Accuracy of clinical assessment in the diagnosis of pulmonary embolism

To provide clinical diagnostic criteria for pulmonary embolism (PE), we eva luated 750 consecutive patients with suspected PE who were enrolled in the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA -PED). Prior to perfusion lung scanning, patients were examined independent ly by six pulmonologists according to a standardized diagnostic protocol. S tudy design required pulmonary angiography In all patients with abnormal sc ans. Patients are reported as two distinct groups: a first group of 500, wh ose data were analyzed to derive a clinical diagnostic algorithm for Pt, an d a second group of 250 in whom the diagnostic algorithm was validated. PE was diagnosed by angiography in 202 (40%) of the 500 patients in the first group. A diagnostic algorithm was developed that Includes the identificatio n of three symptoms (sudden onset dyspnea, chest pain, and fainting) and th eir association with one or more of the following abnormalities: electrocar diographic signs of right ventricular overload, radiographic signs of olige mia, amputation of hilar artery, and pulmonary consolidations compatible wi th infarction. The above three symptoms (singly or in some combination) wer e associated with at least one of the above electrocardiographic and radiog raphic abnormalities in 164 (81%) of 202 patients with confirmed PE and in only 22 (7%) of 298 patients without PE, The rate of correct clinical class ification was 88% (440/500). In the validation group of 250 patients the pr evalence of PE was 42% (104/250). In this group, the sensitivity and specif icity of the clinical diagnostic algorithm for PE were 84% (95% CI: 77 to 9 1%) and 95% (95% CI: 91 to 99%), respectively. The rate of correct clinical classification was 90% (225/250). Combining clinical estimates of PE, deri ved from the diagnostic algorithm, with independent. Interpretation of perf usion lung scans helps restrict the need for angiography to a minority of p atients with suspected PE.