Pulmonary embolism assessment of clinical probability and risk scores: Difference between revisions
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The diagnosis of PE is based primarily on the clinical evaluation combined with diagnostic modalities such as spiral [[Pulmonary embolism CT|CT]], [[Pulmonary embolism ventilation/perfusion scan|V/Q scan]], use of the [[Pulmonary embolism laboratory tests#D-dimers|D-dimer]] and [[Pulmonary embolism echocardiography or ultrasound|lower extremity ultrasound]]. | The diagnosis of PE is based primarily on the clinical evaluation combined with diagnostic modalities such as spiral [[Pulmonary embolism CT|CT]], [[Pulmonary embolism ventilation/perfusion scan|V/Q scan]], use of the [[Pulmonary embolism laboratory tests#D-dimers|D-dimer]] and [[Pulmonary embolism echocardiography or ultrasound|lower extremity ultrasound]]. | ||
Although, clinical pretest probability has shown to be fairly accurate,<ref name="pmid2332918">{{cite journal |author= |title=Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). The PIOPED Investigators |journal=[[JAMA : the Journal of the American Medical Association]] |volume=263 |issue=20 |pages=2753–9 |year=1990 |pmid=2332918 |doi= |url= |accessdate=2012-04-26}}</ref> the lack of validation has led to the use of a combination of both clinical and diagnostic variables to predict the pretest probability | Although, the clinical pretest probability has shown to be fairly accurate,<ref name="pmid2332918">{{cite journal |author= |title=Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). The PIOPED Investigators |journal=[[JAMA : the Journal of the American Medical Association]] |volume=263 |issue=20 |pages=2753–9 |year=1990 |pmid=2332918 |doi= |url= |accessdate=2012-04-26}}</ref> the lack of validation has led to the use of a combination of both: clinical and diagnostic variables to predict the pretest probability that aids in the immediate management of high-risk patients. | ||
===High Pretest Probability=== | ===High Pretest Probability=== | ||
Revision as of 18:49, 26 April 2012
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Editor(s)-In-Chief: The APEX Trial Investigators, C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Synonyms and Keywords: PE
Overview
The diagnosis of pulmonary embolism is based on clinical evaluation in conjunction with imaging modalities. Despite their individual sensitivities and specificities, studies have demonstrated that a combination of both these variables may help to discriminate suspected patients depending on their risk of developing pulmonary embolism and offer immediate management which is life-saving.
Pretest Probability
The diagnosis of PE is based primarily on the clinical evaluation combined with diagnostic modalities such as spiral CT, V/Q scan, use of the D-dimer and lower extremity ultrasound.
Although, the clinical pretest probability has shown to be fairly accurate,[1] the lack of validation has led to the use of a combination of both: clinical and diagnostic variables to predict the pretest probability that aids in the immediate management of high-risk patients.
High Pretest Probability
Many authors, reserve the term high pretest probability for those patients with a clinical presentation consistent with PE, in whom an alternative diagnosis is not apparent (e.g. pneumonia) and who have known risk factors for venous thromboembolism (VTE).
Low Pretest Probability
Low pretest probability patients include those patients with an alternative diagnosis to explain the clinical findings or those without risk factors.
Intermediate Pretest Probability
Intermediate probability patients include those patients not fitting either high or low pretest probability definitions.
Supportive trial data
- The Prospective Investigation On Pulmonary Embolism Diagnosis (PIOPED) investigators demonstrated that all patients with or without pulmonary embolism had abnormal V/Q scans of high, intermediate, or low probability (sensitivity, 98%; specificity, 10%). Furthermore, of the 116 patients with high-probability scans and definitive angiograms, only 88% had pulmonary embolism. On the contrary, only a minority of patients with pulmonary embolism demonstrated high-probability scans (sensitivity, 41%; specificity, 97%). Similarly, of the 322 patients with intermediate-probability scans and definitive angiograms, only 33% had pulmonary embolism. Despite these contrast findings, classification of patients based on clinical probability was fairly accurate and that with increasing clinical probability, an increase in PE prevalence was also observed. However, majority of these patients demonstrated low to moderate clinical probability which required no further intervention.[1]
- Another prospective multicentre outcome study by Musset et al, demonstrated that with-holding anticoagulation in patients with low or intermediate clinical probability and negative spiral CT and ultrasonagraphy was safe. Of the 1041 patients enrolled in the study, 525 were assessed as having low or intermediate clinical probability and 507 were not treated with anticoagulation. During a 3-month follow-up, only 9 patients experienced venous thromboembolism (1.8% [0.8-3.3]) and the diagnostic strategy proved inconclusive in 95 (9.1%) patients.[2]
Predicting the Risk of Pulmonary Embolism
The decision to do medical imaging is usually based on clinical grounds, i.e. the medical history, symptoms and findings on physical examination.
- Development of the Wells score
The most commonly used method to predict clinical probability is the Wells score, a clinical prediction rule, the use of which is complicated by multiple versions being available.
