Professor Tom Treasure (left), Dr Lee-Yee Chong, and Dr Jennifer Hill outlinethe NICE guideline on the prevention of venous thromboembolism and the use of prophylaxis

Venous thromboembolism (VTE) is a condition in which a blood clot (thrombus) forms in a vein. It may dislodge from its original site and travel in the blood, a process known as embolism. It is estimated that every year there are 25,000 deaths in the UK from preventable hospital-acquired VTE.1 A UK survey performed at two hospitals and published in 2005 suggested that 71% of patients who were assessed to be at medium or high risk of developing deep vein thrombosis did not receive any form of VTE prophylaxis.2

In January 2010, NICE published Clinical Guideline 92, Venous thromboembolism: reducing the risk—reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in patients admitted to hospital,3,4 updating and replacing Clinical Guideline 46 on reducing the risk of VTE in inpatients undergoing surgery.5

Although most of the recommendations discussed in this article will be implemented when patients are admitted to hospitals, GPs should have good understanding of the VTE prophylaxis used. The duration of VTE prophylaxis recommended by the NICE guideline depends on the types of procedures and reasons of admission. Some patients will continue with VTE prophylaxis after they leave the hospital and the guideline recommends that their GPs should be notified.

Who is at risk?

Medical patients should be considered as being at risk if they have significantly reduced mobility (patients who are bedbound, unable to walk unaided, or likely to spend a substantial proportion of the day in a bed or in a chair) for 3 days or more.3 Patients who fall outside of this definition include mobile patients who have asthma, have taken an overdose, or are likely to go home in the next day or so.

Patients admitted for surgery, or because of injuries, should generally be considered as being at increased risk of VTE if they meet one of the following criteria:3

  • They will be undergoing an operation in which the anaesthetic and surgical time is more than 90 minutes, or 60 minutes if surgery is on the pelvis or a lower limb
  • They are an acute surgical admission with inflammatory or intra-abdominal condition with expected significant reduction in mobility
  • They have one or more of the risk factors listed in Table 1.
Table 1: Assessing the risks of venous thromboembolism and bleeding4
Patients who are at risk of VTE 

Medical patients

  • If mobility significantly reduced for ?3 days or
  • If expected to have ongoing reduced mobility relative to normal state plus any VTE risk factor

Surgical patients and patients with trauma

  • If total anaesthetic plus surgical time >90 minutes or
  • If surgery involves pelvis or lower limb and total anaesthetic plus surgical time >60 minutes or
  • If acute surgical admission with inflammatory or intra-abdominal condition or
  • If expected to have significant reduction in mobility or
  • If any VTE risk factor present

VTE risk factors*

  • Active cancer or cancer treatment
  • Age >60 years
  • Critical care admission
  • Dehydration
  • Known thrombophilias
  • Obesity (body mass index >30 kg/m2)
  • One or more significant medical co-morbidities (e.g. heart disease; metabolic, endocrine or respiratory pathologies; acute infectious diseases; inflammatory conditions)
  • Personal history or first-degree relative with a history of VTE
  • Use of hormone replacement therapy
  • Use of oestrogen-containing contraceptive therapy
  • Varicose veins with phlebitis
Patients who are at risk of bleeding

All patients who have any of the following:

  • Active bleeding
  • Acquired bleeding disorders (such as acute liver failure)
  • Concurrent use of anticoagulants known to increase the risk of bleeding (such as warfarin with international normalised ratio >2)
  • Lumbar puncture/epidural/spinal anaesthesia within the previous 4 hours or expected within the next 12 hours
  • Acute stroke
  • Thrombocytopenia (platelets <75 x 109/l)
  • Uncontrolled systolic hypertension (?230/120 mmHg)
  • Untreated inherited bleeding disorders (such as haemophilia or von Willebrand’s disease)

VTE=venous thromboembolism
*For women who are pregnant or have given birth within the previous 6 weeks, refer to page 23 of the NICE Quick Reference Guide
National Institute for Health and Care Excellence (NICE) (2010) CG92. Venous thromboembolism: Reducing the risk. Quick Reference Guide. London: NICE. Reproduced with permission. Available from www.nice.org.uk/guidance/CG92

 

Risk assessment

The first critical recommendation of the NICE guideline is that, on admission to hospital, all patients must be assessed for risk of VTE (see Figure 1).3 A risk assessment tool has recently been produced and is available on the internet for this purpose.6 All patients admitted to the hospital should be assessed for their level of mobility. All surgical and medical patients with significantly reduced mobility, should be considered for further risk assessment.

