Wells' Criteria for Pulmonary Embolism (PE) & DVT Calculator
Criteria
Result
Risk Stratification
| Score | Risk Category |
|---|---|
| Three-Tier Model | |
| 0 - 1 | Low Risk |
| 2 - 6 | Moderate Risk |
| >6 | High Risk |
| Two-Tier Model | |
| ≤4 | PE Unlikely (with d-dimer) |
| ≥5 | PE Likely (with CTA) |
EVIDENCE APPRAISAL for Wells' Criteria
The original Wells study for assessing Pulmonary Embolism (PE) was performed on cohorts where prevalence of PE was high: approximately 30%. Two further emergency department studies validated this tool with a 9.5%-12% PE prevalence.
The largest study demonstrated risk stratification with the Wells' Criteria:
- Low score of 0-1 having a 1.3% prevalence.
- Moderate score of 2-6 having a 16.2% prevalence.
- High score of >6 having a 37.5% prevalence.
The Christopher study divided the Wells scoring system for PE into 2 categories:
- A score of 4 or less was defined as "PE unlikely" and tested with a d-dimer.
- A score of 5 or more was defined as "PE likely" and went straight to CTA
Overall Incidence of PE was 12.1% in the "unlikely" group vs. 37.1% in the "likely" group.
If dimer was negative no further testing was performed.
If dimer was positive the patient went to CTA.
20.4% of all patients who went to CTA had a diagnosis of PE.
In the "PE unlikely" group, those with a negative dimer and discharged to home had an incidence of missed PE on 3 month follow up of 0.5% .
LITERATURE
ORIGINAL/PRIMARY REFERENCE
Research Paper
Wells PS, Anderson DR, M. Rodger, I. Stiell, J. F. Dreyer, D. Barnes, M. Forgie, G. Kovacs, J. Ward, M. J. Kovacs. Excluding pulmonary embolism at the bedside without diagnostic imaging: management of patients with suspected pulmonary embolism presenting to the emergency department by using a simple clinical model and d-dimer. Ann Intern Med. 2001 Jul 17;135(2):98-107. PubMed PMID: 11453709.
VALIDATION
Research Paper
Wolf SJ, McCubbin TR, Feldhaus KM, Faragher JP, Adcock DM. Prospective validation of Wells Criteria in the evaluation of patients with suspected pulmonary embolism. Ann Emerg Med. 2004 Nov;44(5):503-10. PubMed PMID: 15520710.
OTHER REFERENCES
Research Paper
van Belle A, Buller HR, Huisman MV, et al. Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography. JAMA : the journal of the American Medical Association. Jan 11 2006;295(2):172-179.
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About the Creator
Dr. Phil Wells is a Professor of Medicine at the University of Ottawa.
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Content Contributors
Benjamin Slovis, MD