- In 1995, based on literature search and clinical criteria, Wells et al developed a prediction rule to predict the likelihood of PE .[3]
- The prediction rule was revised in 1998.[4] This prediction rule was further revised and simplified during a validation by Wells et al in 2000.[5]
- In the 2000 publication, Wells proposed two different scoring systems using cutoffs of 2 or 4 with the same prediction rule. In 2001, Wells published results using the more conservative cutoff of 2, to create three categories.[6]
- An additional version, the "modified extended version", using the more recent cutoff of 2 but including findings from Wells's initial studies were proposed.[7]
- Most recently, a further study reverted to Wells's earlier use of a cutoff of 4 points to create only two categories.[8]
There are additional prediction rules for PE, such as the Geneva rule. More importantly, the use of any rule is associated with reduction in recurrent thromboembolism.[9]
Wells score
The Wells score:[10]
- Clinically suspected DVT (leg swelling, pain with palpation) - 3.0 points
- Alternative diagnosis is less likely than PE - 3.0 points
- Tachycardia - 1.5 points
- Immobilization/surgery in previous four weeks - 1.5 points
- History of DVT or PE - 1.5 points
- Hemoptysis - 1.0 points
- Malignancy (treatment for within 6 months, palliative) - 1.0 points
- Interpretation of the Wells score
Traditional interpretation (Wells criteria) [5][6]
- Score >6.0 - High (probability 59% based on pooled data[11])
- Score 2.0 to 6.0 - Moderate (probability 29% based on pooled data[11])
- Score <2.0 - Low (probability 15% based on pooled data[11])
Alternate interpretation (Modified Wells criteria) [5][8]
- Score > 4 - PE likely. Consider diagnostic imaging.
- Score 4 or less - PE unlikely. Consider D-dimer to rule out PE.
References
- ↑ 1.0 1.1 "Value of the ventilation/perfusion scan in acute pulmonary embolism. Results of the prospective investigation of pulmonary embolism diagnosis (PIOPED). The PIOPED Investigators". JAMA : the Journal of the American Medical Association. 263 (20): 2753–9. 1990. PMID 2332918.
|access-date=requires|url=(help) - ↑ Musset D, Parent F, Meyer G, Maître S, Girard P, Leroyer C, Revel MP, Carette MF, Laurent M, Charbonnier B, Laurent F, Mal H, Nonent M, Lancar R, Grenier P, Simonneau G (2002). "Diagnostic strategy for patients with suspected pulmonary embolism: a prospective multicentre outcome study". Lancet. 360 (9349): 1914–20. doi:10.1016/S0140-6736(02)11914-3. PMID 12493257. Retrieved 2012-04-26. Unknown parameter
|month=ignored (help) - ↑ Wells PS, Hirsh J, Anderson DR, Lensing AW, Foster G, Kearon C, Weitz J, D'Ovidio R, Cogo A, Prandoni P (1995). "Accuracy of clinical assessment of deep-vein thrombosis". Lancet. 345 (8961): 1326–30. doi:doi:10.1016/S0140-6736(95)92535-X Check
|doi=value (help). PMID 7752753. - ↑ Wells PS, Ginsberg JS, Anderson DR, Kearon C, Gent M, Turpie AG, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J (1998). "Use of a clinical model for safe management of patients with suspected pulmonary embolism". Ann Intern Med. 129 (12): 997–1005. PMID 9867786.
- ↑ 5.0 5.1 5.2 Wells P, Anderson D, Rodger M, Ginsberg J, Kearon C, Gent M, Turpie A, Bormanis J, Weitz J, Chamberlain M, Bowie D, Barnes D, Hirsh J (2000). "Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer". Thromb Haemost. 83 (3): 416–20. PMID 10744147.
- ↑ 6.0 6.1 Wells PS, Anderson DR, Rodger M, Stiell I, Dreyer JF, Barnes D, Forgie M, Kovacs G, Ward J, Kovacs MJ (2001). "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. 135 (2): 98–107. PMID 11453709.
- ↑ Sanson BJ, Lijmer JG, Mac Gillavry MR, Turkstra F, Prins MH, Büller HR (2000). "Comparison of a clinical probability estimate and two clinical models in patients with suspected pulmonary embolism. ANTELOPE-Study Group". Thromb. Haemost. 83 (2): 199–203. PMID 10739372.
- ↑ 8.0 8.1 van Belle A, Büller H, Huisman M, Huisman P, Kaasjager K, Kamphuisen P, Kramer M, Kruip M, Kwakkel-van Erp J, Leebeek F, Nijkeuter M, Prins M, Sohne M, Tick L (2006). "Effectiveness of managing suspected pulmonary embolism using an algorithm combining clinical probability, D-dimer testing, and computed tomography". JAMA. 295 (2): 172–9. doi:10.1001/jama.295.2.172. PMID 16403929.
- ↑ Roy PM, Meyer G, Vielle B, Le Gall C, Verschuren F, Carpentier F, Leveau P, Furber A (2006). "Appropriateness of diagnostic management and outcomes of suspected pulmonary embolism". Ann. Intern. Med. 144 (3): 157–64. PMID 16461959.
- ↑ Neff MJ (2003). "ACEP releases clinical policy on evaluation and management of pulmonary embolism". American family physician. 68 (4): 759–60. PMID 12952389.
- ↑ 11.0 11.1 11.2 Stein PD, Woodard PK, Weg JG, Wakefield TW, Tapson VF, Sostman HD, Sos TA, Quinn DA, Leeper KV, Hull RD, Hales CA, Gottschalk A, Goodman LR, Fowler SE, Buckley JD (2007). "Diagnostic pathways in acute pulmonary embolism: recommendations of the PIOPED II Investigators". Radiology. 242 (1): 15–21. doi:10.1148/radiol.2421060971. PMID 17185658.