2 Research recommendations

In 2010, the Guideline Development Group made the following recommendations for research, based on its review of evidence, to improve NICE guidance and patient care in the future.

2.1 Assessing the risk of VTE

What is the absolute risk of VTE among different groups of hospital patients, and can the risk be reliably estimated on admission to hospital to ensure that appropriate patients are offered VTE prophylaxis?

Why this is important

One of the most difficult areas the Guideline Development Group faced when developing the guideline was to identify the absolute risk of VTE among specific patient groups in relation to the reason for admission. A new, large pragmatic cohort study and/or record linkage study using Hospital Episode Statistics and the General Practice Research Database is proposed. This would allow all people admitted to hospital to be studied to identify those who develop VTE, including people who are diagnosed with VTE in primary care after discharge from hospital. Information on baseline patient‑related factors, procedures and duration of stay, complications, prophylactic therapies and concomitant drug use should be collected and analysed. It should allow the identification of independent risk factors for VTE and the development and subsequent validation of a risk model to estimate the absolute risk of VTE in individual patients. This research would allow clearer identification of those patients at risk of VTE and those in whom the risk is so low that the bleeding risk of pharmacological VTE prophylaxis would add overall hazard.

2.2 VTE prophylaxis for medical patients

What is the clinical and cost effectiveness of pharmacological prophylaxis, mechanical prophylaxis and combined pharmacological and mechanical prophylaxis for reducing the risk of VTE in medical patients?

Why this is important

Only a small number of trials with medical patients were identified and generally the inclusion criteria were narrow, for example, patients with an acute medical illness, with a hospital stay of more than 5 days, and often with severely limited mobility. Further research into less severely ill patient groups would be beneficial.

The evidence concerning mechanical VTE prophylaxis in medical patients is sparse. There have been a few small trials of patients with coronary syndrome but the only large, randomised controlled trial was of patients with stroke. This trial showed that routine care plus thigh‑length anti‑embolism stockings did not confer significantly more protection against VTE than routine care alone and was associated with significantly more harm. All of these trials included large proportions of patients who were taking aspirin, which may have influenced the results.

New trial(s) should investigate the benefits of reducing the risk of VTE balanced against the risk of bleeding. The trial(s) should compare pharmacological VTE prophylaxis alone, mechanical VTE prophylaxis alone, and combined mechanical and pharmacological VTE prophylaxis. The benefit of extended‑duration VTE prophylaxis in medical patient groups may also be investigated.

2.3 VTE prophylaxis for patients with lower limb plaster casts

What is the clinical and cost effectiveness of pharmacological prophylaxis for reducing the risk of VTE in patients with lower limb plaster casts?

Why this is important

A number of randomised controlled trials have been published reporting the use of VTE prophylaxis in patients with lower limb plaster casts. However, within these trials there has been a range of patients, including patients with soft tissue injuries and no operation, those with operated and unoperated fractures and patients having elective surgical procedures. The incidence of VTE in the published trials that did not use VTE prophylaxis ranges from 4–40%. The implications of providing pharmacological VTE prophylaxis for all patients with lower limb plaster casts are potentially considerable with respect to cost. Trials stratifying patients by reason for plaster cast would be useful to determine which patients should be recommended for VTE prophylaxis.

2.4 VTE prophylaxis for patients after stroke

What are the overall risks/benefits of LMWH and/or fondaparinux sodium in respect of both stroke outcome and the development of VTE for patients with acute stroke?

Why this is important

Patients with either ischaemic or haemorrhagic stroke have a risk of both VTE and bleeding into the brain. 'Stroke: diagnosis and management of acute stroke and transient attack [TIA]' (NICE clinical guideline 68, published July 2008) recommends the use of aspirin for treatment of ischaemic stroke but does not recommend anticoagulants. There is recent evidence to suggest that prophylactic doses of anticoagulants in addition to aspirin reduce the risk of VTE in patients with ischaemic stroke, but there are no data showing an effect of these anticoagulants on the stroke itself. Do they increase the risk of haemorrhagic transformation and so increase neurological damage? This research should include patients with haemorrhagic or ischaemic strokes to identify which patients would benefit from additional pharmacological VTE prophylaxis.

2.5 Incidence of post‑thrombotic syndrome after VTE

What is the incidence, loss of quality of life and cost associated with post‑thrombotic syndrome after potentially preventable deep vein thrombosis?

Why this is important

During development of the guideline it became apparent that the incidence of post‑thrombotic syndrome, particularly after asymptomatic deep vein thrombosis, was not well reported. This study should use standard, validated definitions to identify the incidence of post‑thrombotic syndrome both when a deep vein thrombosis has occurred as a result of a hospital admission and in the absence of hospital‑acquired deep vein thrombosis. The study should also aim to identify the costs to the NHS of treating post‑thrombotic syndrome.

  • National Institute for Health and Care Excellence (NICE)