Scoring Tools for DVT Prophylaxis
The two primary validated scoring tools for DVT prophylaxis risk stratification are the Padua Prediction Score and the IMPROVE VTE Risk Assessment Model, both of which should be used to assess thromboembolism risk prior to initiating prophylaxis in hospitalized medical patients. 1
Primary Risk Assessment Tools
Padua Prediction Score
The Padua score is a validated tool that stratifies VTE risk in hospitalized medical patients using the following criteria 1:
- Active cancer (metastatic or receiving chemotherapy): 3 points
- Previous VTE (excluding superficial thrombophlebitis): 3 points
- Reduced mobility (bed rest with bathroom privileges ≥3 days): 3 points
- Known thrombophilic condition: 3 points
- Recent trauma and/or surgery (<1 month): 2 points
- Elderly age (>70 years): 1 point
- Heart and/or respiratory failure: 1 point
- Acute myocardial infarction or ischemic stroke: 1 point
- Ongoing hormonal treatment: 1 point
- Obesity (BMI >30): 1 point
- Acute infection and/or rheumatologic disorder: 1 point
Risk stratification interpretation: A Padua score of 0-3 indicates low risk (VTE incidence 0.3%), while a score ≥4 indicates high risk (VTE incidence 11% without prophylaxis, reduced to 2.2% with prophylaxis, HR 0.13). 1
IMPROVE VTE Risk Assessment Model
The IMPROVE VTE score provides an alternative validated approach 1:
- Previous VTE: 3 points
- Known thrombophilia (congenital or acquired): 2 points
- Lower limb paralysis (leg falls to bed by 5 seconds but has some effort against gravity): 2 points
- Active cancer: 2 points
- Immobilization >7 days: 1 point
- ICU/CCU stay: 1 point
- Age >60 years: 1 point
Risk stratification interpretation: Score 0-1 = low risk (0.5% VTE rate), score 2-3 = moderate risk (1.5% VTE rate), score ≥4 = high risk (5.7% VTE rate). A score ≥2 indicates need for VTE prophylaxis. 1
Bleeding Risk Assessment Tool
IMPROVE Bleeding Risk Assessment Model
This complementary tool assesses bleeding risk to balance prophylaxis decisions 1:
- Platelet count <50 × 10⁹/L: 4 points
- Bleeding in 3 months before admission: 4 points
- Active gastroduodenal ulcer: 4.5 points
- Age >85 years: 3.5 points
- Hepatic failure (INR >1.5): 2.5 points
- Renal failure (GFR <30 mL/min per m²): 2.5 points
- ICU/Critical Care Unit stay: 2.5 points
- Central venous catheter: 2 points
- Rheumatic disease: 2 points
- Current cancer: 2 points
- Age 40-80 years: 1.5 points
- Renal failure (GFR 30-59 mL/min per m²): 1 point
- Male sex: 1 point
Bleeding risk interpretation: Score <7 indicates low bleeding risk (0.4% major bleeding/1.5% any bleeding), while score ≥7 indicates high bleeding risk (4.1% major bleeding/7.9% any bleeding). 1
Clinical Application Algorithm
Step 1: Calculate Padua score or IMPROVE VTE score for all hospitalized medical patients 1
Step 2: If Padua score ≥4 or IMPROVE VTE score ≥2, calculate IMPROVE bleeding score 1
Step 3: Make prophylaxis decision based on combined assessment 1:
- High VTE risk + low bleeding risk (IMPROVE bleeding <7): Initiate pharmacologic prophylaxis with LMWH or UFH
- High VTE risk + high bleeding risk (IMPROVE bleeding ≥7): Use mechanical prophylaxis (IPC devices) instead of pharmacologic methods 2
- Low VTE risk: Early ambulation alone is sufficient 2
Common Pitfalls to Avoid
Do not apply universal VTE prophylaxis without risk assessment, as the American College of Physicians explicitly does not support performance measures promoting universal prophylaxis regardless of risk. 1
Do not use graduated compression stockings as primary prophylaxis, as the American College of Physicians strongly recommends against their use for VTE prevention in medical patients. 1
Do not overlook bleeding risk assessment, as pharmacologic prophylaxis increases bleeding events (RR 1.34, absolute increase 9 events per 1000 persons) despite reducing PE (RR 0.69, absolute reduction 4 events per 1000 persons). 1