DVT in hospitals: guideline implementation
While much media coverage of DVT has focussed on long-distance travel, it is perhaps less publicly-known that many patients develop DVTs whilst in hospital and that DVT is the most common form of preventable death in hospital. A number of clinical guidelines have been developed to tackle this problem, but how extensively are they being implemented? Dr Kerstin Hogg, Dr Steve Jones and Professor Kevin Mackway-Jones review the evidence.
- 60% of diagnoses of DVT occur during hospital admissions for unrelated conditions.
- 10% of hospital deaths are due to venous thromboembolic disease (VTE).
- Medical as well as surgical patients are at risk.
- Several evidence-based guidelines exist for prevention of VTE.
- Compliance to these guidelines is variable.
- The key challenge is the implementation of the guidelines.
Declaration of interests: No conflict of interests declared
Deep vein thrombosis and pulmonary embolism co-exist as part of the thromboembolic disease process. In 1976, the mortality of recognised and treated pulmonary embolism was 8%.1 Despite increased awareness of this disease and changes in prevention, diagnosis and treatment there has been little improvement in the prognosis with recent registries reporting the mortality to be 7%.2
Sixty per cent of all patients diagnosed with DVT develop the condition during hospital admission for an unrelated illness and 10% of hospital deaths are caused by VTE.3 Whilst certain surgical procedures, such as major joint replacement, colorectal surgery and surgery for cancer, have long been associated with a high risk of VTE, recent studies have demonstrated that older medical patients hospitalised with acute illness have a comparable risk. In 2004 the American College of Chest Physicians (ACCP) stated that ‘PE is the most common preventable cause of hospital death and is the number one strategy to improve patient safety in hospitals’.4 Those patients who develop PE during hospital admission are not only at risk of death but also a prolonged hospital stay and anticoagulant therapy. Patients who develop DVT are at risk of PE (either in hospital or at home following discharge) as well as post-thrombotic syndrome of the affected leg.
There are several evidence-based guidelines for the prevention of VTE. These have been produced by specialty organisations such as Investigators Against Thromboembolism (INATE), and the ACCP as well as national organisations, for example the Scottish Intercollegiate Guideline Network (http://www.sign.ac.uk). Despite the publication of these guidelines, the use of VTE prophylaxis varies markedly.
This short review attempts to collate evidence for the inpatient risk of VTE, optimal prevention strategies and their implementation. The referenced studies used a variety of techniques to verify primary endpoints of DVT and PE. The authors acknowledge this and accept the heterogeneous nature of the summated endpoints. Many studies (in particular surgical inpatient studies) assess the incidence of both symptomatic and asymptomatic DVTs. The clinical relevance of an asymptomatic DVT remains unclear, however evidence suggests that interventions reducing the incidence of asymptomatic DVTs produce a similar reduction in PE.5,6
Patients undergoing surgical procedures
Patients undergoing operations for joint replacement and hip fracture are at high risk of VTE. About 50% of patients undergoing hip fracture surgery without prophylaxis develop VTE.4,7 Twenty percent of deaths following orthopaedic surgery are caused by PE.8 When treated with prophylactic low molecular weight heparin (LMWH), the rate of DVT following knee replacement surgery is 33%, and hip replacement is 14%.4 These patients are at risk because they tend to be elderly, the operative procedure obstructs lower limb venous return, and postoperative mobility can be poor.
There are a few small studies suggesting that mechanical methods such as pneumatic compression boots reduce the incidence of post-operative DVT.7 One multicentre study has demonstrated that aspirin can reduce VTE following hip fracture surgery by 36% and knee or hip replacement surgery by 18%.9 Following major orthopaedic surgery the use of warfarin, low dose unfractionated heparin or LMWH reduces the incidence of VTE to around