Bayer Pharma AG

Essence of this Article

Therapies to prevent venous thromboembolism (VTE) vary in efficacy and risk of adverse events, so the decision to provide anticoagulant prophylaxis must take these factors into consideration. Generally, the benefits of thromboprophylaxis after major orthopaedic surgery have been shown to outweigh the risks of bleeding, regardless of the therapy used. Immobilized medical patients are also at risk of VTE, and although thromboprophylaxis is effective, it has not been shown to reduce mortality in this population. Extended thromboprophylaxis has been associated with an increased risk of bleeding. Simple scores that assess the risk of bleeding, such as that developed using the IMPROVE registry, can help physicians identify patients suitable for anticoagulant prophylaxis.

Balancing the benefits and risks of anticoagulant therapy for venous thromboembolism prevention

Therapies employed to prevent VTE vary in their efficacy and risk of adverse events, such as bleeding. Thus, the decision to provide anticoagulant prophylaxis must take into consideration these factors.

Generally, the benefits of thromboprophylaxis after major orthopaedic surgery have been shown to outweigh the risks of bleeding, regardless of the therapy used.54 Data regarding thromboprophylaxis after hip fracture surgery are more limited, but low molecular weight heparin (LMWH), low-dose unfractionated heparin, warfarin and fondaparinux appear to have positive efficacy and safety profiles.54

Immobilized medical patients are also at risk of VTE, and thromboprophylaxis is effective,54 although it has not been shown to reduce mortality in this population.110 Extended thromboprophylaxis has been associated with an increased risk of bleeding.66-68

Patient characteristics that are associated with an increased risk of bleeding with anticoagulant use include:111

  • Advanced age (>65 years)
  • Cancer
  • Renal failure
  • Liver failure
  • Comorbidity and reduced functional capacity

Heparin-induced thrombocytopenia (HIT) is an adverse event that can be associated with the use of heparins in up to 5% of patients after cardiac or orthopaedic surgery:112

  • HIT usually occurs in the first weeks of therapy; therefore, platelet counts should be monitored in patients receiving heparins for more than a few days

Validated risk scores for bleeding

Simple scores that assess the risk of bleeding can help physicians to decide whether a patient should receive anticoagulant prophylaxis. Such a score was developed using the IMPROVE (International Medical Prevention Registry on Venous Thromboembolism) registry, which provides data to help assess the risk of bleeding in hospitalized medical patients. Results from this observational study of over 10,000 patients who were not bleeding at the time of admission revealed the following risk factors:111

Validated risk factors for bleeding111

Bleeding risk factors Points
Active gastroduodenal ulcer 4.5
Bleeding during the 3 months before admission 4
Platelet count <50 × 109 cells/l 4
Advanced age (≥85 years vs <40 years) 3.5
Severe renal failure, eGFR <30 ml/min/m2 vs ≥ 60 ml/min/m2 2.5
Hepatic failure (INR >1.5) 2.5
Intensive care unit/coronary care unit 2.5
Central venous catheter 2.5
Rheumatic disease 2
Cancer at the time of hospital admission 2
Age, 40–84 years vs <40 years 2
Male sex 1.5
Moderate renal impairment, GFR 30–59 ml/min/m2 vs ≥60 ml/min/m2 1
eGFR, estimated glomerular filtration rate; INR, international normalized ratio.

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Risk of bleeding was shown to increase exponentially in patients with a risk score of ≥7.0 points. In the cases where bleeding contributed to death, the mean score was 8.6. Both major bleeding and any bleeding were uncommon in patients with a bleeding risk score of <7.0.111


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