PESI Score in Pulmonary Embolism Management
The PESI score is a critical risk stratification tool that should be routinely used to identify low-risk PE patients (PESI Class I/II or sPESI=0) who are candidates for outpatient management, as these patients have 30-day mortality rates of ≤1.6-3.6% and can be safely discharged with direct oral anticoagulants when exclusion criteria are absent. 1, 2
Why PESI Matters: Core Risk Stratification
The PESI score was derived and validated in 15,752 patients and stratifies PE patients into five risk classes (I-V) based on 30-day mortality risk 3. The score demonstrates excellent discriminatory power with area under the ROC curve of 0.77-0.87 3, 4. This validated tool directly determines whether a patient requires inpatient versus outpatient management, fundamentally altering the treatment pathway. 1, 5
Mortality Risk by PESI Class
- PESI Class I (very low risk): 30-day mortality ≤1.6%, with 0% mortality in some validation studies 3, 4
- PESI Class II (low risk): 30-day mortality 3.6%, with 1.0% mortality in European validation 3
- PESI Class III-V (higher risk): Mortality ranges from 11.1% to 17.9%, requiring inpatient management 4
No patients in PESI Class I or II suffered recurrent VTE or major bleeding during follow-up in the original derivation cohort 3.
Simplified PESI (sPESI): The Practical Alternative
The sPESI uses six binary variables (age >80, cancer, chronic cardiopulmonary disease, pulse ≥110, SBP <100, O2 sat <90%) and classifies patients with a score of 0 as low-risk. 3 The sPESI was shown to be non-inferior to the original PESI in predicting 30-day mortality, with low-risk patients having 1.0-1.1% mortality 3, 1. The sPESI is simpler to calculate at the bedside and identifies 30-7-36.2% of patients as low-risk 3.
Treatment Algorithm Based on PESI/sPESI
Low-Risk Patients (PESI I/II or sPESI=0)
These patients should be managed as outpatients with direct oral anticoagulants (apixaban or rivaroxaban preferred) when mandatory exclusion criteria are absent. 1, 2 The British Thoracic Society recommends this approach as Grade B evidence 3.
Mandatory exclusion criteria that override PESI low-risk status include: 1, 2
- Physiologic instability (HR >110, SBP <100, O2 sat <90%, severe pain requiring opiates)
- Active bleeding or recent major bleeding risk
- Severe renal impairment, severe liver disease, or severe thrombocytopenia
- Social factors (inability to return home, lack of telephone access, compliance concerns)
Intermediate-Risk Patients (PESI III or Higher with sPESI ≥1)
These patients require inpatient management with further stratification based on right ventricular dysfunction and cardiac biomarkers. 1 Treatment includes standard anticoagulation, close monitoring for clinical deterioration, and consideration of reperfusion therapy if hemodynamic decompensation occurs 1.
High-Risk Patients (Hemodynamically Unstable)
Patients with arterial hypotension or shock require inpatient management with strong consideration of thrombolysis 6.
Critical Nuances and Pitfalls
Do not rely solely on RV dilation on imaging to exclude patients from outpatient management. 1, 2 The American College of Emergency Physicians recommends measuring cardiac biomarkers (BNP/troponin) for additional risk stratification if RV dilation is present 1, 2.
The presence of right heart thrombi represents a critical exception where anatomic location significantly impacts prognosis, with mortality of 21% versus 11% without right heart thrombi. 1 Thrombolytic therapy is the only treatment independently associated with decreased mortality in this subset 1.
Concomitant DVT is an adverse prognostic factor independently associated with 30-day all-cause mortality (OR 1.9,95% CI 1.5-2.4). 1
Implementation Requirements
A robust pathway for follow-up and monitoring must exist before discharging low-risk patients. 3, 2 This includes access to prompt outpatient care if symptoms worsen, consultant or senior clinician review before discharge, and immediate access to anticoagulation medications 2, 5.
Do not discharge patients without same-day anticoagulation. 1, 2 Patients must have immediate access to anticoagulation medications before leaving the emergency department 2.
Evidence of Underutilization
Despite strong validation, a 2015 study found that PESI may not have widespread use in clinical practice 7. Among 315 PE patients, there was no significant difference in hospital stay between low-risk (7.11 days) and high-risk (7.28 days) groups, and only 9% of low-risk patients were discharged early 7. This represents a significant gap between evidence-based guidelines and actual practice, resulting in unnecessary hospitalizations for low-risk patients. 7