Caprini Score Calculator
Assess venous thromboembolism risk in surgical and hospitalised patients. The most extensively validated individual VTE risk assessment model, endorsed by ACCP, ASH, and ACS-NSQIP for guiding thromboprophylaxis intensity and duration.
Calculate Caprini Score
Select all risk factors present in the patient. Factors are grouped by point value. Age categories are mutually exclusive — select only the one that applies. The total score determines VTE risk category and recommended prophylaxis strategy.
The Caprini score estimates VTE risk but does not account for bleeding risk. Always perform a concurrent bleeding risk assessment before initiating pharmacological thromboprophylaxis. Patients with active bleeding, severe thrombocytopenia, or recent intracranial haemorrhage may require mechanical prophylaxis alone. Age categories are mutually exclusive — select only the single age bracket that applies.
Understanding the Caprini Score
The Caprini Risk Assessment Model (RAM) was originally developed by Joseph Caprini in 1991 and subsequently refined through multiple iterations. It is an individualised, weighted scoring system that incorporates over 35 patient-specific and procedure-specific risk factors for venous thromboembolism. The current version (2005 update) is the most widely validated VTE risk tool in surgical populations, with studies spanning general surgery, plastic surgery, orthopaedics, vascular surgery, urology, otolaryngology, and gynaecology.
The score was validated in a prospective study of over 8,000 surgical patients at NorthShore University HealthSystem, and has since been externally validated in cohorts totalling over 1.5 million patients (Pannucci et al., Bahl et al.). It forms the basis of VTE prophylaxis protocols in the ACS-NSQIP Surgical Risk Calculator and is endorsed by the ACCP 2012 and ASH 2019 guidelines for surgical thromboprophylaxis.
Scoring Structure
1-point factors (15): Age 41–60, minor surgery, BMI > 25, oedema, varicose veins, pregnancy/postpartum, OCP/HRT, sepsis, lung disease, COPD, acute MI, CHF, IBD, bed rest, recurrent abortion
2-point factors (8): Age 61–74, major/arthroscopic/laparoscopic surgery (>45 min), malignancy, bed confinement >72h, immobilising cast, CVC
3-point factors (10): Age ≥75, VTE history, family VTE, thrombophilias (FVL, PT 20210A, APLA, lupus anticoagulant, homocysteine, HIT, other)
5-point factors (4): Recent stroke, major arthroplasty, hip/pelvis/leg fracture, spinal cord injury
Why Caprini Over Padua or Wells?
The Padua score is validated for medical patients and should not be used for surgical risk assessment. The Wells score is a diagnostic tool for suspected acute DVT or PE — not a prophylaxis risk assessment tool. The Caprini score is specifically designed and validated for surgical and perioperative VTE risk stratification.
Caprini uniquely captures procedure-specific risk (surgery type and duration), inherited thrombophilias, and hormonal factors, making it the most comprehensive surgical VTE risk model available.
Key principle: The Caprini score is additive — most surgical patients will accumulate multiple risk factors. A 65-year-old patient with cancer undergoing a major open abdominal procedure already scores 6 (age 61–74 = 2, malignancy = 2, major surgery = 2) before considering any additional comorbidities. This is why Caprini effectively identifies the majority of surgical patients as moderate-to-high risk, which aligns with evidence that most surgical patients benefit from some form of thromboprophylaxis.
Risk Categories & Prophylaxis Recommendations
| Caprini Score | Risk Category | VTE Incidence | Recommended Prophylaxis |
|---|---|---|---|
| 0 | Very low | ~0.5% | Early ambulation only; no pharmacological or mechanical prophylaxis required |
| 1–2 | Low | ~1.5% | Mechanical prophylaxis: IPC (intermittent pneumatic compression) devices |
| 3–4 | Moderate | ~3.0% | Pharmacological prophylaxis (LMWH or UFH) + IPC; or IPC alone if high bleeding risk |
| 5–8 | High | ~6.0% | Pharmacological + mechanical prophylaxis; consider extended-duration prophylaxis post-discharge |
| ≥ 9 | Very high (super high-risk) | ~11.3% | Pharmacological + mechanical prophylaxis; extended prophylaxis (up to 4 weeks post-discharge) strongly recommended |
VTE incidence rates are approximate, derived from pooled data across validation studies. Actual rates vary by surgical specialty, procedure type, and institution. Extended-duration prophylaxis (typically 28–35 days post-discharge) is most strongly supported for abdominal/pelvic cancer surgery (ENOXACAN II) and major orthopaedic surgery (hip/knee arthroplasty, hip fracture repair).
