Padua Prediction Score Calculator
Assess venous thromboembolism risk in hospitalised medical patients. The validated tool for guiding pharmacological thromboprophylaxis decisions in non-surgical inpatients, endorsed by ACCP and NICE guidelines.
Calculate Padua Prediction Score
Select all risk factors present at the time of admission. The score has a single clinically actionable threshold: ≥ 4 points = high VTE risk, warranting pharmacological prophylaxis. Always assess bleeding risk concurrently before prescribing anticoagulant prophylaxis.
The Padua score is validated for medical (non-surgical) inpatients only. For surgical patients, use the Caprini score instead. The Padua score does not assess bleeding risk — always perform a concurrent bleeding risk evaluation (e.g., IMPROVE Bleeding Risk Score) before initiating pharmacological prophylaxis. Mechanical prophylaxis should be used when pharmacological prophylaxis is contraindicated.
Understanding the Padua Prediction Score
The Padua Prediction Score was developed by Barbar et al. in 2010 at the University of Padua, Italy, from a prospective cohort of 1,180 consecutive medical patients admitted to an internal medicine department. It was designed to address a specific clinical gap: while surgical VTE prophylaxis was well established, evidence-based risk assessment tools for medical patients were lacking, leading to widespread under- and over-prophylaxis.
The score incorporates 11 risk factors weighted by their relative contribution to VTE risk. Three factors carry the highest weight (3 points each): active cancer, previous VTE, and reduced mobility — reflecting the classical Virchow triad of hypercoagulability, prior endothelial injury, and stasis. The single threshold of ≥ 4 points creates a binary classification (low vs. high risk) that directly maps to a prophylaxis decision, making it practical for routine clinical use.
Score Components
3 points: Active cancer, previous VTE, reduced mobility (≥3 days bed rest)
2 points: Known thrombophilia
1 point: Recent trauma/surgery (≤1 mo), age ≥70, heart/respiratory failure, acute MI/stroke, acute infection/rheumatological disorder, obesity (BMI ≥30), hormonal treatment
Maximum score: 20. Actionable threshold: ≥ 4 = high risk.
Padua vs. Other Medical VTE Tools
IMPROVE VTE: An alternative model developed from a multinational registry of 15,000 medical patients. Uses 7 factors and a threshold of ≥ 2. Validated in broader populations but less widely adopted in guidelines than Padua.
Caprini: For surgical patients only. Should not be applied to medical admissions.
Padua remains the most commonly referenced medical VTE risk tool in ACCP 2012, NICE 2018, and ASH 2018 guidelines.
Key validation finding: In the original Barbar et al. study, patients with Padua ≥ 4 who did not receive prophylaxis had a 90-day VTE rate of 11.0%, compared with only 2.2% in those who received pharmacological prophylaxis — an 80% relative risk reduction. Patients with Padua < 4 had a VTE rate of only 0.3% regardless of prophylaxis, confirming that low-risk patients derive minimal benefit from anticoagulant prophylaxis.
Risk Categories & Prophylaxis Decision
| Padua Score | Risk Category | 90-Day VTE Rate (No Prophylaxis) | Action |
|---|---|---|---|
| < 4 | Low risk | ~0.3% | No pharmacological prophylaxis; encourage early and frequent ambulation |
| ≥ 4 | High risk | ~11.0% | Pharmacological prophylaxis recommended (if no contraindications); add mechanical prophylaxis (IPC) |
The binary threshold simplifies the clinical decision: < 4 = no prophylaxis needed; ≥ 4 = prophylaxis recommended. This approach avoids the complexity of multi-tier systems while maintaining clinical accuracy. The 11% VTE rate in high-risk unprophylaxed patients is clinically substantial and preventable.
IMPROVE Bleeding Risk Score — The Mandatory Companion
| IMPROVE Bleeding Factor | Points |
|---|---|
| Active gastroduodenal ulcer | 4.5 |
| Bleeding in 3 months before admission | 4 |
| Platelet count < 50 × 10⁹/L | 4 |
| Age ≥ 85 years | 3.5 |
| Hepatic failure (INR > 1.5) | 2.5 |
| Severe renal failure (GFR < 30 mL/min/m²) | 2.5 |
| ICU/CCU admission | 2.5 |
| Central venous catheter | 2 |
| Rheumatic disease | 2 |
| Current cancer | 2 |
| Male sex | 1 |
An IMPROVE Bleeding Score ≥ 7 indicates high bleeding risk. When both Padua ≥ 4 and IMPROVE Bleeding ≥ 7, use mechanical prophylaxis (IPC) alone until the bleeding risk decreases, then reassess for pharmacological prophylaxis.
