Wells' Criteria for Pulmonary Embolism
The Wells’ Criteria risk stratifies patients for pulmonary embolism (PE) and provides an estimated pre-test probability. The physician can then chose what further testing is required for diagnosing pulmonary embolism (I.E. d-dimer or CT angiogram).
The Wells’ Criteria risk stratifies patients for pulmonary embolism (PE), and has been validated in both inpatient and emergency department settings. Its score is often used in conjunction with d-dimer testing to evaluate for PE.
- There must first be a clinical suspicion for PE in the patient (this should not be applied to all patients with chest pain or shortness of breath, for example).
- Wells' can be used with either 3 tiers (low, moderate, high) or 2 tiers (unlikely, likely). We recommend the two tier model as this is supported by ACEP’s 2011 clinical policy on PE. (See Next Steps)
- Wells’ is often criticized for having a “subjective” criterion in it (“PE #1 diagnosis or equally likely”)
- Wells’ is not meant to diagnose PE but to guide workup by predicting pre-test probability of PE and appropriate testing to rule out the diagnosis.
- The Wells’ Score has been validated multiple times in multiple clinical settings.
- Physicians have a low threshold to test for pulmonary embolism.
- The score is simple to use and provides clear cutoffs for the predicted probability of pulmonary embolism.
- The score aids in potentially reducing the number of CTAs performed on low-risk PE patients.
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From the Creator
Dr. Wells on use of his scores for MDCalc:
The model should be applied only after a history and physical suggests that venous thromboembolism is a diagnostic possibility. it should not be applied to all patients with chest pain or dyspnea or to all patients with leg pain or swelling. This is the most common mistake made. Also, never never do the D-dimer first [before history and physical exam]. The monster in the box is that the D-dimer is done first and is positive (as it is for many patients with non-VTE conditions) and then the physician assumes that VTE is now possible and then the model is done. Do the history and physical exam first and decide if VTE is a diagnostic possibility!
Dr. Wells on testing in medicine for MDCalc:
The importance of Clinical pretest probability is underutilized in medicine. Recognizing the power of a simple concept, derived essentially from Bayes theorem, that discordance between the clinical PTP and the test result should raise suspicion of a false negative test (if high PTP) or false positive test (if low PTP), we sought to derive prediction rules for suspected DVT and for suspected PE. Used appropriately these rules will improve patient care.
About the Creator
Phil Wells, MD, MSc, is a professor and chief of the Department of Medicine at The University of Ottawa. He is also on the faculty of medicine and a senior scientist at the Ottawa Hospital Research Institute. Dr. Wells researches thromboembolism, thrombophilia and long term bleeding risk in patients on anticoagulants.
To view Dr. Phil Wells's publications, visit PubMed