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Wells score (pulmonary embolism)

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The Wells score is a clinical prediction rule used to classify patients suspected of having pulmonary embolism (PE) into risk groups by quantifying the pre-test probability. It is different than Wells score for DVT (deep vein thrombosis). It was originally described by Wells et al. in 1998,[1] using their experience from creating Wells score for DVT in 1995.[2] Today, there are multiple (revised or simplified) versions of the rule, which may lead to ambiguity.[1][3][4]

The purpose of the rule is to select the best method of investigation (e.g. D-dimer testing, CT angiography) for ruling in or ruling out the diagnosis of PE, and to improve the interpretation and accuracy of subsequent testing, based on a Bayesian framework for the probability of the diagnosis.

The rule is more objective than clinician gestalt, but still includes subjective opinion (unlike e.g. Geneva score).

Original algorithm[1]

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Originally it was developed in 1998 to improve the low specificity of V/Q scan results (which then had a more important role in the workup of PE than now).

It categorized patients into 3 categories: low / moderate / high probability. It was formulated in the form of an algorithm, not a score.

Subsequent testing choices were V/Q scanning, pulmonary angiography, and serial compression ultrasound.

Revised score [3][4]

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The emergence of D-dimer assays prompted the revision of the rule.

This version was published as a score, and according to the final score, patients could be categorized in either 3 groups (low / intermediate / high risk) or 2 groups (low / high risk)

Subsequent testing choices included D-dimer testing for low risk cases, and V/Q scanning, pulmonary angiography, and compression ultrasonography for intermediate / high risk patients and low-risk patients with positive D-dimer results.

Wells score for PE [3]
Variable Points
Clinical signs and symptoms of DVT 3
An alternate diagnosis is less likely than PE 3
Heart rate >100 1.5
Immobilization or surgery in the previous 4 weeks 1.5
Previous DVT / PE 1.5
Hemoptysis 1
Malignancy (treatment currently, in the previous 6 months, or palliative) 1

Risk of PE using 3 categories (data from the derivation group)

Risk group Points required Risk of PE
Low risk 0-1 3.6%
Moderate risk 2-6 20.5%
High risk >6 66.7%

Risk of PE using 2 categories (data from the derivation group)

Risk group Points required Risk of PE
Low 0-4 5.1%
High >4 39.1%

References

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  1. ^ a b c Wells, Philip S.; Ginsberg, Jeffrey S.; Anderson, David R.; Kearon, Clive; Gent, Michael; Turpie, Alexander G.; Bormanis, Janis; Weitz, Jeffrey; Chamberlain, Michael; Bowie, Dennis; Barnes, David; Hirsh, Jack (1998-12-15). "Use of a Clinical Model for Safe Management of Patients with Suspected Pulmonary Embolism". Annals of Internal Medicine. 129 (12): 997–1005. doi:10.7326/0003-4819-129-12-199812150-00002. ISSN 0003-4819. PMID 9867786. S2CID 41389736.
  2. ^ Wells, P. S.; Hirsh, J.; Anderson, D. R.; Lensing, A. W.; Foster, G.; Kearon, C.; Weitz, J.; D'Ovidio, R.; Cogo, A.; Prandoni, P. (1995-05-27). "Accuracy of clinical assessment of deep-vein thrombosis". Lancet. 345 (8961): 1326–1330. doi:10.1016/s0140-6736(95)92535-x. ISSN 0140-6736. PMID 7752753. S2CID 23107192.
  3. ^ a b c Wells, P. S.; Anderson, D. R.; Rodger, M.; Ginsberg, J. S.; Kearon, C.; Gent, M.; Turpie, A. G.; Bormanis, J.; Weitz, J.; Chamberlain, M.; Bowie, D.; Barnes, D.; Hirsh, J. (March 2000). "Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer". Thrombosis and Haemostasis. 83 (3): 416–420. doi:10.1055/s-0037-1613830. ISSN 0340-6245. PMID 10744147. S2CID 10013631.
  4. ^ a b Wells, Philip S.; Anderson, David R.; Rodger, Marc; Stiell, Ian; Dreyer, Jonathan F.; Barnes, David; Forgie, Melissa; Kovacs, George; Ward, John; Kovacs, Michael J. (2001-07-17). "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". Annals of Internal Medicine. 135 (2): 98–107. doi:10.7326/0003-4819-135-2-200107170-00010. ISSN 0003-4819. PMID 11453709. S2CID 2708155.