IMPROVEDD Risk Score for VTE
Predicts risk of VTE in hospitalized patients, adding D-dimer to IMPROVE Risk Score.
Creator
Dr. C. Michael Gibson, MS, MDInstructions
Can be used to assess the risk of VTE in hospitalized patients to guide thromboprophylaxis decisions.
Published external validation studies are in hospitalized COVID-19 populations, which may not be generalizable to the broader medical inpatient population for which the score was designed.
IMPROVEDD VTE Risk Score
The IMPROVEDD score is an enhanced version of the IMPROVE VTE Risk Score that incorporates D-dimer, a blood biomarker of fibrin breakdown, to improve identification of hospitalized medical patients at risk for venous thromboembolism. It was built specifically to answer whether adding a readily available lab value could sharpen the discrimination of the original 7-item clinical IMPROVE VTE score.
Development
The score was derived by Gibson, Spyropoulos, Cohen, and colleagues (TH Open, 2017), using data from 7,441 hospitalized, medically ill patients enrolled in the APEX trial. Using Cox regression analysis, the researchers found that baseline D-dimer ≥2× the upper limit of normal (ULN) was independently associated with symptomatic VTE through 77 days of follow-up (adjusted HR 2.22). Based on the magnitude of this association relative to each point in the existing IMPROVE score, D-dimer was assigned a weight of 2 additional points when elevated.
Scoring
Addition of the selected points:
Variable | Points | |
Previous VTE | Yes | 3 |
No | 0 | |
Known thrombophilia | Yes | 2 |
No | 0 | |
Current lower-limb paralysis | Yes | 2 |
No | 0 | |
Current cancer | Yes | 2 |
No | 0 | |
Immobilized ≥7 days* | Yes | 1 |
No | 0 | |
ICU/CCU stay | Yes | 1 |
No | 0 | |
Age >60 years | Yes | 1 |
No | 0 | |
D-dimer ≥2x ULN | Yes | 2 |
No | 0 |
*Immediately prior to and during hospital admission.
Maximum possible score: 14 points (the original 12-point maximum of IMPROVE VTE, plus 2 for elevated D-dimer).
Interpretation
IMPROVEDD Score | 42-day VTE risk | 77-day VTE risk |
0 | 0.4% | 0.5% |
1 | 0.6% | 0.7% |
2 | 0.8% | 1.0% |
3 | 1.2% | 1.4% |
4 | 1.6% | 1.9% |
≥5 | 2.2% | 2.7% |
Risk Categories
In the original derivation study, a simple two-tier cutoff was used, aligned with American College of Chest Physicians (ACCP) guidance recommending prophylaxis at an estimated VTE event rate of ≥1%:
Score | Risk Category |
|---|---|
0–1 | Low risk (prophylaxis generally NOT warranted)
|
≥2 | Increased risk (pharmacologic prophylaxis warranted)
|
Management Considerations
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decsion-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
External Validation in COVID-19
One of the most notable validations of IMPROVEDD came in a large external study of hospitalized COVID-19 patients (Spyropoulos et al., Research and Practice in Thrombosis and Haemostasis, 2021), involving 9,407 patients across a multihospital health system. VTE rates by risk category were:
IMPROVEDD Score | VTE Rate |
|---|---|
0–1 (low) | 0.4% |
2–3 (moderate) | 1.3% |
≥4 (high) | 5.3% |
The model showed good discrimination in this population (ROC AUC 0.70), with roughly 45% of the COVID-19 cohort classified as high VTE risk and 21% as low risk — demonstrating the score's utility in a population (COVID-19) that wasn't part of its original derivation, and reinforcing that elevated thrombotic risk in COVID-19 could be effectively captured using this established framework rather than requiring an entirely new tool.
All questions & possible results
IMPROVEDD risk factorsTitle not visible
Previous VTE
Select one option:
- No
- Yes
Known thrombophilia
Select one option:
- No
- Yes
Current lower-limb paralysis or paresis
Select one option:
- No
- Yes
Current cancer
Select one option:
- No
- Yes
Immobilized ≥7 days
bed rest or sitting, with or without bathroom privileges, immediately prior to and during admission
Select one option:
- No
- Yes
ICU or CCU stay
Select one option:
- No
- Yes
>60 years
Select one option:
- No
- Yes
D-dimer ≥2× the upper limit of normal
Select one option:
- No
- Yes
Possible results
IMPROVEDD Risk Score: 42-day VTE risk 0.6% & 77-day VTE risk 0.7%
The patient is at low risk for VTE. Pharmacologic thromboprophylaxis is NOT warranted. Early ambulation with or without mechanical prophylaxis may be appropriate.
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decision-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
IMPROVEDD Risk Score: 42-day VTE risk 0.8% & 77-day VTE risk 1.0%
The patient is at increased risk for VTE. Start appropriate pharmacologic (e.g., low molecular weight heparin) or mechanical (e.g., compression stockings, intermittent pneumatic compression) prophylaxis.