Any tick for thrombosis risk must trigger a plan to start VTE prophylaxis. Any tick for bleeding should prompt doctors to assess that risk and to consider if the bleeding risk is sufficient to avoid pharmacological prophylaxis.1 Patients assessed to be at increased VTE risk should be offered the appropriate VTE prophylaxis depending on the reasons for admissions (or procedures planned) and whether there are any risks for bleeding.1 Pharmacological prophylaxis should not be offered to patients with any risks factors for bleeding unless the risk of VTE outweighs the risk of bleeding; mechanical prophylaxis maybe a suitable option for these patients.3 The essential point is that prophylaxis is an opt-out rather than an opt-in process: the default should be to offer the patient protection against VTE unless a correctly completed chart shows that the patient is predicted to be at low risk of VTE.

Patients should be reassessed for risks of VTE and bleeding within 24 hours of admission and whenever the clinical situation changes to:3

  • ensure that the methods of pharmacological VTE prophylaxis are suitable and being used correctly
  • identify any adverse events resulting from prophylaxis.

It is also possible that a patient who had been considered as not at risk of VTE, on admission, has since deteriorated and is now considered at risk of VTE. Patients’ risks of VTE and bleeding may change during their course of hospitalisation and it is important to reassess to ensure the correct type of VTE prophylaxis is provided.

Figure 1: Care pathway for venous thromboembolism4
figure1
VTE=venous thromboembolism
National Institute for Health and Care Excellence (NICE) (2010) CG92. Venous thromboembolism: Reducing the risk. Quick Reference Guide. London: NICE. Reproduced with permission. Available from www.nice.org.uk/guidance/CG92

 

VTE risk versus bleeding risk

The Quick Reference Guide contains a variety of algorithms to assist the decision-making process of balancing the risks of VTE and bleeding before offering VTE for different patient types.4 The algorithms cover those who:

  • are general medical patients (see Figure 2)
  • have been admitted for stroke
  • have cancer
  • have central venous catheters
  • are in palliative care
  • are undergoing non-orthopaedic surgery
  • are undergoing orthopaedic surgery
  • have major trauma or spinal injury
  • have lower-limb plaster casts
  • are in critical care.

The type of pharmacological prophylaxis agents and mechanical methods recommended are dependent on the population type.

Figure 2: Care pathway for venous thromboembolism4
figure2

*At the time of publication (January 2010) some types of LMWH do not have UK marketing authorisation for VTE prophylaxis in medical patients. Prescribers should consult the summary of product characteristics for the individual LMWH. Informed consent for off-label use should be obtained and documented.

†For patients with renal failure.

VTE=venous thromboembolism; LMWH=low molecular weight heparin; UFH=unfractionated heparin

National Institute for Health and Care Excellence (NICE) (2010) CG92. Venous thromboembolism: Reducing the risk. Quick Reference Guide. London: NICE. Reproduced with permission. Available from www.nice.org.uk/guidance/CG92

 

Principles of care

Dehydration in patients should be avoided and individuals should be encouraged to return to full mobility as soon as possible. Aspirin and other antiplatelet agents should not be considered as adequate prophylaxis for VTE.3

The NICE guideline placed emphasis on clinicians using their clinical judgement when balancing risks and harms for each individual patient.

Methods of VTE prophylaxis

Mechanical
The choice of mechanical VTE prophylaxis should be based on clinical condition, surgical procedure, and patient preference. The NICE guideline recommends any one of:3

  • anti-embolism stockings (thigh or knee length)
  • foot impulse devices
  • intermittent pneumatic compression devices (thigh or knee length).

It is important to ensure that stockings are properly fitted (leg sizes may change due to oedema). Stockings should be removed on a daily basis for hygienic purposes and to monitor for adverse event such as blisters, marking, or discolouration of skin.3

Stockings and devices should not be offered to patients who have a known allergy to the material of manufacture. Anti-embolism stockings are not recommended for a number of patient types, including those admitted for stroke, cardiac failure, or suspected or proven arterial disease.3

Patients who have been offered mechanical VTE prophylaxis are encouraged to wear these devices for as much of the time as possible.

