John Mongan MD, PhD, Presenter: Spouse, Employee, Quanticel Pharmaceuticals Inc

Jeffrey A Kline MD, Abstract Co-Author: Stockholder, CP Diagnostics LLC Stockholder, Studymaker LLC

Rebecca Smith-Bindman MD, Abstract Co-Author: Nothing to Disclose

Risk of carcinogenesis due to thoracic radiation exposure is higher in female compared with male, and younger compared with older patients. We compare the proportion of PE imaging (pulmonary CT angiography and V/Q scan) that results in a positive diagnosis by sex and age. As explanation for age-related differences, we investigate age-specific predictive values of common clinical indicators of PE. We develop a rule to improve testing efficiency by excluding very low risk young patients from PE imaging.

We used the 2009 Nationwide Emergency Department Sample from the Agency for Health Care Research and Quality to estimate numbers of patients in US emergency departments evaluated for PE and proportion with positive examinations. Data from the Pulmonary Embolism Research Consortium (PERC, n=7889) were used to compare significance of indicators of PE between young and older adults, and project performance of a clinical decision rule for PE imaging in young patients.

Women aged 18-35 were about an eighth as likely to have a PE than women over 50 (.06% vs .48%, RR .13 95% CI .12-.15), yet were imaged only 30% less frequently (2.7% vs 3.8%, RR .71 95% CI .66-.76), resulting in a far lower proportion of positive exams in young women (2.3% vs 12.3%, p< .001). Women were also imaged for PE more frequently, with lower proportions of positive studies, than men of the same age. Tachycardia is a significant predictor of PE in older (OR 1.41-2.11 p<.001), but not younger (OR 0.65-1.80 p=.76) patients, whereas fever is a significant predictor in younger (OR 1.46-7.38 p=.003), but not older (OR 0.65-1.04 p=.87) patients. An imaging rule incorporating these differences in indicators is projected to avoid 64% of PE studies in young adults, with a missed PE rate of 0.9% in those excluded from imaging.  

Despite low rates of PE, young women are imaged for PE almost as frequently as older patients who have much higher rates of PE. This may be in part due to imaging decisions influenced by indicators lacking significance in young patients, such as tachycardia. Limiting PE imaging to young patients with at least one significant indicator of PE can improve efficiency and expose fewer young people to radiation.

Recognition of the differences in PE presentation between young and older patients can reduce needless imaging in a radiation-sensitive demographic.

Mongan, J, Kline, J, Smith-Bindman, R, Improving Efficiency of Pulmonary Embolism Testing in Young Female Patients.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043376.html