In the Bahl et al. validation study of over 1.1 million surgical patients, VTE rates for Caprini ≥ 9 were four times higher than Caprini 5–8, and the super-high-risk group (≥9) derived the greatest absolute benefit from pharmacological prophylaxis. If a patient scores ≥ 9, ensure both pharmacological and mechanical prophylaxis are in place and strongly consider extended-duration post-discharge prophylaxis with LMWH or a DOAC.
Thromboprophylaxis Options & Bleeding Risk
LMWH (enoxaparin, dalteparin, tinzaparin) is the most widely used pharmacological agent for surgical VTE prophylaxis. Standard prophylactic doses include enoxaparin 40 mg SC once daily (or 30 mg SC twice daily for high-risk orthopaedic patients) and dalteparin 5,000 IU SC once daily. LMWH is preferred over UFH in most settings due to superior efficacy, once-daily dosing, and lower risk of HIT.
Unfractionated heparin (UFH) 5,000 IU SC every 8–12 hours is an alternative when LMWH is unavailable, in severe renal impairment (CrCl < 30 mL/min), or when rapid reversibility is needed. Three-times-daily dosing (q8h) may be more effective than twice-daily (q12h) in high-risk surgical patients.
DOACs (rivaroxaban 10 mg daily, apixaban 2.5 mg twice daily) are approved for VTE prophylaxis after elective hip or knee arthroplasty and are increasingly used in other high-risk surgical settings. They offer the convenience of oral administration post-discharge but have limited evidence outside orthopaedic surgery.
Intermittent pneumatic compression (IPC) devices are the preferred mechanical prophylaxis modality. They reduce VTE by enhancing venous return and stimulating endogenous fibrinolysis. IPC is indicated as sole prophylaxis in low-risk patients (Caprini 1–2) and as an adjunct to pharmacological prophylaxis in moderate-to-high-risk patients. They are the only option when pharmacological prophylaxis is contraindicated due to bleeding risk.
Graduated compression stockings (GCS) provide modest VTE risk reduction and are less effective than IPC. They may be used as an adjunct but should not be relied upon as sole prophylaxis in patients with Caprini ≥ 3. Contraindications include peripheral arterial disease (ABI < 0.8), peripheral neuropathy, dermatitis, and recent skin grafts.
The key limitation of mechanical prophylaxis is compliance — devices must be worn continuously (not just during the day) to be effective, and compliance rates in clinical practice are often poor.
The Caprini score estimates VTE risk but does not assess bleeding risk. Before initiating pharmacological prophylaxis, evaluate for active bleeding, severe thrombocytopenia (platelets < 50,000), coagulopathy (INR > 1.5), lumbar puncture/epidural within 12 hours, intracranial haemorrhage, or other procedure-specific bleeding concerns.
The IMPROVE bleeding risk score (for medical patients) and the Caprini-ACCP framework (assess benefit vs. risk) can guide this decision. When bleeding risk is high: use mechanical prophylaxis (IPC) alone initially, then reassess for pharmacological prophylaxis when bleeding risk decreases. When thrombotic risk is high AND bleeding risk is high: IPC is essential, and pharmacological prophylaxis should be started as soon as surgically safe (typically 12–24 hours postoperatively).
Standard in-hospital prophylaxis may be insufficient for the highest-risk patients. VTE risk persists for weeks after major surgery, with a peak at days 3–7 but continued risk for up to 6 weeks. Extended-duration prophylaxis (28–35 days total) is recommended for: major abdominal/pelvic cancer surgery (ACCP Grade 1B, based on ENOXACAN II trial), elective hip arthroplasty (up to 35 days), elective knee arthroplasty (up to 14 days), and hip fracture surgery (up to 35 days).
