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Clinical probability scoring and pulmonary embolism

Three Part Question

In [a patient presenting with features suggestive of pulmonary embolus] what is [the diagnostic utility of clinical assessment] in [stratifying risk of pulmonary embolus]?

Clinical Scenario

A 30 year old man presents to the emergency department with a spontaneous onset of atraumatic pleuritic chest pain. He has no previous medical history and has no shortness of breath or haemodynamic compromise. You wonder whether his clinical features and risk factors can help to safely exclude a pulmonary embolus.

Search Strategy

Medline 1966-06/03 using the OVID interface.
(exp Pulmonary Embolism OR exp THROMBOEMBOLISM OR PE.mp OR pulmonary infarct$.mp OR Pulmonary Embol$.mp) AND (exp Risk Assessment OR risk assessment.mp OR risk stratification.mp OR probability.mp) LIMIT to human AND English language

Search Outcome

938 papers were found of which 935 papers were irrelevant to the question, of insufficient quality or did not report a mathematically derived scoring systems. The remaining 4 are included in the table below. N.B. The clinical scoring systems have not been represented in this table. Please refer to the individual papers for these details.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Wells PS et al,
2000,
Canada
964 (derivation) and 247 (validation) patients referred for V/Q scan from earlier cohortRetrospective clinical decision rule study% of patients with PE in low risk7.8% (5.9-10.1) in derivation group, 5.1% (2.3-9.4) in validation setUse of previous cohort of patients Includes inpatients
Wicki J et al,
2001,
Switzerland
1090 emergency ward patients with suspected PE Decision rule developed which divides patients into low medium and high risk groupsProspective clinical decision rule studyPretest probability of PE

Low

Medium

High


10%

38%

81%
Reference standard included nondiagnostic scan No Validation study
Kline JA et al,
2002,
USA
Convenience sample 934 patients presenting to 7 EDs, who underwent pulmonary vascular imaging for PE Decision rule developed which divides patients into high and low risk groupsProspective clinical decision rule studyPretest probability of PE

Low

High


13.3% (10.915.9)

42.1% (35.3-49.6)
The authors suggest that the decision rule would determine a low risk group suitable for application of a D-dimer test this has yet to be validated.
Miniati M et al,
2003,
Italy
1100 consecutive patients referred for investigation for PEDerivation/Cross Validation studyObjective signs, risk factors, ECG and CXR recorded.Multivariate logistic regression established those associated with the diagnosis of PEScoring system developed which divides patients into low, intermediate, moderately high and high groups

Pre-test probability by group
Low- 4%
Intermediate- 22%
Moderately high- 74%
High- 98%
Subjective inclusion criteria No prospective validation study (cross validation only)

Comment(s)

There is evidence to suggest a variety of clinical models can be used to stratify patients into different levels of risk for PE. It is possible that these may be combined with other tests to give an acceptably low post-test probability of PE.

Clinical Bottom Line

Clinical risk stratification is a potentially useful method of identifying low risk patients in whom PE may be safely excluded by simple non-invasive tests.

References

  1. Wells PS, Anderson MR, Ginsberg JS, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. Thromb Heamost 2000;83(3):416-20.
  2. Wicki J, Perneger TV, Junod AF, et al. Assessing clinical probability of pulmonary embolism in the emergency ward: A simple score. Arch Intern Med 2001;161(1):92-97.
  3. Kline JA, Nelson RD, Jackson RE, et al. Criteria for the safe use of D-dimer testing in emergency department patients with suspected pulmonary embolism: a multicenter US study. Ann Emerg Med 2002;39(2):144152.
  4. Miniati M, Monti S, Bottai M. A structured clinical model for predicting the probability of pulmonary embolism. Am J Med 2003;114:173-9.