The addition of clinical assessment to stratification according to prior cardiopulmonary disease further optimizes the interpretation of ventilation/perfusion lung scans in pulmonary embolism.

The purpose of this investigation was to test the hypothesis that prior clinical assessment among patients stratified according to the presence or absence of prior cardiopulmonary disease enhances the accuracy of the predictive value of pulmonary embolism (PE) in the various categories. Diagnostic evaluation was made on the cumulative spectrum of mismatched defects, rather than a probability based on a preassigned number of mismatched segmental equivalent defects or mismatched vascular defects. Families of curves were derived that allowed an accurate assessment of the predictive value for each category of patients. The families of curves were comparable, irrespective of whether ventilation/perfusion scans were assessed on the basis of mismatched segmental equivalent defects or mismatched vascular defects, although the latter eliminated the necessity of estimating whether segmental defects were large or moderate in size. Clinical assessment was shown to prominently affect the predictive value of PE. Prior clinical assessment among patients stratified according to prior cardiopulmonary disease enhanced the accuracy of the predictive value of PE in the various groups of patients.