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Three Part Question

In [a patient presenting with features suggestive of pulmonary embolus] what is [the diagnostic utility of chest X-Ray] in [stratifying risk of pulmonary embolus]?

Clinical Scenario

A thirty year old man presents to the department with a spontaneous onset of atraumatic pleuritic chest pain. He is in a low risk group clinically. You wonder whether a chest X-Ray will help to safely exclude a pulmonary embolus.

Search Strategy

Medline 1950- November week 3 2008 using the OVIDSP interface.
[exp Pulmonary Embolism OR exp Thromboembolism OR PE.mp OR pulmonary infarct$.mp OR pulmonary embol$.mp] AND [exp Radiography, Thoracic OR chest Xray.mp OR Chest X-Ray.mp OR CXR.mp OR chest radiograph$.mp] LIMIT to human.

Search Outcome

727 papers were found. To be included, the study had to report sufficient data to assess the diagnostic utility of the chest X-ray (CXR). Studies reporting scoring systems, without enough detail to ascertain the utility of a CXR alone, were not included. Several publications on the PIOPED data were identified. Only one PIOPED paper reporting sensitivity and specificity has been included in this analysis.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Worsley DF et al, 1993, USA	1063 inpatients suspected of pulmonary embolus from previous (PIOPED) prospective diagnostic study database who had had a CXR	Retrospective diagnostic study from previous prospectively acquired data	Sensitivity (Sn) and Specificity (Sp) of abnormal CXR and of various individual abnormalities	'Abnormal' CXR alone 88% Sn 18% Sp Individual signs vary. Sn 8-35% Sp 70-96%	Retrospective reanalysis (albeit of prospective data) Inpatient population only
Stollberger C et al, 2000, Austria	168 (derivation) and 139 (validation) inpatients suspected of pulmonary embolus	Prospective Derivation/Validation study	Risk factors, objective clinical signs, LDH, ECG, Arterial blood gases, Venography/Plethysmography results and CXR (normal or abnormal with or without defined signs of PE) recorded Multivariate logistic regression established those associated with the diagnosis of PE	'Abnormal' CXR alone Sn 66% and Sp 6% Individual signs vary. Sn 6-21% Sp 69-94%	Small sample size Inpatient population only
Greenspan et al, 1982, USA	Convenience retrospective sample of 108 patients with angiographically proven PE and 44 patients negative for PE	Retrospective diagnostic	Sensitivity and specificity of 8 radiologists and one medical intern at diagnosing PE when reporting chest X-rays	Sensitivity 33% Specificity 59%	Sample highly selected X-rays interpreted by radiology and medical doctors, not emergency doctors
Stein et al, 1987, USA	Convenience sample of 169 patients with angiographically proven PE from 2 previous studies. (Some overlap with the above cohort of patients)	Retrospective diagnostic	Radiographical abnormalities as reported by the consensus of 3 radiologists	76% had one or more abnormalities 24% had normal chest X-rays Frequency of normal chest X-rays similar among those with massive PE and those with sub-massive PE	Sample highly selected Some patients also included in Greenspan study – unclear how many X-rays interpreted by radiology doctors, not emergency doctors
Elliot et al, 2000, International	2322 patients diagnosed with PE 1995-96, at 53 centres internationally	Prospective Cohort	Normal CXR	24%	This is a cohort of patients diagnosed with PE rather than investigated for PE. No standardised diagnosis for PE. No details on how CXRs were reported.
			Cardiac enlargement	27%
			Pleural effusion	23%
			Elevated hemidiaphragm	20%
			PA enlargement	19%
			Atelectasis	18%
			Infiltrate	17%
			Pulmonary congestion	14%
			Oligemia	8%
			Pulmonary infarction	5%
			Overinflation	5%

Comment(s)

There is evidence to suggest that a chest X-Ray alone has inadequate sensitivity or specificity to rule out or in a pulmonary embolus, though it may feature as part of risk stratification strategies.

Editor Comment

CXR, chest x ray; ECG, electrocardiogram; LDH, lactate dehydrogenase; PA, pulmonary artery; PE, pulmonary embolism.

Clinical Bottom Line

A chest X-ray alone is of little value in the diagnosis of pulmonary embolus. Its main value is in ruling out other causes of the presenting symptoms, or as part of a risk stratification strategy to inform a further investigative protocol.

References

1. Worsley DF, Alavi A, Aronchick JM, et al. Chest Radiographic Findings in Patients with Acute Pulmonary Embolism: Observations from the PIOPED Study. Radiology 1993:189(1);133-136.
2. Stollberger C, Finsterer J, Lutz W, et al. Multivariate Analysis-Based Prediction Rule for Pulmonary Embolism. Thrombosis Research 2000;97(5):267-273.
3. Greenspan RH, Ravin CE, Polansky SM, et al. Accuracy of the chest radiograph in diagnosis of pulmonary embolism Investigative Radiology 1982;17(6):539-43.
4. Stein PD, Willis PW de Mets DL. Chest Roentgenogram in Patients with Acute Pulmonary Embolism and no Pre-existing Cardiac or Pulmonary Disease. American Journal of Noninvasive Cardiology 1987;1(3):171-176.
5. Elliott C, Goldhaber S, Visani L, et al. Chest radiographs in acute pulmonary embolism. Chest 2000;118(1);33-38.