For patients with Caprini ≥ 9 undergoing non-orthopaedic major surgery, extended prophylaxis should be strongly considered, though evidence is less robust outside cancer surgery. LMWH or rivaroxaban 10 mg daily are common choices for extended-duration post-discharge prophylaxis.
Special Populations & Considerations
Renal impairment: Enoxaparin accumulates in severe renal impairment (CrCl < 30 mL/min) and requires dose adjustment (e.g., enoxaparin 30 mg SC once daily) or substitution with UFH 5,000 IU SC q8–12h. DOACs require dose adjustment or avoidance depending on CrCl. Always check renal function before prescribing pharmacological VTE prophylaxis.
Stepwise VTE Prophylaxis Workflow
Calculate the Caprini score for every patient admitted for surgery or a surgical procedure. This should be part of the admission or preoperative checklist. Review all risk factor categories systematically — many factors (thrombophilias, family history, prior VTE) are easily missed without a structured tool. Document the score in the medical record.
Before prescribing pharmacological prophylaxis, evaluate bleeding risk: active haemorrhage, recent intracranial bleed, severe thrombocytopenia, major trauma with bleeding, planned spinal/epidural anaesthesia (timing restrictions), or surgeon-specific bleeding concerns. If bleeding risk is high, start with IPC alone and reassess daily for readiness to add pharmacological prophylaxis. The decision to withhold chemical prophylaxis should be explicit, documented, and time-limited.
Score 0: Early ambulation only. Score 1–2: IPC devices. Score 3–4: LMWH or UFH + IPC (or IPC alone if high bleeding risk). Score ≥ 5: LMWH/UFH + IPC; discuss extended-duration post-discharge prophylaxis. Ensure the first dose of pharmacological prophylaxis is timed appropriately relative to surgery and neuraxial anaesthesia (typically 2 hours preop for UFH; 12 hours preop for LMWH; or 6–12 hours postop for both).
VTE risk and bleeding risk are dynamic. Reassess daily during the admission: has the bleeding risk decreased (allowing pharmacological prophylaxis to start)? Has the patient become more immobile (increasing risk)? Has a new complication (sepsis, ICU admission) developed? At discharge, determine whether extended-duration prophylaxis is indicated (Caprini ≥ 5, cancer surgery, orthopaedic arthroplasty) and ensure a clear plan is documented for the patient and the outpatient team.
Common Pitfalls & Limitations
VTE prophylaxis omission is one of the most common preventable causes of hospital-acquired harm. Studies show that 30–50% of surgical patients who should receive thromboprophylaxis do not. The most frequent reason is failure to perform a formal risk assessment. Many clinicians rely on clinical gestalt (“the patient is young and mobile”) rather than a structured tool, leading to underestimation of risk. Institutional protocols should mandate Caprini scoring for every surgical admission.
The Caprini score was developed and validated for surgical patients. Applying it to medical inpatients (e.g., pneumonia, CHF exacerbation, stroke without surgery) may overestimate risk because the surgical-specific factors are irrelevant. For medical patients, use the Padua Prediction Score or the IMPROVE VTE risk model, both of which are validated in non-surgical hospitalised populations. Similarly, the Wells score is a diagnostic tool for suspected acute VTE and should not be used for prophylaxis risk assessment.
The three age categories (41–60, 61–74, ≥75) are mutually exclusive. A 78-year-old patient receives 3 points for age ≥ 75 only — not 3 + 2 + 1 = 6. Selecting more than one age category is a common scoring error that inflates the score and may trigger inappropriate escalation of prophylaxis. Similarly, the four surgery-type options (minor, major open, arthroscopic, laparoscopic) should reflect the actual planned procedure — select only the one that applies.
Many VTE events occur after hospital discharge, with risk persisting for 4–6 weeks after major surgery. Standard in-hospital-only prophylaxis leaves a significant risk window uncovered, particularly for cancer surgery and orthopaedic arthroplasty patients. Patients with Caprini ≥ 5 should be actively assessed at discharge for extended-duration prophylaxis. The ENOXACAN II trial demonstrated that 4 weeks of LMWH reduced VTE by 60% after major abdominal cancer surgery compared with 1 week alone.