Pharmacological
Choice of pharmacological VTE prophylaxis should be based on local policies, individual patient characteristics, and preferences. Clinicians should refer to the specific algorithms to determine which agents should be chosen.4

The oral anticoagulants, dabigatran etexilate and rivaroxaban are possible VTE prophylactic choices for patients who have undergone elective hip or elective knee replacement surgery.3,7,8

Duration of prophylaxis
The duration of prophylaxis recommended is dependent on the patient population or surgical procedures (see
Table 2).

For medical patients, the general advice is to continue preventive treatment until the person is no longer at increased risk and so the decision reverts to clinical judgment.

For most surgical procedures, VTE prophylaxis should be continued until the patient no longer has significantly reduced mobility. For patients undergoing orthopaedic procedures or cancer surgery in the abdomen or pelvis, a longer duration of prophylaxis is recommended.

Table 2: Summary of type of prophylaxis and duration for various patient groups3
Patient group VTE prophylaxis Duration
General medical patients Pharmacological Until no longer at risk
Non orthopaedic surgery Mechanical
and/or*
pharmacological
Until mobile

Until mobile, generally 5–7 days
Cancer surgery in the abdomen or pelvis Mechanical
and/or*
pharmacological
Until mobile

For 28 days after surgery
Hip fracture or hip replacement Mechanical
and/or*
pharmacological
Until mobile

For 28–35 days after surgery
Knee replacement Mechanical
and/or*
pharmacological
Until mobile

For 10–14 days after surgery
Plaster cast Low molecular weight heparin Until plaster cast removed
VTE=venous thromboembolism
*Refer to the NICE guideline for full recommendations on when to add pharmacological prophylaxis to mechanical prophylaxis.

 

Patient discharge

The guideline emphasises the importance of providing patients with information about VTE and prophylaxis. As part of the discharge plan, all patients and/or their families or carers should be offered oral and written information about the signs and symptoms of deep vein thrombosis and pulmonary embolism, the importance of seeking medical help, and who to contact if deep vein thrombosis, pulmonary embolism, or other adverse events are suspected.

For patients discharged with VTE prophylaxis, healthcare professionals should ensure that they are able to use stockings or injections correctly, or have arrangements made for someone to be available who will be able to help them. They should also be provided with information about:

  • the correct and recommended duration of use of VTE prophylaxis at home
  • the importance of using VTE prophylaxis correctly and continuing treatment for the recommended duration
  • the signs and symptoms of adverse events related to VTE prophylaxis
  • the importance of seeking help and whom to contact if they have any problems using the prophylaxis.

The correct use of anti-embolism stockings can be a problem for some patients. Therefore, it is important to ensure that patients:

  • understand the benefits of wearing them
  • understand the need to remove them for personal hygiene
  • are able to replace them, or have someone available who will be able to do this for them
  • look out for adverse effects, such as skin marking, blistering or discolouration, particularly over the heels and bony prominences.

This information should be communicated to the general practice. The NICE guideline recommends that if a patient is discharged with VTE prophylaxis, the patient’s GP should be notified.3

Implementation

The NICE guideline is accompanied by a VTE prevention programme, produced by the Department of Health.9 This programme comes with a set of incentives and penalties, to ensure that the recommendations are applied to every patient coming into hospital, whether as an emergency admission, surgical, or medical, or for planned elective surgery.

Conclusion

The NICE guideline aims to ensure that, at the same time as managing the presenting complaint of a patient admitted to hospital, clinicians also assess the risk of VTE and provide effective and appropriate prophylaxis.

General practitioners will have a role of continuing the care after hospital discharge to ensure that patients will get the best possible chance of reducing their risk of VTE.

Acknowledgements

The authors would like to thank Carlos Sharpin, National Clinical Guideline Centre, for comments and input on drafts of this article.

NICE implementation tools

NICE has developed the following tools to support implementation of Clinical Guideline 92 on Venous thromboembolism: reducing the risk—reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in patients admitted to hospital. They are now available to download from the NICE website: www.nice.org.uk

Costing tools

National cost reports and local cost templates for the guideline have been produced:

  • costing reports are estimates of the national cost impact arising from implementation based on assumptions about current practice, and predictions of how it might change following implementation of the guideline.
  • costing reports are estimates of the national cost impact arising from implementation based on assumptions about current practice, and predictions of how it might change following implementation of the guideline.

