The guideline
NICE. Venous thromboembolic diseases: the management of venous thromboembolic diseases and the role of thrombophilia testing. NICE 2012;CG144
Venous thromboembolisms range from asymptomatic deep venous thrombosis (DVT) to fatal pulmonary embolism (PE).
Non-fatal venous thromboembolic diseases may cause serious long-term conditions such as post-thrombotic syndrome or chronic thromboembolic pulmonary hypertension.
The mortality associated with venous thromboembolism (VTE) from any cause is not known in the UK. But preventable, hospital-acquired VTE alone causes 25,000 deaths a year in the UK.1
DVT can be a challenging clinical diagnosis in primary care – where we commonly see patients with leg pain, swelling and erythema usually due to cellulitis, trauma or peripheral oedema.
This article will summarise NICE's June recommendations on the management of confirmed or suspected venous thromboembolic diseases in adults.
Use the Wells score in suspected DVT
In a patient with signs or symptoms of DVT, conduct an assessment of their general medical history and a physical examination to exclude other causes.
If DVT is suspected, use the two-level DVT Wells score to estimate the clinical probability of DVT as ‘likely' or ‘unlikely' (see table below).
NICE recommends the Wells score as the most widely validated clinical decision rule, although some GPs may be more familiar with others, such as the Oudega rule.2 But the two-level Wells score is a useful tool (more so than the older three-level Wells score which separated patients into low, moderate and high risk).
Advice on when to use proximal leg scans
DVT ‘likely' on the Wells score
For patients who score ‘DVT likely':
- offer a proximal leg vein ultrasound within four hours and – if negative – a D-dimer test
- if a proximal leg vein ultrasound scan cannot be done within four hours, arrange a D-dimer test and an interim 24-hour dose of a parenteral anticoagulant, with a proximal leg vein ultrasound scan within 24 hours.
The proximal leg vein ultrasound scan should be repeated six to eight days later for anyone with a positive D-dimer test and a negative proximal leg vein ultrasound scan.
DVT ‘unlikely' on the Wells score
For patients who score ‘DVT unlikely', offer a D-dimer test. If the result is positive:
- offer a proximal leg vein ultrasound scan within four hours
- if a proximal leg vein ultrasound scan cannot be done within four hours, offer an interim 24-hour dose of a parenteral anticoagulant – usually low-molecular-weight heparin (LMWH) – with a proximal leg vein ultrasound scan within 24 hours
A greater role for D-dimer testing
The guideline implies a D-dimer test should be done as soon as a DVT is suspected – simple in hospital, but more challenging in primary care where we typically have a 24-hour turnaround for a serum sample. NICE suggests waiting this long would lead to an unacceptable risk of propagation of a clot, potentially leading to a PE. This presents a dilemma for GPs, most of whom won't be able to implement this guidance as it stands until CCGs reorganise services to make rapid D-dimer testing available.
Point-of-care D-dimer tests have been developed which give an accurate result within 10 to 15 minutes from a finger-prick blood sample, which makes them useful for primary care. Some GPs may already be using them in a DVT LES.
A 2010 study in the British Journal of General Practiceshowed that use of a clinical decision rule with point-of-care D-dimer testing reduced unnecessary referrals and missed very few DVTs. 1
Use the Wells score in suspected PE
In a patient with signs or symptoms of PE, a full assessment should be carried out, including: general medical history, a physical examination and a chest X-ray to exclude other causes. The two-level PE Wells score should then be used and a full assessment is crucial for an accurate result (see table below).
Again, this poses a dilemma for GPs who are unlikely to have access to rapid chest X-ray reporting. But, of course, if the PE Well's score means a PE is ‘likely', refer immediately.
Patients with a suspected PE and a Wells score above four (‘PE likely') should be referred for immediate CT pulmonary angiography. If this isn't possible, offer immediate interim parenteral anticoagulant treatment followed by CT pulmonary angiography. Consider a proximal leg vein ultrasound scan if the CT pulmonary angiography is negative and DVT is suspected.
For patients with ‘PE unlikely' on the Wells score, offer a D-dimer test. If positive, then follow the algorithm above for a Wells score over four. If negative, advise patients they are not likely to have a PE, discuss symptoms and signs of PE and when to seek medical review.
Update on use of LMWH or fondaparinux
Anticoagulation will almost always be initiated in secondary care. LMWH or fondaparinux is usually the preferred option, but unfractionated heparin is preferable in severe renal impairment or patients who have a high risk of bleeding or are haemodynamically unstable.
This initial anticoagulant is started as soon as possible and continued for five days or until the INR is normal (at least two) for at least 24 hours with warfarinisation, whichever is longer.
Continue anticoagulation for three months
Patients with a confirmed proximal DVT or PE should be started on an oral anticoagulant within 24 hours of diagnosis. At three months, assess the risks and benefits of continuing treatment.
Patients with an unprovoked PE or previous DVT should be offered oral anticoagulation beyond three months, taking into account the risk of recurrence and risk of bleeding. Patients with active cancer and confirmed proximal DVT or PE should be given LMWH for six months. At six months, assess the risks and benefits of continuing.
Advice on compression stockings
Offer below-knee, graduated compression stockings with an ankle pressure greater than 23mmHg (class II stockings) to patients with proximal DVT a week after diagnosis or when swelling is reduced sufficiently and there are no contraindications.
Advise patients to continue wearing them for at least two years – and ensure they are replaced two or three times a year or according to the manufacturer's instructions.
Make sure patients know they only need to be worn on the affected leg or legs.
Recommendations on cancer investigations
Any patient with an unprovoked DVT or unprovoked PE – not already known to have cancer – should be offered a physical examination (guided by the patient's history), chest X-ray, FBC, serum calcium, LFTs and urine analysis.
Consider an abdominopelvic CT scan (and mammography for women) in all patients aged over 40 years with a first unprovoked DVT or PE who do not have signs or symptoms of cancer, based on the above initial assessment.
When to do thrombophilia investigations
Don't offer thrombophilia testing to patients who are continuing anticoagulation treatment, or to those who have had ‘provoked' DVT or PE in the previous three months – for instance surgery, trauma, prolonged immobility, pregnancy or puerperium – or women on HRT or the
pill.
Consider testing for antiphospholipid antibodies in patients who have had unprovoked DVT or PE if stopping anticoagulation treatment is planned.
Consider testing for hereditary thrombophilia in patients who have had unprovoked DVT or PE and who have a first-degree relative who has had DVT or PE if stopping anticoagulation treatment is planned.
Do not routinely offer thrombophilia testing to first-degree relatives of people
with a history of DVT or PE and thrombophilia.
Dr Matt Hughes is a GP and hospital practitioner in cardiology in Cardiff
References
1 NICE. Venous thromboembolic disease. June 2012;CG144
2 Geersing G-J, Janssen K, Oudega R et al. Diagnostic classification in patients with suspected deep venous thrombosis: physicians' judgement or a decision rule? Br J Gen Pract 2010:60;742-8