The net clinical benefit of pharmacological prophylaxis in medical patients is narrower than in surgical patients. The APEX, MAGELLAN, and MARINER trials showed that extended-duration prophylaxis in medical patients reduced VTE but increased bleeding, with no net survival benefit. This is why restricting prophylaxis to Padua ≥ 4 (proven benefit) and checking IMPROVE bleeding risk (proven safety check) is critical — blanket prophylaxis of all medical inpatients is not supported by evidence.
Prophylaxis Options & Key Trial Evidence
Enoxaparin 40 mg SC once daily is the most widely used agent for medical VTE prophylaxis, supported by the MEDENOX trial (63% relative risk reduction in VTE vs. placebo). Dalteparin 5,000 IU SC once daily is an equivalent alternative (PREVENT trial). Fondaparinux 2.5 mg SC once daily is a synthetic factor Xa inhibitor option (ARTEMIS trial), particularly useful in patients with a history of HIT.
UFH 5,000 IU SC q8h or q12h is an alternative in severe renal impairment (CrCl < 30 mL/min), though some data suggest three-times-daily dosing is more effective than twice-daily. Duration is typically for the period of hospitalisation or until the patient is fully ambulatory — not extended post-discharge for standard medical patients.
Unlike surgical prophylaxis (where extended duration is established), extended prophylaxis for medical patients remains controversial. The EXCLAIM trial (enoxaparin 28 days vs. 10 days) showed reduced VTE but increased major bleeding. The MAGELLAN trial (rivaroxaban 35 days vs. enoxaparin 10 days) showed similar results. The MARINER trial (rivaroxaban 45 days post-discharge) reduced fatal VTE but did not reduce the primary composite endpoint and increased bleeding.
Current consensus: extended-duration prophylaxis is not routinely recommended for medical patients. It may be considered in selected very-high-risk patients (e.g., Padua ≥ 4 with active cancer and prolonged immobility) if bleeding risk is low, but this remains an area of active research rather than established practice.
Intermittent pneumatic compression (IPC) devices are the primary mechanical prophylaxis option for medical patients with high VTE risk but contraindications to anticoagulation. The CLOTS 3 trial (in stroke patients) demonstrated that IPC reduced DVT significantly compared with no IPC. IPC should be applied from the time of admission and worn continuously until the patient is fully ambulatory or until pharmacological prophylaxis can be safely initiated.
Graduated compression stockings (GCS) alone have limited evidence in medical patients and are not recommended as sole prophylaxis by most guidelines. The CLOTS 1 trial showed no significant VTE reduction with GCS in stroke patients, and they were associated with skin complications. GCS may be used as an adjunct to IPC or pharmacological prophylaxis but should not replace either.
Absolute contraindications include: active major bleeding, severe uncontrolled hypertension (systolic > 200 mmHg), recent intracranial haemorrhage (within 30 days), severe thrombocytopenia (platelets < 25,000), untreated inherited bleeding disorders, and concurrent full-dose therapeutic anticoagulation (already sufficient).
Relative contraindications requiring careful judgement include: platelets 25,000–50,000, coagulopathy (INR > 1.5), recent GI bleeding (within 3 months), hepatic failure, planned invasive procedure within 12 hours, and lumbar puncture/epidural within 12 hours. In these situations, use mechanical prophylaxis (IPC) and reassess daily for readiness to add pharmacological prophylaxis.
Special Populations & Considerations
COVID-19 and VTE: The COVID-19 pandemic highlighted the heightened thrombotic risk in acutely ill medical patients. Hospitalised COVID-19 patients typically score high on Padua (infection +1, immobility +3, often respiratory failure +1, age ≥70 +1). Standard-dose LMWH prophylaxis is recommended for all hospitalised COVID-19 patients. The ATTACC/ACTIV-4a/REMAP-CAP platform trials showed that therapeutic-dose anticoagulation improved outcomes in moderately ill (non-ICU) COVID-19 patients but was harmful in the critically ill (ICU) subgroup.