Slide set

The slides are aimed at supporting organisations to raise awareness of the guideline and resulting implementation issues at a local level, and can be edited to cater for local audiences. This information does not supersede or replace the guidance itself.

Audit support

Audit support has been developed to support the implementation of the NICE guideline on venous thromboembolism. The aim is to help NHS organisations with a baseline assessment and to assist with the audit process, thereby helping to ensure that practice is in line with the NICE recommendations. The audit support is based on the key recommendations of the guidance and includes criteria and data collection tools.

Guide to resources

The guide to resources provides an overview of information directly related to the guidance either in terms of background, such as government policy documents, or practical help, such as pathways or toolkits.


Key Points
  • All patients admitted to hospital should be assessed for risk of VTE
  • Risk assessment should take into account both thrombotic risk and bleeding risk
  • Pharmacological VTE prophylaxis should not be offered to patients with any risk factors for bleeding unless the risk of VTE outweighs the risk of bleeding
  • Reassessment of risk of VTE and bleeding should take place within 24 hours of admission and whenever the clinical situation changes
  • Mechanical VTE prophylaxis includes:
    • anti-embolism stockings (thigh or knee length)
    • foot impulse devices
    • intermittent pneumatic compression devices (thigh or knee length)
  • Pharmacological VTE prophylaxis includes:*
    • low molecular weight heparin
    • unfractionated heparin (for patients with renal failure)
  • Patients should be given comprehensive information on the correct use and recommended duration of the VTE prophylactic method being used

*Other pharmacological options may be available for certain patient groups
VTE=venous thromboembolism

References

  1. House of Commons Health Committee. The prevention of venous thromboembolism in hospitalised patients. London: The Stationery Office, 2005.
  2. Rashid S, Thursz M, Razvi N et al. Venous thromboprophylaxis in UK medical inpatients. Journal of the Royal Society of Medicine 2005; 98 (11): 507–512.
  3. National Institute for Health and Care Excellence. Venous thromboembolism: reducing the risk—reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in patients admitted to hospital. Clinical Guideline 92. London: NICE, 2010. Available at: www.nice.org.uk/guidance/CG92
  4. National Institute for Health and Care Excellence. Venous thromboembolism: reducing the risk—reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in patients admitted to hospital. Quick Reference Guide. London: NICE, 2010. Available at: www.nice.org.uk/guidance/CG92
  5. National Institute for Health and Care Excellence. Venous thromboembolism: reducing the risk of venous thromboembolism (deep vein thrombosis and pulmonary embolism) in inpatients undergoing surgery. Clinical Guideline 46. London: NICE, 2007.
  6. Department of Health. Venous thromboembolism (VTE) risk assessment. London: DH, 2010. Available at: www.dh.gov.uk/en/Publicationsandstatistics/Publications/PublicationsPolicyAndGuidance/DH_088215
  7. National Institute for Health and Care Excellence. Dabigatran etexilate for the prevention of venous thromboembolism after hip or knee replacement in adults. Technology Appraisal 157. London: NICE, 2008. Available at: www.nice.org.uk/guidance/TA157/Guidance/pdf/English
  8. National Institute for Health and Care Excellence. Rivaroxaban for the prevention of venous thromboembolism after total hip or total knee replacement in adults. Technology Appraisal 170. London: NICE, 2009. Available at: www.nice.org.uk/guidance/TA170/Guidance/pdf/English
  9. Department of Health. VTE prevention programme. www.dh.gov.uk/en/Publichealth/Healthprotection/Bloodsafety/VenousThromboembolismVTE/DH_113359 (accessed 8 March 2010)G
  • Prevention of VTE is now a national priority and PBC consortia should seek to ensure the NICE guideline is followed by embedding it in its contracts with provider trusts
  • Compliance with the NICE recommendations could be incentivised by using the Commissioning for Quality and Innovation scheme with acute trusts (linking bonus payments to performance)
  • Specific standards for VTE prophylaxis post-discharge should be set and agreed with acute/community and primary care providers with clear responsibilities for monitoring and administration
  • A local care pathway could also cover possible GP involvement in the assessment of patients before surgery to reduce costs of pre-assessment clinics and cancelled operations
  • Agreement as to the drug therapy used and funding of this between secondary and primary care, especially for cancer and joint replacement surgery should be secured as a priority (normally the hospital is responsible for the first 28 days of prescription)

VTE=venous thromboembolism