Imaging for the clinician special section
Clinical research study
Adherence to PIOPED II Investigators' Recommendations for Computed Tomography Pulmonary Angiography

Presented at: the American Thoracic Society meeting, May 16, 2011, Denver, Colorado.
https://doi.org/10.1016/j.amjmed.2012.05.028Get rights and content

Abstract

Background

Computed tomography (CT) pulmonary angiography use has increased dramatically, raising concerns for patient safety. Adherence to recommendations and guidelines may protect patients. We measured adherence to the recommendations of Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED II) investigators for evaluation of suspected pulmonary embolism and the rate of potential false-positive pulmonary embolism diagnoses when recommendations of PIOPED II investigators were not followed.

Methods

We used a structured record review to identify 3500 consecutive CT pulmonary angiograms performed to investigate suspected pulmonary embolism in 2 urban emergency departments, calculating the revised Geneva score (RGS) to classify patients as “pulmonary embolism unlikely” (RGS  10) or “pulmonary embolism likely” (RGS > 10). CT pulmonary angiograms were concordant with PIOPED II investigator recommendations if pulmonary embolism was likely or pulmonary embolism was unlikely and a highly sensitive D-dimer test result was positive. We independently reviewed 482 CT pulmonary angiograms to measure the rate of potential false-positive pulmonary embolism diagnoses.

Results

A total of 1592 of 3500 CT pulmonary angiograms (45.5%) followed the recommendations of PIOPED II investigators. The remaining 1908 CT pulmonary angiograms were performed on patients with an RGS  10 without a D-dimer test (n = 1588) or after a negative D-dimer test result (n = 320). The overall rate of pulmonary embolism was 9.7%. Potential false-positive diagnoses of pulmonary embolism occurred in 2 of 3 patients with an RGS  10 and a negative D-dimer test result.

Conclusions

Nonadherence to recommendations for CT pulmonary angiography is common and exposes patients to increased risks, including potential false-positive diagnoses of pulmonary embolism.

Section snippets

Study Site and Population

Intermountain Medical Center is a university-affiliated tertiary medical center in Murray, Utah, and LDS Hospital is a community hospital in Salt Lake City, Utah. In 2009 and 2010, emergency department visits exceeded 83,000 and 25,000, respectively. The Intermountain Healthcare Institutional Review Board approved this Health Insurance Portability and Accountability Act-compliant study and waived written informed consent. We queried the Intermountain Healthcare Enterprise Data Warehouse and

Sample and Patient Characteristics

The reports of 5220 consecutive chest CT scans ordered from the 2 emergency departments were reviewed to identify 3500 consecutive CT pulmonary angiograms ordered between May 22, 2009, and June 30, 2010, for suspected pulmonary embolism. A total of 2755 (78.7%) CT pulmonary angiograms were performed at Intermountain Medical Center, and 745 (21.3%) CT pulmonary angiograms were performed at LDS Hospital.

Table 1 shows the clinical characteristics for all patients and subgroups prespecified by

Discussion

We found that more than half of 3500 CT pulmonary angiograms performed to investigate clinically suspected acute pulmonary embolism were not concordant with recommendations of the PIOPED II investigators. There are several possible explanations for the disparity we observed between practice and published recommendations. First, 95% of patients who underwent CT pulmonary angiography for suspected pulmonary embolism had a pretest probability of “pulmonary embolism unlikely” (RGS  10). Most

Conclusions

CT pulmonary angiogram examinations are often not concordant with expert recommendations and guidelines for investigation of suspected pulmonary embolism. Emergency department physicians order many CT pulmonary angiograms when pulmonary embolism is unlikely and sensitive D-dimer test results are negative. This practice lowers the diagnostic yield of CT pulmonary angiograms and exposes some patients to risks associated with CT pulmonary angiography, including false-positive test results and

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    Robert G. Stern, MD, Section Editor

    Funding: Supported in part by the North American Thrombosis Forum Traveling Fellowship.

    Conflict of Interest: None.

    Authorship: All authors had access to the data and played a role in writing this manuscript.

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