban for 45-60 days no doppler control until the end. Outcomes? Death any cause, TEP, dvt extension, bleeds?
    How many pt roughly if I may know?

  9. I find it hard to disregard below knee DVTs, although it is obviously the practice in some settings. In my particular ED, we have a hematologist who runs a Haemostasis and Thrombosis service. His advice is to anticoagulate in the first instance pending serial ultrasound and review. Without a clear provocation and particularly in the younger patient, a thrombophilia screen is performed.

    I would be interested what the evidence points to. I have worked in EDs where BKDVTs were just rescanned. Our particular service in my current ED also anticoagulates superficial venous thromboses in the first instance.

    Intuitively the idea of a short course NOAC sits comfortably with me.

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