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PESI (Pulmonary Embolism Severity Index) Score

Predicts 30-day mortality in acute pulmonary embolism and stratifies patients for safe outpatient treatment

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Why use it

Acute PE has a 30-day mortality of 1–10% overall, but clinical severity varies enormously — from hemodynamically stable ambulatory patients to those in cardiogenic shock. The PESI enables safe identification of low-risk patients (Class I–II) who can be managed as outpatients or with early discharge, avoiding unnecessary hospitalization and its associated complications (nosocomial infection, DVT, cost). Multiple randomized controlled trials (Outpatient Treatment of Pulmonary Embolism — OTPE trial, HOME-PE trial) have validated that PESI Class I–II patients can be safely treated at home with direct oral anticoagulants (DOACs) with non-inferior outcomes to inpatient management. The ESC 2019 guidelines recommend PESI or sPESI as the first step in PE risk stratification.

About

The Pulmonary Embolism Severity Index (PESI) was developed by Aujesky and colleagues from the University of Pittsburgh and published in the American Journal of Respiratory and Critical Care Medicine in 2005. It was derived from a retrospective cohort of 10,354 patients with acute symptomatic pulmonary embolism (PE) and validated in a separate prospective multicenter cohort. The PESI uses 11 clinical variables — age, sex, presence of cancer, heart failure, chronic lung disease, and five physiological parameters (heart rate, systolic blood pressure, respiratory rate, temperature, mental status, and oxygen saturation) — to predict 30-day all-cause mortality, enabling risk stratification into five classes (I–V) with escalating mortality risk. Class I and II patients (PESI ≤85) have low 30-day mortality (0–3.5%), while Class V patients (PESI >125) have 10–24.5% mortality. The PESI has been prospectively validated in multiple international cohorts and incorporated into the European Society of Cardiology (ESC) 2019 PE guidelines and the American College of Chest Physicians (CHEST) guidelines as a tool for identifying low-risk patients suitable for outpatient treatment or early discharge. The simplified PESI (sPESI), developed by Jiménez and colleagues in 2010, uses 6 binary variables and has comparable prognostic accuracy with greater ease of use.

When to use

  • Acute symptomatic pulmonary embolism confirmed on CT pulmonary angiography (CTPA) or V/Q scan
  • Deciding between inpatient versus outpatient management of acute PE
  • Early discharge planning in patients admitted for PE
  • Risk stratification to guide intensity of monitoring and choice of anticoagulation
  • Identifying patients who do NOT require ICU admission (low PESI ± normal RV function on echocardiography)
  • NOT for use in massive PE with hemodynamic compromise — these patients require immediate reperfusion therapy (systemic thrombolysis or catheter-directed therapy) regardless of PESI

Formula

PESI = Age in years + 10 if male sex + 30 if cancer + 10 if heart failure + 10 if chronic lung disease + 20 if HR ≥ 110 bpm + 30 if SBP < 100 mmHg + 20 if RR ≥ 30 breaths/min + 20 if temperature < 36°C + 60 if altered mental status + 20 if SpO2 < 90% Risk Classes: Class I: ≤ 65 0–1.6% 30-day mortality (Very Low) Class II: 66–85 1.7–3.5% (Low) Class III: 86–105 3.2–7.1% (Moderate) Class IV: 106–125 4.0–11.4% (High) Class V: > 125 10.0–24.5% (Very High) Simplified PESI (sPESI): Age > 80 + cancer + chronic cardiopulmonary disease + HR ≥ 110 + SBP < 100 + SpO2 < 90% (each = 1 pt) sPESI 0 = low risk; sPESI ≥ 1 = high risk

