Suspected pulmonary embolism and lung scan interpretation: trial of a Bayesian reporting method.
OBJECTIVE
To determine whether a Bayesian method of lung scan (LS) reporting could influence the management of patients with suspected pulmonary embolism (PE).


METHODS
1) A descriptive study of the diagnostic process for suspected PE using the new reporting method; 2) a non-experimental evaluation of the reporting method comparing prospective patients and historical controls; and 3) a survey of physicians' reactions to the reporting innovation.


METHODS
University of Virginia Hospital.


METHODS
Of 148 consecutive patients enrolled at the time of LS, 129 were completely evaluated; 75 patients scanned the previous year served as controls.


METHODS
The LS results of patients with suspected PE were reported as posttest probabilities of PE calculated from physician-provided pretest probabilities and the likelihood ratios for PE of LS interpretations.


RESULTS
Despite the Bayesian intervention, the confirmation or exclusion of PE was often based on inconclusive evidence. PE was considered by the clinician to be ruled out in 98% of patients with posttest probabilities less than 25% and ruled in for 95% of patients with posttest probabilities greater than 75%. Prospective patients and historical controls were similar in terms of tests ordered after the LS (e.g., pulmonary angiography). Patients with intermediate or indeterminate lung scan results had the highest proportion of subsequent testing. Most physicians (80%) found the reporting innovation to be helpful, either because it confirmed clinical judgement (94 cases) or because it led to additional testing (7 cases).


CONCLUSIONS
Despite the probabilistic guidance provided by the study, the diagnosis of PE was often neither clearly established nor excluded. While physicians appreciated the innovation and were not confused by the terminology, their clinical decision making was not clearly enhanced.
Becker
D M
DM
Department of Medicine, University of Virginia School of Medicine, Charlottesville 22908.
Philbrick
J T
JT
Schoonover
F W
FW
Teates
C D
CD
D000328:Adult; D000368:Aged; D001291:Attitude of Health Personnel; D001499:Bayes Theorem; D002983:Clinical Competence; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000401:mortality / Q000503:physiopathology; D011857:Radiographic Image Interpretation, Computer-Assisted; D013668:Technetium Tc 99m Aggregated Albumin; D014692:Ventilation-Perfusion Ratio; D014980:Xenon Radioisotopes
D013668:Technetium Tc 99m Aggregated Albumin; D014980:Xenon Radioisotopes