What are risk calculators for Pulmonary Embolism (PE)?

Risk Calculators for Pulmonary Embolism (PE)

The most validated and widely used risk calculators for PE are the Wells score, Geneva score, PESI (Pulmonary Embolism Severity Index), and Kline criteria, which help determine both the pretest probability of PE diagnosis and risk stratification for mortality. 1

Diagnostic Risk Calculators

Wells Score

• Most widely validated diagnostic prediction rule
• Components:
  • Clinical signs of DVT (3 points)
  • Alternative diagnosis less likely than PE (3 points)
  • Heart rate >100 bpm (1.5 points)
  • Immobilization/surgery in previous 4 weeks (1.5 points)
  • Previous DVT/PE (1.5 points)
  • Hemoptysis (1 point)
  • Malignancy (1 point)
• Interpretation:
  • Traditional: Low (<2), Intermediate (2-6), High (>6)
  • Dichotomized: PE Unlikely (≤4), PE Likely (>4)

Geneva Score

• Developed in Europe, objective criteria without clinical judgment
• Components:
  • Age >65 years (1 point)
  • Previous DVT or PE (3 points)
  • Surgery or fracture within 1 month (2 points)
  • Active malignancy (2 points)
  • Unilateral lower limb pain (3 points)
  • Hemoptysis (2 points)
  • Heart rate 75-94 bpm (3 points) or ≥95 bpm (5 points)
  • Pain on deep vein palpation and unilateral edema (4 points)
• Interpretation: Low (0-3), Intermediate (4-10), High (≥11)

Kline Criteria

• Specifically designed to identify patients safe for D-dimer testing
• "Unsafe" for D-dimer testing if:
  • Shock index (heart rate/systolic BP) >1.0 OR age >50 years
  • PLUS any one of: unexplained hypoxemia (SaO₂ <95%), unilateral leg swelling, recent major surgery, or hemoptysis
• PE prevalence: 42.1% in "unsafe" patients vs. 13.3% in "safe" patients 1

Pregnancy-Adapted Geneva (PAG) Score

• Specifically for pregnant women
• Superior discriminative power compared to standard scoring systems (AUC 0.795)
• Components similar to Geneva score but adapted for pregnancy
• Categorizes patients into low (2.3% PE prevalence), intermediate (11.6% PE prevalence), and high risk (61.5% PE prevalence) 2

Prognostic Risk Calculators

PESI (Pulmonary Embolism Severity Index)

• Gold standard for risk stratification after PE diagnosis
• 11 variables including age, gender, comorbidities, vital signs
• Class I-II: Low risk (≤85 points) - consider outpatient management
• Class III-V: Higher risk (>85 points) - consider inpatient management

Simplified PESI (sPESI)

• Streamlined version of PESI
• One point each for: age >80, cancer, chronic cardiopulmonary disease, heart rate >110 bpm, systolic BP <100 mmHg, O₂ saturation <90%
• 0 points: Low risk (30-day mortality ~1%)
• ≥1 point: Higher risk (30-day mortality ~10%)

PERFORM Score

• Newer, simplified tool for CTPA-confirmed PE patients
• Based only on age, heart rate, and PaO₂
• Score range: 0-12
• Low risk (<5): Shorter recovery time
• High risk (≥5): Higher 30-day mortality
• Comparable predictive performance to PESI and sPESI 3

Hestia Criteria

• Determines eligibility for outpatient PE treatment
• Consists of 11 clinical parameters
• Any positive criterion suggests inpatient treatment is needed

Implementation Considerations

Clinical Application Algorithm

1. Use Wells or Geneva score to assess PE probability
2. For low/intermediate probability:
   • Apply D-dimer testing (except in pregnant women where D-dimer has poor specificity) 2
   • If D-dimer negative and low probability, PE can be excluded
3. For high probability or positive D-dimer:
   • Proceed to imaging (CTPA or V/Q scan)
4. After PE diagnosis:
   • Apply PESI/sPESI to determine mortality risk and guide disposition

Common Pitfalls

• Clinical prediction rules are often underutilized in practice (calculated in only 0.6% of suspected PE cases in one study) 4
• D-dimer testing is frequently ordered inappropriately in high-risk patients where imaging should be performed directly 1
• Risk calculators should guide but not replace clinical judgment, especially in unstable patients 2
• Cancer patients may require different approaches as Wells criteria and D-dimer testing are less predictive in this population 1

Special Populations

• For pregnant women: Use the Pregnancy-Adapted Geneva Score rather than standard scores 2
• For cancer patients: Consider cancer-specific prognostic scores like POMPE-C or EPIPHANY index 1
• For elderly patients: Consider age-adjusted D-dimer thresholds (age × 10 ng/mL for patients >50 years) 5

By systematically applying these validated risk calculators, clinicians can more accurately diagnose PE and appropriately triage patients based on their mortality risk, ultimately improving patient outcomes.