Pearls & pitfalls

  • PESI Class I + normal troponin + normal RV on echo is the combination supported by RCTs (OTPE trial) for safe outpatient PE treatment — class alone is not sufficient without confirming absence of right heart strain.
  • The simplified PESI (sPESI) is equally validated and easier to apply at the bedside: age >80 (+1), cancer (+1), chronic cardiopulmonary disease (+1), HR ≥110 (+1), SBP <100 (+1), SpO2 <90% (+1). Score 0 = low risk; ≥1 = high risk.
  • PESI does NOT apply to MASSIVE PE (hemodynamic instability: SBP <90 mmHg, or drop ≥40 mmHg × 15 min not explained by other cause) — these patients are immediately high risk regardless of PESI score.
  • Male sex adds +10 points — this reflects the higher observed mortality in men with PE in the derivation cohort. This does not mean men cannot be low-risk; many male patients are still Class I–II.
  • The PESI includes age directly as the starting point — a 70-year-old without comorbidities starts at PESI 70 (Class II), which means almost no elderly patients will be Class I.
  • Troponin I or T elevation and NT-proBNP/BNP elevation are markers of RV strain that independently predict adverse outcomes — low-risk PESI patients with elevated biomarkers may still benefit from hospitalization (intermediate-low risk per ESC 2019).
  • Cancer is a major contributor to PESI (adds 30 points) — most cancer patients will be Class III+ regardless of clinical stability. Consider cancer-associated VTE management guidelines (LMWH or DOAC depending on cancer type).
  • sPESI 0 has a 30-day mortality of 1.0% (95% CI 0.6–1.6%) and has been validated in the HOME-PE RCT (Couturaud 2022) for home treatment selection.
  • PE recurrence risk is not captured by PESI — provoked vs. unprovoked PE status determines anticoagulation duration (provoked: 3 months; unprovoked: extended duration).

Next steps

PESI Class I (≤65) or Class II (66–85): Low risk — 30-day mortality 0–3.5%. Consider outpatient management if: (1) no significant comorbidities requiring hospitalization; (2) no contraindication to anticoagulation; (3) reliable medication adherence and access; (4) normal RV function on echocardiography or normal BNP/troponin; (5) stable O2 saturation on room air; (6) safe home environment and follow-up. Initiate DOAC (rivaroxaban or apixaban preferred). PESI Class III (86–105): Moderate risk — 3.2–7.1% mortality. Hospital admission for monitoring. DOAC or heparin bridge to warfarin. Echocardiography for RV assessment. Serial troponin and BNP. PESI Class IV–V (106–125, >125): High risk — 4–24.5% mortality. ICU or high-dependency unit admission. Continuous cardiac monitoring. Assess for hemodynamic instability. Echocardiography urgently. Consider systemic thrombolysis (tPA 100 mg over 2h) if massive PE with shock. Catheter-directed therapy or surgical embolectomy for selected patients.

Evidence

Aujesky D et al. Derivation and validation of a prognostic model for pulmonary embolism. Am J Respir Crit Care Med. 2005;172(8):1041-1046. PMID:16020800. Derivation: n=10,354; validation: n=15,531. C-statistic 0.78. Jiménez D et al. Simplification of the pulmonary embolism severity index for prognostication. Arch Intern Med. 2010;170(15):1383-1389 (sPESI). Aujesky D et al. Outpatient versus inpatient treatment for patients with acute pulmonary embolism: an international, open-label, randomised, non-inferiority trial (OTPE). Lancet. 2011;378(9785):41-48. PMID:21703676. Couturaud F et al. HOME-PE trial. NEJM 2022. ESC 2019 PE Guidelines.

References

  1. Aujesky D et al. Derivation and validation of a prognostic model for pulmonary embolism. Am J Respir Crit Care Med. 2005;172(8):1041-1046. — link
  2. Jiménez D et al. Simplification of the pulmonary embolism severity index for prognostication in patients with acute symptomatic pulmonary embolism. Arch Intern Med. 2010;170(15):1383-1389. — link
  3. Aujesky D et al. Outpatient versus inpatient treatment for patients with acute pulmonary embolism: an international, open-label, randomised, non-inferiority trial (OTPE). Lancet. 2011;378(9785):41-48. — link
  4. Konstantinides SV et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism. Eur Heart J. 2020;41(4):543-603. — link
  5. Couturaud F et al. Effect of a Diagnostic Strategy Using an Abbreviated Out-of-Hospital Initiation of Anticoagulation for Pulmonary Embolism (HOME-PE) on 3-Month Outcomes. JAMA. 2022. — link