Bleeding Risk Factors
Probability of Bleeding
Major0.0% Clinically Important0.0%


This tool implements IMPROVE risk nomograms for bleeding and clinically evident acute venous thromboembolism using two risk calculators:

The IMPROVE Bleeding Risk Model: Provides an estimate of the probability of major or clinically important in-hospital bleeding from the time of hospital admission up to 14 days following admission. Model risk factors were selected based on risk factors that were known (or that could be reasonably estimated) at the time of hospital admission.

The cumulative incidence of major and non-major but clinically relevant in-hospital bleeding within 14 days of admission was 3.2%.

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 the pop-up menus and check box indicators. The results boxes will display the probabilities of acute VTE and new clinically important bleeding.


  1. Major bleeding: Major bleeding was defined as: bleeding event contributing to death, clinically overt bleeding associated with a fall in hemoglobin level of ≥2 g/dL, or leading to transfusion of ≥2 units of packed red blood cells, or within a critical organ (including intracranial, retroperitoneal, intraocular, adrenal gland, spinal, or pericardial bleeding).
  2. Non-major but clinically relevant bleeding: was defined as overt gastrointestinal bleeding (except for insignificant hemorrhoidal bleeding), gross hematuria (macroscopic and lasting longer than 24 hours), substantial epistaxis that requires intervention and is recurrent and/or lasts ≥5 minutes, extensive hematoma or bruising (>5 cm in diameter), intra-articular bleeding (documented by aspiration), menorrhagia or metrorrhagia (increased quantity or duration), other bleeding important enough to be recorded on the hospital chart.
  3. Previous VTE is defined as: Evidence of previous episode(s) of acute venous thromboembolic episodes in patient history (prior to current admission).
  4. 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.
  5. Cancer is defined as: evidence of active malignancy (treated or untreated) within the past 6 months.
  6. Immobilization ≥7 days: Immobilized is defined as being confined to bed or bed and chair for 24 hours or longer. (e.g., unable to walk to the bathroom without help).
  7. Admission to an intensive/critical care unit: Patient is admitted to one of these units for at least 24 hours.
  8. Prior bleeding: History of clinically important bleeding during the 3 months prior to hospital admission
  9. Low platelet count: >50x109 at hospital admission
  10. Hepatic or renal failure: Severe renal failure is defined as chronic irreversible failure of both kidneys to function, as a result of which either regular renal dialysis or renal transplant is initiated, or a serum creatinine >3X ULN.
  11. Central venous catheter: Present at or during current admission.

This tool is intended for educational purposes only.

For information about the IMPROVE database, please visit


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 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 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.