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VTE in Surgery

Major surgery is one of the well-recognized risk factors for VTE. Surgery within the last 45–90 days confers a 4- to 22-fold increase in the risk of VTE.1

Patients undergoing both elective and emergency surgery are recognized to be at very high risk of post-operative VTE.2 The prevalence of objectively-diagnosed DVT in surgical patients not receiving prophylaxis ranges from 10–80%, depending on type of surgery.

For patients undergoing general, vascular, gynaecologic, urologic, or laparoscopic surgery, DVT occurs in 15–30% of the cases.2 In orthopaedic surgery (hip or knee arthroplasty and hip-fracture surgery) the risk of DVT is 41–85% and of PE is 0.9–28%.2 Patients undergoing neurosurgery are known to be at moderately increased risk of postoperative VTE, which is approximately 22%.2 While in patients with severe trauma or spinal cord injury the rates are high as 40–80%.2

Data from a Spanish computerized registry of over 6,000 patients with VTE (RIETE) noted that 14% of subjects with some risk factors for VTE had undergone recent surgery. It was noted that 33% of at-risk surgical patients who went on to develop VTE had not received prophylaxis.3

The Global Orthopaedic Registry (GLORY) showed that cumulative incidence of VTE within 3 months of surgery was 1.7% in the total hip replacement (THR) and 2.3% in the total knee replacement (TKR) patients. The mean times to VTE were 21.5 ± 22.5 days for THR, and 9.7 ± 14.1 days for TKR. Of those who received recommended forms of prophylaxis, 26% of THR and 27% of TKR patients were not receiving it seven days after surgery, the minimum duration recommended at the time of the study.4

The fact that many cases of VTE do not emerge until after patients are discharged contributes to an under-appreciation of the problem. Physicians may be unaware or unfamiliar with the guidelines, or find them difficult to implement, given current resources. Some physicians may not perceive VTE as a significant problem, or consider VTE prophylaxis to be ineffective or associated with a risk of bleeding.5

There is an emerging literature hinting at reasons why surgical patients do not receive adequate prophylaxis despite their known risks for VTE. Although studies from the US suggest that 75% or more of high-risk surgical patients are given prophylaxis, in only 50% of cases is this prophylaxis appropriate in accord with current guidance on choice of antithrombotic agent, dose, and duration of therapy.6,7 In Spain, only 70% of orthopaedic and 58% of general surgical patients receive prophylaxis according to guidelines.8

There is a wealth of evidence-based medicine in support of the benefits and good safety profile of antithrombotic prophylaxis in patients undergoing surgery. The 7th ACCP guidelines recommend for use of LMWH or LDUH in moderate-to-high-risk general surgical patients (Grade 1A) and in vascular (Grade 1C+), gynaecological (Grade 1C+, Grade 1A), urologic (Grade 1C+, Grade 1A), and laparoscopic (Grade 1C+) surgery patients. Furthermore, LMWH, fondaparinux, or adjusted dose of VKA (Grade 1A) are recommended for prophylaxis in elective hip and knee arthroplasty.2 In patients undergoing neurosurgery, LDUH or postoperative LMWH are recommended as prophylaxis (Grade 2B, Grade 2A). For trauma (Grade 1A) and spinal cord injury (Grade 1B) patients, the guidelines recommend the use of LMWH as prophylaxis.

References

  1. Samama MM, Dahl OE, et al. Quantification of risk factors for venous thromboembolism: a preliminary study for the development of a risk assessment tool. Haematologica. 2003;88:1410-21.
  2. Geerts WH, Pineo GF, et al. Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy. Chest. 2004;126(3 Suppl):338-400S.
  3. Monreal M, et al. The outcome after treatment of venous thromboembolism is different in surgical and acutely ill medical patients. Findings from the RIETE registry. J Thromb Haemost. 2004;2:1892-8.
  4. Warwick D, Friedman RJ, et al. Insufficient duration of venous Thromboembolism prophylaxis after total hip or knee replacement when compared with the time course of thromboembolic events. J Bone Joint Surg. 2007;89-B:799-807.
  5. Kakkar AK, Davidson BL, et al. Compliance with recommended prophylaxis for venous thromboembolism: improving the use and rate of uptake of clinical practice guidelines. J Thromb Haemost. 2004;2:221-7.
  6. Stratton MA, Anderson FA, et al. Prevention of venous thromboembolism: adherence to the 1995 American College of Chest Physicians consensus guidelines for surgical patients. Arch Intern Med. 2000;160:334-40.
  7. Tapson VF, Hyers TM, et al. Antithrombotic therapy practices in US hospitals in an era of practice guidelines. Arch Intern Med. 2005;165:1458-64.
  8. Otero R, Uresandi F, et al. Use of venous thromboembolism prophylaxis for surgical patients: a multicentre analysis of practice in Spain. Eur J Surg. 2001;167:163-7.
 
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