Rates of thromboembolism associated with different indications for oral anticoagulation and risk reduction with anticoagulation.
| Indication . | Rate of Thromboembolism Without Anticoagulation . | Risk Reduction (%) . |
|---|---|---|
| Reproduced, with minor modifications, from Kearon and Hirsh1 | ||
| * An increase in the risk of venous thromboembolism associated with surgery (estimated to be 100-fold) is not included in these rates. | ||
| ‡ Last episode of venous thromboembolism more than 3 months previously, but require long-term anticoagulation because of high risk of recurrence. | ||
| † Risk reduction with oral anticoagulation; risk reduction with bridging therapy is uncertain but expected to be less (see discussion) | ||
| Abbreviations: NVAF, non-valvular atrial fibrillation | ||
| Venous Thromboembolism | ||
| Acute venous thromboembolism | ||
| 0–1 month | 40%/month* | 80 |
| 1–3 months | 10%/2 months* | 90 |
| Recurrent venous thromboembolism‡ | 15%/year* | 90 |
| Arterial Thromboembolism | ||
| NVAF | 4.5%/year | 75† |
| NVAF and previous embolism | 12%/year | 75† |
| Mechanical heart valve | 8%/year | 75† |
| Acute arterial embolism | ||
| 0–1 month | 15%/month | 75† |
| Indication . | Rate of Thromboembolism Without Anticoagulation . | Risk Reduction (%) . |
|---|---|---|
| Reproduced, with minor modifications, from Kearon and Hirsh1 | ||
| * An increase in the risk of venous thromboembolism associated with surgery (estimated to be 100-fold) is not included in these rates. | ||
| ‡ Last episode of venous thromboembolism more than 3 months previously, but require long-term anticoagulation because of high risk of recurrence. | ||
| † Risk reduction with oral anticoagulation; risk reduction with bridging therapy is uncertain but expected to be less (see discussion) | ||
| Abbreviations: NVAF, non-valvular atrial fibrillation | ||
| Venous Thromboembolism | ||
| Acute venous thromboembolism | ||
| 0–1 month | 40%/month* | 80 |
| 1–3 months | 10%/2 months* | 90 |
| Recurrent venous thromboembolism‡ | 15%/year* | 90 |
| Arterial Thromboembolism | ||
| NVAF | 4.5%/year | 75† |
| NVAF and previous embolism | 12%/year | 75† |
| Mechanical heart valve | 8%/year | 75† |
| Acute arterial embolism | ||
| 0–1 month | 15%/month | 75† |