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Preventing deaths from VTE in hospital 1: Risk factors.

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Part 1 of this two-part unit on venous thromboembolism (VTE) examines what VTE is, its risk factors in medical and surgical patients, its consequences and the financial costs to the NHS of both treatment and failure to prevent it.


VOL: 103, ISSUE: 37, PAGE NO: 26

Elizabeth Wilson, RGN, is a practising nurse and freelance writer

Part 1 of this two-part unit on venous thromboembolism (VTE) examines what VTE is, its risk factors in medical and surgical patients, its consequences and the financial costs to the NHS of both treatment and failure to prevent it.



Pulmonary embolism (PE) and deep vein thrombosis (DVT) - interrelated conditions known as venous thromboembolism (VTE) - kill more people each year than breast cancer, road traffic accidents, Aids and MRSA put together (House of Commons Health Committee, 2005).



As the number of postmortem examinations performed is declining, it is likely that the figure of over 25,000 deaths a year in England from VTE is conservative (HCHC, 2005). This equates to around three people every hour, making VTE the most common cause of hospital-related death (Geerts et al, 2004). The condition is preventable, yet we hear little about it in the media - although DVT associated with long-haul travel has often made the headlines.



A clot in a vein most commonly occurs in the deep veins of the leg or in the pelvis. Distal DVTs occur in the veins of the calf and are more common than proximal DVTs, which occur in the popliteal, superficial femoral, common femoral or iliac veins. They can also arise in the arms or deep veins elsewhere in the body but this is unusual (National Library for Health, 2007).



Signs and symptoms
Signs and symptoms of DVT in the leg vary. An acute onset of leg pain, which is often localised to one leg, swelling and difficulty in weight-bearing are all possible signs of DVT. There may be pitting oedema, tenderness on pressing the leg, distension of the superficial veins, a colour change in the leg and an increase in the skin temperature.



Diagnosis can be difficult and is made via a detailed history (risk factors, family history, recent surgery/hospital admission, concomitant disease, medication and recent activity/inactivity), examination and by ultrasonography +/- D-dimer blood test (National Library for Health, 2007).



This venous thrombus can be long and fill the veins and may break to form an embolus, which can travel through the venous system and heart and become lodged in the pulmonary system, causing a PE.



PE can also be difficult to diagnose - patients may have dyspnoea, pain or haemoptysis, or they may be asymptomatic (National Library for Health, 2007). The condition is serious and can be fatal, causing sudden death in about 20% of affected patients (Heit, 2002).



DVTs often go unrecognised as up to 80% are clinically silent (Lethen et al, 1997). Four out of five patients with a PE were also found to have a DVT (Geerts et al, 2004), so there may be no early warning of an embolic problem from this source.



There are many factors that can increase the risk of patients developing VTE; these are outlined in Box 1. They have various physiological causes that generally fall into the categories in Virchow’s triad. This was described 100 years ago and looks at the three features that can contribute to VTE - venous stasis, endothelial damage and a hypercoagulable state (National Library for Health, 2007). It is not unusual for more than one risk factor to affect each patient.



The risk of VTE varies between hospital specialties as it does between patients. The incidence of objectively documented DVT varies from 16-55% in medical and general surgical patients and from 50-60% in those who have undergone major orthopaedic surgery (Geerts et al, 2001).



The degree of risk is determined by risk assessment. Fig 1 gives an example of a medical risk assessment tool; an example of a surgical tool is shown on Portfolio Pages. The chief medical officer says the next phase of the work on VTE will be towards a national risk assessment tool (Department of Health and Donaldson, 2007).



In a US study, Heit et al (2001) found that the incidence of VTE in hospital patients was 100 times greater than it was in community residents. Therefore it would seem that simply bringing a patient into hospital is a risk factor in itself.



However, patients are still at risk after discharge from hospital. For example, in major orthopaedic surgery it has been found that the most frequent time of onset of PE was in the second and third weeks after surgery, with only around 10% occurring in the first week (Johnson et al, 1977). Patients with a hip fracture appear to be at a higher risk than those undergoing elective surgery (Edelsberg et al, 2001). This presents a strong case for extending prophylaxis for several weeks after discharge, especially as inpatient stays become shorter.



It is known that increased age carries an increased risk of developing VTE (Oger, 2000). Those over 40 years of age carry more risk than younger patients and it is thought the risk nearly doubles with each decade thereafter (Anderson et al, 1991), with those aged over 75 years being at greatest risk (Oger, 2000).



PE causes sudden death in some 20% of affected patients (Heit, 2002). For survivors of VTE, the long-term consequences can include recurrent DVT and/or PE, as having one event increases the risk of having another in the future. This happens in around 30% of patients eight years after the first episode (Prandoni et al, 1996). For patients who have had a DVT, post-thrombotic syndrome (PTS) may affect their continuing health.



PTS can occur years after the DVT and it is estimated that a third of patients will develop it within five years, irrespective of age. Signs and symptoms include pain, erythema, oedema, hyperpigmentation and skin ulceration (American Venous Forum, 2007), caused by interruptions to the blood supply in the vein and a backflow of blood because of the clot and any remaining obstructions. PTS causes long-term morbidity and its associated problems can continue for at least 20 years (National Library for Health, 2007), leading to poor quality of life for patients and increased costs for the necessary health services.



It is worth noting that these costs to health services are substantial. Over the past 10 years alone some £68m has either been paid or is still outstanding in clinical negligence claims (nearly 2% of all claims), from an already cash-strapped NHS (DH and Donaldson, 2007). In addition, the direct and indirect cost of treating and managing DVT and PE is around £630m - for the treatment of leg ulcers the cost is estimated at £400m (HCHC, 2005).



- Part 2 of this unit, which explores thromboprophylaxis and nurses’ roles in this, will be published in next week’s issue.



Learning objectives
1. Explain what VTE is and identify the risks that can lead to it.



2. Understand the consequences of VTE for patients and the NHS.



This article has been double-blind peer-reviewed

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