Caprini Score Calculation and VTE Prophylaxis
Use the Caprini risk assessment model to stratify surgical patients into four risk categories (very low 0 points/0.5%, low 1-2 points/1.5%, moderate 3-4 points/3%, high ≥5 points/6%), then apply risk-stratified pharmacologic prophylaxis with LMWH or unfractionated heparin combined with mechanical prophylaxis for moderate-to-high risk patients without bleeding contraindications 1.
Calculating the Caprini Score
The Caprini risk assessment model assigns points based on patient and procedure-specific risk factors. While the evidence doesn't provide the complete scoring table, the key principle is additive risk stratification:
- Score 0: Very low risk (0.5% VTE rate)
- Score 1-2: Low risk (1.5% VTE rate)
- Score 3-4: Moderate risk (3% VTE rate)
- Score ≥5: High risk (6% VTE rate)
Critical threshold: A Caprini score of ≥11 identifies extremely high-risk patients who develop VTE in 59% of cases despite standard prophylaxis, compared to only 3% in patients with scores <11 2. These patients require more aggressive prophylactic regimens.
Risk-Stratified Prophylaxis Algorithm
For Nonorthopedic Surgery Patients
Moderate-to-High Risk (Score 3-4 or ≥5) without bleeding risk:
- LMWH (enoxaparin 40 mg SC once daily OR dalteparin 5000 IU SC once daily) combined with intermittent pneumatic compression
- Start 2-4 hours preoperatively or 10-12 hours preoperatively
- Continue for minimum 7-10 days
- Extend to 4 weeks for high-risk patients, particularly those with cancer 1
High bleeding risk:
- Use mechanical prophylaxis (intermittent pneumatic compression) alone until bleeding risk diminishes
- Then add pharmacologic prophylaxis 1
Very Low to Low Risk (Score 0-2):
- Early ambulation
- Consider mechanical prophylaxis only
Specific Dosing Regimens
Enoxaparin:
- Surgical patients: 40 mg SC once daily (or 30 mg SC twice daily for orthopedic surgery)
- Medical patients: 40 mg SC once daily 3, 1
Dalteparin:
- Low risk surgery: 2500 IU SC once daily
- High risk surgery: 2500 IU 2-4 hours preoperatively, then 5000 IU SC once daily 3, 1
Unfractionated heparin:
- 5000 U SC every 8 hours (preferred over every 12 hours dosing which is less effective)
- Particularly for cancer patients 3, 1
Fondaparinux:
- 2.5 mg SC once daily beginning 6-8 hours postoperatively
- Reduce to 1.5 mg once daily if creatinine clearance 30-50 mL/min 1
Special Populations
Cancer Patients
Cancer patients require 4 weeks of LMWH prophylaxis after major surgery due to persistently elevated thrombotic risk 1. Hospitalized medical cancer patients with active malignancy and additional risk factors should receive pharmacologic thromboprophylaxis 4, 3.
Renal Impairment
- CrCl >30 mL/min: Standard LMWH dosing
- CrCl 15-30 mL/min: Reduce enoxaparin to 2000 IU every 12-24 hours OR use unfractionated heparin
- CrCl <15 mL/min: Unfractionated heparin 5000 U every 8-12 hours 5
Bariatric/Obese Patients
Consider higher LMWH doses for patients with BMI ≥35 kg/m² 6, 7. Monitor anti-Xa levels to ensure adequate dosing in morbidly obese patients 7.
Extended Duration Prophylaxis
Continue prophylaxis after discharge for 4 weeks in:
- Patients with Caprini score ≥9 8
- Cancer surgery patients 3, 1
- Patients with prolonged hospital stay, postoperative sepsis, or urinary tract infection 7
The Caprini score effectively identifies which patients benefit from extended prophylaxis, avoiding unnecessary treatment in lower-risk patients 8, 9.
Critical Validation Data
The Caprini model demonstrates strong predictive validity: patients with scores 9-11 have an 18.7-fold increased DVT risk, while scores 12-15 have a 98.4-fold increased risk compared to scores 5-8 2. The area under the ROC curve is 0.87, indicating excellent discriminatory ability 2.
In bariatric surgery, appropriate Caprini-guided prophylaxis reduced VTE events without increasing bleeding complications 9. In arthroplasty, the 2013 Caprini model correctly identified 7 of 8 VTE events retrospectively 10.
Common Pitfalls
- Do not use graduated compression stockings alone - they are ineffective and cause skin damage 11
- Do not underdose in obesity - standard prophylactic doses may be inadequate 7
- Do not stop prophylaxis at discharge for high-risk patients - most VTE events occur post-discharge 8
- Do not use rivaroxaban routinely in medical patients - increased bleeding risk without clear benefit 1