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Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED)

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ClinicalTrials.gov Identifier: NCT00000566
Recruitment Status : Completed
First Posted : October 28, 1999
Last Update Posted : April 15, 2016
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI)

Brief Summary:
To evaluate the sensitivity and specificity of two major, widely used technologies, radionuclear imaging (ventilation-perfusion scanning) and pulmonary angiography, for the diagnosis of pulmonary embolism.

Condition or disease Intervention/treatment Phase
Lung Diseases Pulmonary Embolism Procedure: ventilation-perfusion ratio Procedure: angiography Phase 3

Detailed Description:


In 1983, reliable data on the incidence of pulmonary embolism in the adult population and in groups identified at risk were not available because the sensitivity and specificity of the diagnostic procedures had not been determined. Estimates suggested there were about half a million episodes of pulmonary embolism in hospitalized patients each year in the United States. Deaths attributable to pulmonary embolism would be expected in about one third of these patients if left untreated.

The clinical diagnosis of pulmonary embolism was subject to a high frequency of false positives and false negatives. The most definitive diagnostic procedure was pulmonary angiography, an invasive, expensive procedure which was not without risk. It required specialized equipment and highly trained personnel both for performance and for interpretation. Therefore, it was used to diagnose pulmonary embolism only in the major medical centers. Another technique utilized as a method to diagnose pulmonary embolism involved a combination of perfusion and ventilation scanning; this method was only minimally invasive. A normal perfusion scan was thought to be of considerable value because it essentially excluded the diagnosis of pulmonary embolism. In selected patient populations, abnormal perfusion scans combined with normal ventilation scans were of substantial help in diagnosis.

Although there had been no acceptable validation of the use of perfusion scans in the diagnosis of pulmonary embolism, thousands of patients had been evaluated for pulmonary embolism based on perfusion scanning often using methods of imaging now considered to be inadequate. In the early 1980s, clinical practice interpreted a negative perfusion scan as overwhelming evidence against the presence of pulmonary emboli. This interpretation had not been adequately tested either in a prospective study or by long-term follow-up of patients to determine clinical outcome. With regards to positive perfusion scans, there were data to suggest that as many as two-thirds of positive perfusion scans could not subsequently be confirmed by pulmonary angiography. Prospective studies in which timely angiograms using selective injections and improved imaging techniques were needed to evaluate the usefulness of positive perfusion scans.

Phase I was initiated in September 1983. Protocols developed during Phase I underwent independent assessment review in April 1984 and were reviewed and approved by the May 1984 National Heart, Lung, and Blood Advisory Council. Recruitment and intervention started in January 1985 and ended in September 1986. Follow-up was completed on September 30, 1987.


Patients suspected of pulmonary embolism underwent a ventilation-perfusion scan. Patients with an abnormal perfusion scan underwent angiography. All patients were followed for one year.

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Study Type : Interventional  (Clinical Trial)
Primary Purpose: Diagnostic
Study Start Date : September 1983
Study Completion Date : December 1989

Resource links provided by the National Library of Medicine

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 75 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Men and women suspected of having a pulmonary embolism and who met the criteria to undergo angiography.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00000566

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
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OverallOfficial: Abass Alavi University of Pennsylvania
OverallOfficial: Richard Greenspan Yale University
OverallOfficial: Charles Hales Massachusetts General Hospital
OverallOfficial: Herbert Saltzman Duke University
OverallOfficial: Paul Stein Henry Ford Hospital
OverallOfficial: John Weg University of Michigan
Study Data/Documents: Individual Participant Data Set  This link exits the ClinicalTrials.gov site
Identifier: PIOPED
NHLBI provides controlled access to IPD through BioLINCC. Access requires registration, evidence of local IRB approval or certification of exemption from IRB review, and completion of a data use agreement.


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ClinicalTrials.gov Identifier: NCT00000566    
Other Study ID Numbers: 204
First Posted: October 28, 1999    Key Record Dates
Last Update Posted: April 15, 2016
Last Verified: June 2002
Additional relevant MeSH terms:
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Lung Diseases
Pulmonary Embolism
Respiratory Tract Diseases
Embolism and Thrombosis
Vascular Diseases
Cardiovascular Diseases