VTE Risk Factors
Probability of symptomatic VTE from the time of hospital admission to 90 days post hospital discharge in patients admitted with acute medical illness.


This tool implements IMPROVE risk nomograms for clinically evident acute venous thromboembolism:

The IMPROVE VTE Risk Model: Provides an estimate of the probability of clinically evident acute venous thromboembolism from the time of hospital admission to discharge, based on risk factors that are known (or that can be reasonably estimated) at the time of hospital admission.

The cumulative VTE incidence from admission to 3-month follow-up was 1.0%, with 45% of VTE events occurring post-discharge.

Please note that these risk calculators are a beta version. A separate validation test of these models is under development.

Enter the individual clinical information using check box indicators. The results box will display the probabilities of acute VTE.


  1. Previous VTE is defined as: Evidence of previous episode(s) of acute venous thromboembolic episodes in patient history (prior to current admission).
  2. Thrombophilia is defined as: familial or acquired disorders of the hemostatic system that result in an increased risk of thrombosis. Examples include, antithrombin III deficiency, resistance to activated protein C, protein C and protein S deficiencies, prothrombin gene mutation, Factor V Leiden, antiphospholipid syndrome.
  3. Cancer is defined as: evidence of active malignancy (treated or untreated) within the past 6 months.

This tool is intended for educational purposes only.

For information about the IMPROVE database, please visit www.outcomes.org.


IMPROVE is an international observational database of outcomes for patients who are hospitalized for an acute medical illness. IMPROVE includes 52 hospitals in 12 countries that enrolled a total of 15,156 patients.

Visit www.outcomes.org for complete information.


Publications that document the approach employed to develop the IMPROVE Risk Models

  1. Tapson VF, Decousus H, Pini M, Chong BH, Froehlich JB, Monreal M, Spyropoulos AC, Merli GJ, Zotz RB, Bergmann JF, Pavanello R, Turpie AG, Nakamura M, Piovella F, Kakkar AK, Spencer FA, Fitzgerald G, Anderson FA Jr; IMPROVE Investigators. Venous thromboembolism prophylaxis in acutely ill hospitalized medical patients: findings from the international Medical Prevention Registry on Venous Thromboembolism. Chest, 2007 Sep;132(3):936-45
  2. Spyropoulos AC, Anderson FA Jr, Fitzgerald G, Decousus H, Pini M, Chong BH, Zotz RB, Bergmann JF, Tapson V, Froehlich JB, Monreal M, Merli GJ, Pavanello R, Turpie AG, Nakamura M, Piovella F, Kakkar AK, Spencer FA; IMPROVE Investigators. Predictive and associative models to identify hospitalized medical patients at risk for VTE. Chest. 2011 Sep;140(3):706-14. doi: 10.1378/chest.10-1944. Epub 2011 Mar 24. PMID:21436241
  3. Decousus H, Tapson VF, Bergmann JF, Chong BH, Froehlich JB, Kakkar AK, Merli GJ, Monreal M, Nakamura M, Pavanello R, Pini M, Piovella F, Spencer FA, Spyropoulos AC, Turpie AG, Zotz RB, Fitzgerald G, Anderson FA; IMPROVE Investigators. Factors at admission associated with bleeding risk in medical patients: findings from the IMPROVE investigators. Chest. 2011 Jan;139(1):69-79. doi: 10.1378/chest.09-3081. Epub 2010 May 7.
  4. Schulman S, Kearon C; Subcommittee on Control of Anticoagulation of the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis. Definition of major bleeding in clinical investigations of antihemostatic medicinal products in non-surgical patients. J Thromb Haemost. 2005;3:692–4.


The sole purpose of this web site www.outcomes.org is to provide educational information about the health conditions studied in our research registries. We assume no responsibility for how you use or interpret the IMPROVE VTE or Bleeding Risk Assessment Tools or any other information provided on this web site.