What is the PESI Score?
The Pulmonary Embolism Severity Index (PESI) is a validated clinical prognostic tool that stratifies patients with acute pulmonary embolism into five risk classes (I-V) based on 11 clinical variables to predict 30-day mortality and guide decisions about outpatient versus inpatient management. 1
Purpose and Clinical Application
The PESI score was derived and validated using a cohort of 15,752 patients with confirmed PE to identify independent predictors of 30-day mortality. 1 The primary clinical utility is identifying low-risk patients (PESI class I and II) who are safe candidates for outpatient management, with these patients having 30-day mortality rates of ≤1.6% and 3.6%, respectively. 1
Risk Classification
The PESI stratifies patients into five classes with progressively increasing mortality risk:
- Class I (very low risk): 30-day mortality ≤1.6% 1
- Class II (low risk): 30-day mortality 3.6% 1
- Classes III-V (higher risk): Progressively higher mortality requiring inpatient management 2
Patients in PESI class I or II had no recurrent VTE or major bleeding during follow-up in the original validation study. 1
Performance Characteristics
The PESI demonstrates excellent discriminatory power with:
- Area under the ROC curve of 0.77 (95% CI 0.75-0.79) in internal validation 1
- AUC of 0.87 in external European validation for 90-day mortality 1
- Superior discriminatory ability compared to the Geneva score (AUC 0.76 vs 0.61) 1
External validation confirmed 0% to 1.0% mortality in PESI class I and II patients at 90 days, with no major bleeding or recurrent VTE. 1
Simplified PESI (sPESI)
A simplified version exists using only six binary variables (each worth 1 point):
- Age >80 years
- Active cancer
- Chronic cardiopulmonary disease
- Pulse ≥110 bpm
- Systolic blood pressure <100 mm Hg
- Arterial oxygen saturation <90% 1
A score of zero classifies patients as low risk, with 30-day mortality of 1.0-1.1%. 1 The sPESI was shown to be non-inferior to the original PESI in predicting 30-day mortality, though it classified fewer patients as low risk (30.7-36.2% vs 36.3% with PESI). 1
Clinical Decision-Making Algorithm
The British Thoracic Society recommends that all patients with PE should be assessed for suitability for outpatient management using PESI or sPESI (Grade B recommendation). 1
The management pathway based on PESI:
- PESI Class I-II or sPESI = 0: Consider outpatient management if no clinical exclusion criteria exist 2
- PESI Class III or higher: Consider inpatient management 2
- Hemodynamically unstable (regardless of PESI): Requires inpatient management with consideration of thrombolysis 2
Patients assessed as low risk and suitable for outpatient management should be offered treatment in an outpatient setting where a robust pathway exists for follow-up and monitoring (Grade B recommendation). 1
Important Caveats
The original PESI classified a significantly greater proportion of patients as low-risk compared to sPESI (40.9% vs 36.8%), and had greater discriminatory power (AUC 0.78 vs 0.72). 3 This means the original PESI may safely identify more patients eligible for outpatient management.
PESI performs better than the Geneva score at identifying low-risk patients, with PESI class I-II having 0.9% mortality versus 5.6% mortality in Geneva low-risk patients. 1
The PESI also accurately predicts long-term mortality, maintaining discriminatory power at 6 months (AUC 0.77) and 12 months (AUC 0.79). 4
Clinical Exclusion Criteria
Even with low PESI scores, patients should not be discharged if they have:
- Need for thrombolysis or inotropic support
- Severe hypoxemia or hypotension requiring intervention
- Pain requiring parenteral analgesia
- Active bleeding or high bleeding risk
- Poor compliance anticipated
- Lack of adequate social support or follow-up 1
All patients considered for outpatient management must be reviewed by a consultant or appropriate senior clinician before discharge. 2