Risk factors* | |||
| |||
Estimated absolute risk of major bleeding (%) | |||
Categorization of risk of bleedingΔ | Low risk◊ (0 risk factors) | Moderate risk◊ (1 risk factor) | High risk◊ (≥2 risk factors) |
Anticoagulation 0 to 3 months§ | |||
Baseline risk (%) | 0.6 | 1.2 | 4.8 |
Increased risk (%) | 1 | 2 | 8 |
Total risk (%) | 1.6§ | 3.2 | 12.8¥ |
Anticoagulation after first 3 months‡ | |||
Baseline risk (%/years) | 0.3† | 0.6 | ≥2.5 |
Increased risk (%/years) | 0.5 | 1 | ≥4 |
Total risk (%/years) | 0.8** | 1.6** | ≥6.5 |
GI: gastrointestinal; UFH: unfractionated heparin; LMWH: low molecular weight heparin; VKA: vitamin K-dependent antagonist (ie, warfarin); VTE: venous thromboembolism.
* The increase in bleeding associated with a risk factor will vary with (1) severity of the risk factor (eg, location and extent of metastatic disease, platelet count), (2) temporal relationships (eg, interval from surgery or a previous bleeding episode), and (3) how effectively a previous cause of bleeding was corrected (eg, upper-GI bleeding).
¶ Important for parenteral anticoagulation (eg, first 10 days), but less important for long-term or extended anticoagulation.
Δ Although there is evidence that risk of bleeding increases with the prevalence of risk factors, this categorization scheme has not been validated. Furthermore, a single risk factor, when severe, will result in a high risk of bleeding (eg, major surgery within the past 2 days, severe thrombocytopenia).
◊ Compared with low-risk patients, moderate-risk patients are assumed to have a 2-fold risk and high-risk patients an 8-fold risk of major bleeding.
§ The 1.6% corresponds to the average of major bleeding with initial UFH or LMWH therapy followed by VKA therapy. We estimated baseline risk by assuming a 2.6 relative risk of major bleeding with anticoagulation (refer to footnote ‡).
¥ Consistent with frequency of major bleeding observed by Hull et al in high-risk patients[1].
‡ We estimate that anticoagulation is associated with a 2.6-fold increase in major bleeding based on comparison of extended anticoagulation with no extended anticoagulation. The relative risk of major bleeding during the first 3 months of therapy may be greater than during extended VKA therapy because (1) the intensity of anticoagulation with initial parenteral therapy may be greater than with VKA therapy; (2) anticoagulant control will be less stable during the first 3 months; and (3) predispositions to anticoagulant-induced bleeding may be uncovered during the first 3 months of therapy. However, studies of patients with acute coronary syndromes do not suggest a ≥2.6 relative risk of major bleeding with parenteral anticoagulation (eg, UFH or LMWH) compared with control.
† Our estimated baseline risk of major bleeding for low-risk patients (and adjusted up for moderate- and high-risk groups as per footnote ◊).
** Consistent with frequency of major bleeding during prospective studies of extended anticoagulation for VTE.Reproduced from: Kearon C, Akl EA, Comerota AJ, et al. Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141:e419S. Table used with the permission of Elsevier Inc. All rights reserved.
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