IPC devices are effective only when worn continuously — yet studies show compliance rates of 40–60% in many hospitals. Common reasons include patient discomfort, devices being removed for mobilisation and not reapplied, nursing workload, and equipment availability. When auditing VTE prophylaxis quality, compliance with mechanical prophylaxis should be tracked alongside pharmacological prescribing. IPC devices should be applied in the preoperative area and maintained until the patient is fully ambulatory.
Quick Reference Summary
in the Caprini model
mechanical prophylaxis
duration (high risk)
validation studies
| Score | Risk | VTE Rate | Prophylaxis | Extended? |
|---|---|---|---|---|
| 0 | Very low | ~0.5% | Early ambulation | No |
| 1–2 | Low | ~1.5% | IPC | No |
| 3–4 | Moderate | ~3.0% | LMWH/UFH + IPC | Seldom |
| 5–8 | High | ~6.0% | LMWH/UFH + IPC | Consider |
| ≥ 9 | Very high | ≥ 11% | LMWH/UFH + IPC | Strongly rec. |
The Golden Rule: Score every surgical patient. Assess bleeding risk. Prescribe prophylaxis matched to the risk tier. Reassess daily and at discharge. VTE prophylaxis omission is the most common preventable cause of hospital-acquired harm in surgical patients — a structured Caprini-based protocol is the single most effective intervention to prevent it.
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
- Caprini JA. Thrombosis risk assessment as a guide to quality patient care. Disease-a-Month. 2005;51(2-3):70-78. DOI: 10.1016/j.disamonth.2005.02.003
- Bahl V, Hu HM, Henke PK, Wakefield TW, Campbell DA Jr, Caprini JA. A validation study of a retrospective venous thromboembolism risk scoring method. Annals of Surgery. 2010;251(2):344-350. DOI: 10.1097/SLA.0b013e3181b7fca6
- Pannucci CJ, Swistun L, MacDonald JK, Henke PK, Brooke BS. Individualized venous thromboembolism risk stratification using the 2005 Caprini score to identify the benefits and harms of chemoprophylaxis in surgical patients. Annals of Surgery. 2017;265(6):1094-1103. DOI: 10.1097/SLA.0000000000002126
- Gould MK, Garcia DA, Wren SM, et al. Prevention of VTE in nonorthopedic surgical patients: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: ACCP Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(2 Suppl):e227S-e277S. DOI: 10.1378/chest.11-2297
- Anderson DR, Morgano GP, Bennett C, et al. American Society of Hematology 2019 guidelines for management of venous thromboembolism: prevention of venous thromboembolism in surgical hospitalized patients. Blood Advances. 2019;3(23):3898-3944. DOI: 10.1182/bloodadvances.2019000975
- Bergqvist D, Agnelli G, Cohen AT, et al. Duration of prophylaxis against venous thromboembolism with enoxaparin after surgery for cancer (ENOXACAN II). New England Journal of Medicine. 2002;346(13):975-980. DOI: 10.1056/NEJMoa012385
- Falck-Ytter Y, Francis CW, Johanson NA, et al. Prevention of VTE in orthopedic surgery patients: ACCP Evidence-Based Clinical Practice Guidelines (9th Edition). Chest. 2012;141(2 Suppl):e278S-e325S. DOI: 10.1378/chest.11-2404
- Caprini JA, Arcelus JI, Hasty JH, Tamhane AC, Fabrega F. Clinical assessment of venous thromboembolic risk in surgical patients. Seminars in Thrombosis and Hemostasis. 1991;17(Suppl 3):304-312.
- Anderson FA Jr, Spencer FA. Risk factors for venous thromboembolism. Circulation. 2003;107(23 Suppl 1):I9-I16. DOI: 10.1161/01.CIR.0000078469.07362.E6
- Laryea J, Engel JM, Engel JM. Year of the Caprini score: what the latest literature says. Seminars in Thrombosis and Hemostasis. 2023;49(4):395-404. DOI: 10.1055/s-0042-1757183