What is the Caprini Score?
The Caprini score is a venous thromboembolism (VTE) risk assessment tool that stratifies surgical patients into four risk categories by assigning points (1-5) to approximately 20 different risk factors, with total scores correlating to VTE risk: very low (0 points; 0.5% risk), low (1-2 points; 1.5% risk), moderate (3-4 points; 3% risk), and high (≥5 points; 6% risk). 1
How the Scoring System Works
The Caprini model assigns weighted points to various patient and procedural risk factors 1:
- 1 point factors include minor surgery, varicose veins, history of inflammatory bowel disease, obesity (BMI >25), and other moderate risk factors 1
- 2 point factors include arthroscopic surgery, major open surgery >45 minutes, laparoscopic surgery >45 minutes, malignancy, and confined to bed >72 hours 1
- 3 point factors include history of VTE, family history of VTE, positive Factor V Leiden, and other thrombophilias 1
- 5 point factors include stroke <1 month, elective lower extremity arthroplasty, hip/pelvis/leg fracture, and acute spinal cord injury <1 month 1
Risk Categories and Associated VTE Rates
The American College of Chest Physicians (ACCP) guidelines define four risk categories based on Caprini scores 1:
- Very low risk: Score 0-1 (VTE risk <0.5%) 1
- Low risk: Score 1-2 (VTE risk ~1.5%) 1
- Moderate risk: Score 3-4 (VTE risk ~3.0%) 1
- High risk: Score ≥5 (VTE risk ~6.0%) 1
For extremely high-risk patients with scores ≥11, VTE risk increases dramatically to approximately 59-65% 2, suggesting these patients may need more aggressive prophylaxis beyond standard regimens.
Clinical Application
The Caprini score is primarily used for nonorthopedic surgical patients, particularly those undergoing general, abdominal, pelvic, thoracic, and spinal surgery 1. The ACCP guidelines recommend using the Caprini method to guide VTE prophylaxis decisions in these populations 1.
The score guides prophylaxis selection as follows 1:
- Very low risk (0-1): Early ambulation only, no pharmacologic or mechanical prophylaxis needed 1
- Low risk (1-2): Mechanical prophylaxis with intermittent pneumatic compression (IPC) preferred 1
- Moderate risk (3-4): LMWH, low-dose unfractionated heparin (LDUH), or IPC 1
- High risk (≥5): LMWH or LDUH plus mechanical prophylaxis with elastic stockings or IPC 1
For high-risk patients undergoing cancer surgery (abdominal or pelvic), extended-duration prophylaxis with LMWH for 4 weeks is recommended 1, rather than the standard 10-14 days 1.
Important Limitations and Caveats
The Caprini score was not developed using rigorous statistical methods and includes some variables later found not to be associated with VTE risk 1. However, it remains relatively easy to use and discriminates reasonably well among risk categories 1.
Significant heterogeneity exists in how the Caprini score is implemented across centers 3, including variability in the number of risk categories used (2-5 categories), cutoff scores defining categories, and follow-up duration (0-180 days versus the intended 30 days) 3. This leads to similar risk categories being associated with different VTE rates across studies 3.
The Caprini score has limited validation in orthopedic surgery patients 1. Studies in total joint arthroplasty patients show the score does not provide clinically useful risk stratification in this population 4, 5, with small effect sizes and poor predictive power when controlling for prophylaxis 4.
A patient-completed version of the Caprini score has been validated with excellent agreement (r=0.95) compared to physician-completed forms 6, though BMI calculation should be performed by the physician 6. This can reduce physician time burden while maintaining accuracy 6.