Stepwise Medical VTE Prophylaxis Workflow
The Padua score applies to patients admitted under medical services (internal medicine, cardiology, respiratory, neurology, oncology, etc.) who are not undergoing surgery during the admission. If the patient is admitted for a surgical procedure, use the Caprini score instead. If a medical patient subsequently undergoes an unplanned procedure, reassess using the Caprini framework for the post-surgical period.
Systematically assess all 11 risk factors at the time of admission. Pay particular attention to the three high-weight factors: active cancer (check recent treatment history), prior VTE (specifically excluding superficial vein thrombosis), and anticipated reduced mobility (≥ 3 days bed rest). Document the score in the admission notes. Score < 4 = low risk; ≥ 4 = high risk.
For patients with Padua ≥ 4, calculate the IMPROVE Bleeding Risk Score (or perform a structured bleeding risk assessment). If IMPROVE < 7 and no absolute contraindications: prescribe pharmacological prophylaxis. If IMPROVE ≥ 7 or absolute contraindications present: use mechanical prophylaxis (IPC) alone and reassess daily. Document the bleeding risk assessment and the rationale for the prophylaxis decision.
Padua < 4: Encourage early and frequent ambulation. No pharmacological or mechanical prophylaxis required. Padua ≥ 4, low bleeding risk: Enoxaparin 40 mg SC once daily (or dalteparin 5,000 IU, or fondaparinux 2.5 mg, or UFH 5,000 IU q8h). Consider IPC as adjunct. Padua ≥ 4, high bleeding risk: IPC alone until bleeding risk subsides; reassess daily. Duration is typically for the hospitalisation period or until full ambulation — not extended post-discharge for standard medical patients.
Risk factors are dynamic. Daily reassessment should address: has mobility improved (reducing immobility risk)? Has bleeding risk decreased (allowing pharmacological prophylaxis to start)? Has a new VTE risk factor developed (new procedure, new CVC, worsening immobility)? At discharge, discontinue prophylaxis for standard medical patients. Consider extended prophylaxis only in selected very-high-risk patients (active cancer with ongoing immobility, prior VTE) after careful bleeding risk evaluation.
Common Pitfalls & Limitations
Prescribing pharmacological VTE prophylaxis to every medical inpatient regardless of risk is not evidence-based and exposes low-risk patients to bleeding without meaningful benefit. In the Barbar et al. validation study, patients with Padua < 4 had a 90-day VTE rate of only 0.3% — prophylaxis in this group provides negligible absolute risk reduction while adding bleeding risk. The net clinical benefit is negative. Structured Padua-based assessment ensures prophylaxis reaches those who benefit (≥ 4) while sparing those who do not (< 4).
The Padua score was derived and validated exclusively in medical inpatients. It does not capture surgical-specific risk factors (procedure type, duration, operative positioning, anaesthesia type) that are critical for surgical VTE risk. Applying Padua to a patient admitted for major abdominal surgery will underestimate their risk. Use the Caprini score for surgical patients. Similarly, the Caprini score should not be used for medical admissions.
A Padua score ≥ 4 indicates the patient is at high VTE risk, but it says nothing about their bleeding risk. Prescribing enoxaparin to a patient with active GI bleeding, platelets of 30,000, or a recent intracranial haemorrhage would be harmful. Every Padua ≥ 4 patient must have a concurrent bleeding risk assessment (IMPROVE Bleeding Score or equivalent) before pharmacological prophylaxis is started. If bleeding risk is high, IPC is the appropriate alternative until the risk decreases.
The “previous VTE” criterion (3 points) explicitly excludes superficial vein thrombosis (SVT). Only prior deep vein thrombosis (DVT) or pulmonary embolism (PE) counts. SVT is common, particularly in patients with varicose veins or recent IV cannulation, and incorrectly scoring it as prior VTE inflates the score by 3 points — potentially pushing a patient from low to high risk unnecessarily. Verify the type of prior venous event before scoring.
Padua risk is calculated at admission but the patient’s status is dynamic. A patient admitted ambulatory (no immobility points) who subsequently deteriorates and becomes bedbound may now qualify for prophylaxis. Conversely, a patient who was immobilised but recovers mobility may no longer need prophylaxis. The score should be reassessed whenever there is a significant change in clinical status — not treated as a static one-time calculation.
