For healthcare professionals
IMPROVE VTE risk score calculator
The IMPROVE VTE risk score estimates the risk of venous thromboembolism (a blood clot in a vein, such as a deep vein thrombosis or pulmonary embolism) in adults admitted to hospital with an acute medical illness, from seven items scored 1 to 3 points. This tool is written for clinicians. It is not a self-check and not a diagnosis.
Patient findings
For an adult admitted to a medical (non-surgical) ward. Nothing you enter leaves this page.
What you will see
The total IMPROVE VTE score from 0 to 12, the points for each item, the risk group and the published 3-month VTE risk for that score.
Educational only, not medical advice. A score never replaces the judgment of the treating team.
Source
The IMPROVE associative model by Spyropoulos and colleagues, Chest 2011, with the items, points, risk groups and 3-month VTE risk as printed in Table 2 of the open access review by Alfehaid and colleagues, Frontiers in Cardiovascular Medicine 2025 (CC BY). The tests check each item, the age edge, the range of 0 to 12, the group for the edge scores and the printed risk for every score.
Validated in
Acutely ill adults admitted to medical wards in the International Medical Prevention Registry on VTE (IMPROVE), which enrolled 15,156 patients in 52 hospitals in 12 countries from 2002 to 2006. We cite the 2011 paper but do not quote it, because its license does not allow reuse here. The score was validated externally by Rosenberg and colleagues in 2014.
Limits
For medical inpatients, not for surgical patients (see the Caprini score) or outpatients with cancer (see the Khorana score). The risks are group figures from the registry, not a prediction for one patient, and the registry did not assign prophylaxis at random. The review prints the low group as '0 to 1.5'; with whole-number points this is the same as 0 to 1. The table also prints the top row of its other risk column as 'Score >5 = 7.2%'; this tool follows the 3-month column, which prints 5 or more. An age of 60 does not count; 61 does.
The point table
IMPROVE VTE risk score (the 7-item associative model), as printed in Alfehaid and colleagues 2025 (Alfehaid 2025) (Spyropoulos 2011):
- Previous VTE: 3
- Current malignancy (cancer): 2
- Thrombophilia: 2
- Paralysis of the lower extremities during hospitalization: 2
- Immobilization for at least 7 days: 1
- ICU or CCU admission: 1
- Age over 60 years: 1
The total ranges from 0 to 12 (Alfehaid 2025). Worked example: a 72-year-old (1) admitted with pneumonia, with active lung cancer (2), who needs a stay in intensive care (1) and has no previous clot, no known thrombophilia, no paralysis and has not been immobilized for 7 days, scores 4, the high risk group.
The same review prints a 4-item version for use on admission (the IMPROVE predictive score) and a version that adds 2 points for a D-dimer over twice the upper limit of normal (IMPROVEDD) (Alfehaid 2025). This calculator uses the 7-item score.
Risk groups and 3-month VTE risk
Groups and risk as printed in the review (Alfehaid 2025):
- Low risk, score 0 to 1
- Moderate risk, score 2 to 3
- High risk, score 4 or more
| Score | 3-month VTE risk |
|---|---|
| 0 | 0.4% |
| 1 | 0.6% |
| 2 | 1.0% |
| 3 | 1.7% |
| 4 | 2.9% |
| 5 or more | 7.2% |
Source: Table 2 of Alfehaid and colleagues 2025 (Alfehaid 2025), from the original IMPROVE analysis (Spyropoulos 2011).
Reading the result
The score was validated externally by Rosenberg and colleagues (Rosenberg 2014). The review reports an area under the curve of 0.66 (95% CI 0.56 to 0.75) for the 7-item score in an external validation by Cobben and colleagues, and notes that the score does not include biomarkers such as D-dimer (Alfehaid 2025). The score supports a decision about clot prevention, weighed against bleeding risk; it does not make that decision on its own.
Related tools
The Padua prediction score is another VTE risk model for medical inpatients, and the Caprini score is the matching model for surgical patients. For outpatients with cancer starting chemotherapy, see the Khorana score. When a clot is already suspected, see the Wells score for DVT and the Wells score for PE. Other bedside scores are listed under For healthcare professionals.
Sources
- Alfehaid L, Alsuhebany N, Tawfik YMK, et al. A comprehensive review of venous thromboembolism risk assessment models for hospitalized medical patients: comparative evidence, implementation challenges, and future directions. Front Cardiovasc Med. 2025;12:1738139. doi:10.3389/fcvm.2025.1738139. PMID 41602342. Open access (CC BY). Table 2. pmc.ncbi.nlm.nih.gov/articles/PMC12833051/
- Spyropoulos AC, Anderson FA Jr, FitzGerald G, et al. Predictive and associative models to identify hospitalized medical patients at risk for VTE. Chest. 2011;140(3):706-714. doi:10.1378/chest.10-1944. PMID 21436241. doi.org/10.1378/chest.10-1944
- Rosenberg D, Eichorn A, Alarcon M, McCullagh L, McGinn T, Spyropoulos AC. External validation of the risk assessment model of the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE) for medical patients in a tertiary health system. J Am Heart Assoc. 2014;3(6):e001152. doi:10.1161/JAHA.114.001152. PMID 25404191. pmc.ncbi.nlm.nih.gov/articles/PMC4338701/
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-11-03. Spotted an error? See About.