IMPROVE VTE Risk Score
Predicts 3-month risk of symptomatic VTE in acutely ill hospitalised medical patients
For use by health professionals only. This tool does not replace clinical judgement, local VTE prophylaxis guidelines, or a separate bleeding-risk assessment. Not for patient self-management.
Risk factors (IMPROVE VTE RAM)
IMPROVE VTE score: 0 / 11
Risk category: Not yet calculated
Approximate 3-month VTE risk: —
Select the relevant risk factors and click “Calculate score” to see the IMPROVE VTE score and its interpretation.
Interpretation (for acutely ill medical inpatients):
0–1 = low risk (<1% 3-month symptomatic VTE); 2–3 = moderate risk (~1–2%);
≥4 = high risk (~5–6%). Pharmacologic VTE prophylaxis and/or extended prophylaxis
should be guided by local protocols, bleeding risk, and clinical judgement.
The IMPROVE VTE Risk Score is a clinical risk assessment model used in acutely ill, hospitalised medical patients to estimate their 3-month risk of symptomatic venous thromboembolism (VTE) (deep vein thrombosis or pulmonary embolism). It comes from the International Medical Prevention Registry on Venous Thromboembolism (IMPROVE), which followed over 15,000 medical inpatients for 3 months after admission.PubMed
By identifying key clinical risk factors and assigning weighted points, the score helps stratify patients into low, moderate, or high VTE risk. This stratification can then be combined with a bleeding-risk assessment to decide whether to start pharmacologic thromboprophylaxis (e.g. low-molecular-weight heparin) and whether extended prophylaxis after discharge is appropriate.PubMed+1
Components of the IMPROVE VTE Risk Score
The standard IMPROVE VTE risk assessment model (RAM) uses 7 clinical risk factors present at admission and/or during hospitalisation:ScienceDirect+1
- Previous VTE – 3 points
- Known thrombophilia – 2 points
- Current lower-limb paralysis – 2 points
- Current cancer – 2 points
- Immobilisation ≥7 days – 1 point
- ICU/CCU stay – 1 point
- Age >60 years – 1 point
Total score range: 0–11 points.
These factors were identified as independent predictors of symptomatic VTE within 3 months of admission in the original derivation cohort.PubMed+1
Interpretation and clinical use
Commonly used categories for the IMPROVE VTE score are:ScienceDirect+2SpringerLink+2
- 0–1 points: Low risk
- Observed 3-month symptomatic VTE risk is <1% in validation cohorts.
- 2–3 points: Moderate risk
- Approximate 3-month VTE risk ~1–2%.
- ≥4 points: High risk
- Approximate 3-month VTE risk ~5–6%.
Many guidelines and decision analyses use thresholds such as IMPROVE ≥2 or ≥4, combined with a low bleeding risk, to identify patients who are most likely to benefit from pharmacologic VTE prophylaxis or extended post-discharge prophylaxis.ScienceDirect+2PMC+2
There are also variants of the score:
- IMPROVE Predictive Score – a 4-factor on-admission version (previous VTE, cancer, thrombophilia, age >60).practical-haemostasis.com+1
- IMPROVE-DD (IMPROVEDD) – adds D-dimer ≥2× upper limit of normal as 2 additional points, improving discrimination between moderate- and high-risk patients and helping select candidates for extended prophylaxis.PMC+1
