title: Age and sex-dependent trends in pulmonary embolism testing and derivation of a clinical decision rule for young patients.
abstract: OBJECTIVE
  Despite low prevalence of pulmonary embolism (PE) in young adults, they are frequently imaged for PE, which involves radiation exposure and substantial financial cost.
  
  
  OBJECTIVE
  Determine the use and positive proportions for PE imaging by age, differences in clinical presentation of PE by age and the projected impact of an age-targeted decision rule.
  
  
  METHODS
  Analysis of two national population-based datasets: the 2009 Nationwide Emergency Department Sample, a 20% sample of US emergency departments (EDs) and the 2003-2006 Pulmonary Embolism Rule-out Criteria (PERC) dataset, a multisite cohort of ED patients with suspected PE from 12 US EDs.
  
  
  RESULTS
  Prevalence of PE was 10 times lower in young patients (18-35 years) than in older patients (>65 years) (0.06% vs 0.60%, p<0.001), but young patients were imaged for PE almost as frequently as older patients (2.3% vs 3.2%). This resulted in a lower proportion of positive examinations in young adults than older adults (2.3% vs 17.4%, p<0.001 in women; 4.0% vs 21.4%, p<0.001 in men). Clinical predictors of PE varied by age. Tachycardia was a significant predictor of PE in older patients (OR: 1.2-1.9, p<0.001), but not young patients. Fever was a significant predictor only in young patients (OR: 1.4-7.2, p<0.01). A modification of the previously described PERC rule to include age-specific risk factors could reduce PE imaging by 51% in young patients, with a missed PE rate of 0.6% in those excluded from imaging.
  
  
  CONCLUSIONS
  Young patients are frequently imaged for PE and have lower positive imaging rates than older patients. After further validation, application of our proposed rule for excluding young patients from PE imaging could reduce imaging, increase the positive rate of imaging and result in a low rate of missed PE among those excluded from imaging.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA.
authors.forename: John
authors.initials: J
authors.lastname: Mongan
authors.affiliation: Department of Emergency Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kline
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, California, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Smith-Bindman
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003661:Decision Support Techniques; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000453:epidemiology*; D017678:Sex Distribution; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: imaging, CT/MRI; pulmonary embolism; thrombo-embolic disease, diagnosis