Pulmonary embolism tools
PERC and Wells address diagnosis (whether to test); PESI and sPESI address prognosis after PE is confirmed.
| Characteristic | PERC | Wells PE | PESI | sPESI |
|---|---|---|---|---|
| Clinical question | Can PE be excluded without D-dimer testing in a low-risk patient? | What is the pretest probability of pulmonary embolism? | What is the 30-day mortality risk of a patient with confirmed acute PE? | Is a patient with acute PE at low risk of 30-day mortality? |
| Outcome predicted | Exclusion of PE | Pretest probability of PE | All-cause mortality | All-cause mortality |
| Time horizon | Current episode (45-day follow-up in studies) | Current episode | 30 days | 30 days |
| Intended population | US emergency department patients evaluated for PE. | Inpatients and outpatients with suspected PE (Canadian derivation). | Patients with acute PE in Pennsylvania hospitals (derivation) with internal/external validation. | Spanish RIETE registry and multicentre cohort. |
| Evidence level | Strong evidence | Strong evidence | Strong evidence | Strong evidence |
| Validation | PROPER cluster-randomised non-inferiority trial: 3-month thromboembolic events 0.1% with the PERC strategy vs 0% with usual care (non-inferior). | — | — | Derivation cohort (Jiménez 2010): 30-day mortality 1.0% with sPESI 0 vs 10.9% with sPESI ≥ 1. |
| Discrimination | — | — | — | — |
| Calibration | — | — | — | — |
| Geographic applicability | — | — | — | — |
| Guideline status | Supported by the 2018 ACEP clinical policy on suspected PE; evaluated in the PROPER randomised trial. | Incorporated in the 2019 ESC acute PE guideline diagnostic algorithms. | Used for risk stratification in the 2019 ESC acute PE guideline. | Used alongside PESI in the 2019 ESC acute PE guideline. |
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Inputs required
Which variables each model uses. Models with more inputs are not automatically better — validation in your population matters most.
| Input | PERC | Wells PE | PESI | sPESI |
|---|---|---|---|---|
| Clinician pretest probability | ●used | –not used | –not used | –not used |
| Age ≥ 50 years | ●used | –not used | –not used | –not used |
| Heart rate ≥ 100 beats/min | ●used | –not used | –not used | –not used |
| Oxygen saturation < 95% on room air | ●used | –not used | –not used | –not used |
| Unilateral leg swelling | ●used | –not used | –not used | –not used |
| Haemoptysis | ●used | ●used | –not used | –not used |
| Surgery or trauma within 4 weeks (requiring hospitalisation) | ●used | –not used | –not used | –not used |
| Prior PE or DVT | ●used | –not used | –not used | –not used |
| Hormone use (oral contraceptives, hormone replacement or oestrogen) | ●used | –not used | –not used | –not used |
| Clinical signs and symptoms of DVT | –not used | ●used | –not used | –not used |
| PE is the most likely diagnosis (or equally likely) | –not used | ●used | –not used | –not used |
| Heart rate > 100 beats/min | –not used | ●used | –not used | –not used |
| Immobilisation ≥ 3 days or surgery in the previous 4 weeks | –not used | ●used | –not used | –not used |
| Previous, objectively diagnosed PE or DVT | –not used | ●used | –not used | –not used |
| Malignancy (treatment within 6 months or palliative) | –not used | ●used | –not used | –not used |
| Age | –not used | –not used | ●used | –not used |
| Sex | –not used | –not used | ●used | –not used |
| History of cancer | –not used | –not used | ●used | ●used |
| History of heart failure | –not used | –not used | ●used | –not used |
| History of chronic lung disease | –not used | –not used | ●used | –not used |
| Heart rate ≥ 110 beats/min | –not used | –not used | ●used | ●used |
| Systolic BP < 100 mmHg | –not used | –not used | ●used | ●used |
| Respiratory rate ≥ 30 breaths/min | –not used | –not used | ●used | –not used |
| Temperature < 36 °C | –not used | –not used | ●used | –not used |
| Altered mental status | –not used | –not used | ●used | –not used |
| Arterial oxyhaemoglobin saturation < 90% | –not used | –not used | ●used | –not used |
| Age > 80 years | –not used | –not used | –not used | ●used |
| Chronic cardiopulmonary disease (heart failure or chronic lung disease) | –not used | –not used | –not used | ●used |
| Oxyhaemoglobin saturation < 90% | –not used | –not used | –not used | ●used |
Comparison shows model characteristics only. Different models predict different outcomes in different populations, so their numerical results are not directly comparable.