Quick Reference Summary
(prophylaxis recommended)
high-risk & no prophylaxis
low-risk patients
with prophylaxis (high-risk)
| Padua Score | Risk | Bleeding Risk OK? | Action |
|---|---|---|---|
| < 4 | Low | N/A | Early ambulation; no prophylaxis needed |
| ≥ 4 | High | Yes (IMPROVE < 7) | LMWH/UFH/fondaparinux + consider IPC |
| ≥ 4 | High | No (IMPROVE ≥ 7) | IPC alone; reassess daily for chemical prophylaxis |
The Golden Rule: Padua answers one question: does this medical inpatient need pharmacological VTE prophylaxis? Score < 4 = no. Score ≥ 4 = yes, if bleeding risk is acceptable. Always pair Padua (VTE risk) with IMPROVE (bleeding risk) to make a balanced, evidence-based decision. And remember: Padua is for medical patients; Caprini is for surgical patients. Using the wrong tool for the wrong population is a common and avoidable error.
Disclaimer & References
For Educational Purposes Only. This calculator and the accompanying clinical information are intended as educational tools for healthcare professionals. They do not replace clinical judgement. Results should be interpreted in the full clinical context. Lab reference ranges vary by institution — verify with your own laboratory. Drug dosages should be confirmed against current prescribing information.
References
- Barbar S, Noventa F, Rossetto V, et al. A risk assessment model for the identification of hospitalized medical patients at risk for venous thromboembolism: the Padua Prediction Score. Journal of Thrombosis and Haemostasis. 2010;8(11):2450-2457. DOI: 10.1111/j.1538-7836.2010.04044.x
- Kahn SR, Lim W, Dunn AS, et al. Prevention of VTE in nonsurgical patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: ACCP Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(2 Suppl):e195S-e226S. DOI: 10.1378/chest.11-2296
- Samama MM, Cohen AT, Darmon JY, et al. A comparison of enoxaparin with placebo for the prevention of venous thromboembolism in acutely ill medical patients (MEDENOX). New England Journal of Medicine. 1999;341(11):793-800. DOI: 10.1056/NEJM199909093411103
- Leizorovicz A, Cohen AT, Turpie AG, Olsson CG, Vaitkus PT, Goldhaber SZ. Randomized, placebo-controlled trial of dalteparin for the prevention of venous thromboembolism in acutely ill medical patients (PREVENT). Circulation. 2004;110(7):874-879. DOI: 10.1161/01.CIR.0000138928.83266.24
- Decousus H, Tapson VF, Bergmann JF, et al. Factors at admission associated with bleeding risk in medical patients: findings from the IMPROVE investigators. Chest. 2011;139(1):69-79. DOI: 10.1378/chest.09-3081
- CLOTS (Clots in Legs Or sTockings after Stroke) Trials Collaboration. Effectiveness of intermittent pneumatic compression in reduction of risk of deep vein thrombosis in patients who have had a stroke (CLOTS 3). The Lancet. 2013;382(9891):516-524. DOI: 10.1016/S0140-6736(13)61050-8
- Spyropoulos AC, Ageno W, Albers GW, et al. Rivaroxaban for thromboprophylaxis after hospitalization for medical illness (MARINER). New England Journal of Medicine. 2018;379(12):1118-1127. DOI: 10.1056/NEJMoa1805090
- ATTACC Investigators, ACTIV-4a Investigators, REMAP-CAP Investigators, et al. Therapeutic anticoagulation with heparin in noncritically ill patients with COVID-19. New England Journal of Medicine. 2021;385(9):790-802. DOI: 10.1056/NEJMoa2105911
- Schünemann HJ, Cushman M, Burnett AE, et al. American Society of Hematology 2018 guidelines for management of venous thromboembolism: prophylaxis for hospitalized and nonhospitalized medical patients. Blood Advances. 2018;2(22):3198-3225. DOI: 10.1182/bloodadvances.2018022954
- National Institute for Health and Care Excellence (NICE). Venous thromboembolism in over 16s: reducing the risk of hospital-acquired deep vein thrombosis or pulmonary embolism (NG89). 2018. Available at: nice.org.uk/guidance/ng89