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decision-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
IMPROVEDD Risk Score: 42-day VTE risk 1.2% & 77-day VTE risk 1.4%
The patient is at increased risk for VTE. Start appropriate pharmacologic (e.g., low molecular weight heparin) or mechanical (e.g., compression stockings, intermittent pneumatic compression) prophylaxis.
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decision-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
IMPROVEDD Risk Score: 42-day VTE risk 1.6% & 77-day VTE risk 1.9%
The patient is at increased risk for VTE. Start appropriate pharmacologic (e.g., low molecular weight heparin) or mechanical (e.g., compression stockings, intermittent pneumatic compression) prophylaxis.
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decision-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
IMPROVEDD Risk Score: 42-day VTE risk 2.2% & 77-day VTE risk 2.7%
The patient is at increased risk for VTE. Start appropriate pharmacologic (e.g., low molecular weight heparin) or mechanical (e.g., compression stockings, intermittent pneumatic compression) prophylaxis.
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decision-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
IMPROVEDD Risk Score: 42-day VTE risk 0.4% & 77-day VTE risk 0.5%
The patient is at low risk for VTE. Pharmacologic thromboprophylaxis is NOT warranted. Early ambulation with or without mechanical prophylaxis may be appropriate.
If pharmacologic prophylaxis is warranted, evaluate for and weigh the risk of bleeding. Consider combining this assessment with the IMPROVE Bleeding Risk Score.
Consider addressing modifiable risk factors for bleeding.
Risk and benefits of anti-coagulation should be considered in patients, to include shared decision-making and informed consent, prior to initiating therapy.
Clinical judgement and best practice guidelines supersede adjunct standalone decision tools.
Clinical Guidelines
Citation
Gibson CM, Spyropoulos AC, Cohen AT, Hull RD, Goldhaber SZ, Yusen RD, Hernandez AF, Korjian S, Daaboul Y, Gold A, Harrington RA, Chi G. The IMPROVEDD VTE Risk Score: Incorporation of D-Dimer into the IMPROVE Score to Improve Venous Thromboembolism Risk Stratification. TH Open. 2017 Jun 28;1(1): e56-e65.
Literature
Gibson CM, Spyropoulos AC, Cohen AT, Hull RD, Goldhaber SZ, Yusen RD, Hernandez AF, Korjian S, Daaboul Y, Gold A, Harrington RA, Chi G. The IMPROVEDD VTE Risk Score: Incorporation of D-Dimer into the IMPROVE Score to Improve Venous Thromboembolism Risk Stratification. TH Open. 2017 Jun 28;1(1):e56-e65.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6524839/Goldin M, Lin SK, Kohn N, Qiu M, Cohen SL, Barish MA, Gianos E, Diaz A, Richardson S, Giannis D, Chatterjee S, Coppa K, Hirsch JS, Ngu S, Firoozan S, McGinn T, Spyropoulos AC. External validation of the IMPROVE-DD risk assessment model for venous thromboembolism among inpatients with COVID-19. J Thromb Thrombolysis. 2021 Nov;52(4):1032-1035.
https://pubmed.ncbi.nlm.nih.gov/34146235/Schünemann HJ, Cushman M, Burnett AE, Kahn SR, Beyer-Westendorf J, Spencer FA, Rezende SM, Zakai NA, Bauer KA, Dentali F, Lansing J, Balduzzi S, Darzi A, Morgano GP, Neumann I, Nieuwlaat R, Yepes-Nuñez JJ, Zhang Y, Wiercioch W. American Society of Hematology 2018 guidelines for management of venous thromboembolism: prophylaxis for hospitalized and nonhospitalized medical patients. Blood Adv. 2018 Nov 27;2(22):3198-3225. doi: 10.1182/bloodadvances.2018022954. Erratum in: Blood Adv. 2023 May 09;7(9):1671.
https://pubmed.ncbi.nlm.nih.gov/30482763/Greco S, Zenunaj G, Bonsi B, Bella A, Lopreiato M, Luciani F, Pedrini D, Vestita G, Dalla Nora E, Passaro A. SARS-CoV-2 and finding of vein thrombosis: can IMPROVE and IMPROVEDD scores predict COVID-19 outcomes? Eur Rev Med Pharmacol Sci. 2021 Feb;25(4):2123-2130.
https://pubmed.ncbi.nlm.nih.gov/33660832/Helmy MA, Milad LM, Hasanin A, Elbasha YS, ElSabbagh HA, Elmarzouky MS, Mostafa M, Abdelhakeem AK, Morsy MAE. Ability of IMPROVE and IMPROVE-DD scores to predict outcomes in patients with severe COVID-19: a prospective observational study. Sci Rep. 2022 Aug 3;12(1):13323.
https://pubmed.ncbi.nlm.nih.gov/35922436/
- Creator
- Provided by
EVAL Foundation
- Contributor · Reviewer
Jennifer Glen, DNP, FNP-BCEVAL Health, Chief Medical Officer EVAL Foundation
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