title: Assessing 2 D-dimer age-adjustment strategies to optimize computed tomographic use in ED evaluation of pulmonary embolism.
abstract: OBJECTIVE
  Validate the sensitivity and specificity of 2 age adjustment strategies for d-dimer values in identifying patients at risk for pulmonary embolism (PE) compared with traditional D-dimer cutoff value (500 ng/mL) to decrease inappropriate computed tomography pulmonary angiography (CTPA) use.
  
  
  METHODS
  This institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study included all adult emergency department patients evaluated for PE over a 32-month period (1/1/11-8/30/13). Only patients undergoing CTPA and D-dimer testing were included. We used a validated natural language processing algorithm to parse CTPA radiology reports and determine the presence of acute PE. Outcome measures were sensitivity and specificity of 2 age-adjusted D-dimer cutoffs compared with the traditional cutoff. We used χ2 tests with proportional analyses to assess differences in traditional and age-adjusted (age×10 ng/mL) D-dimer cutoffs, adjusting both by decade and by year.
  
  
  RESULTS
  A total 3063 patients with suspected PE were evaluated by CTPA during the study period, and 1055 (34%) also received d-dimer testing. The specificity of age-adjusted D-dimer values was similar or higher for each age group studied compared with traditional cutoff, without significantly compromising sensitivity. Overall, had decade age-adjusted cutoffs been used, 37 CTPAs could have been avoided (19.6% of 189 patients aged >60 years with Wells score≤4); had yearly age-adjusted cutoffs been used, 52 CTPAs (18.2% of 286 patients aged >50 years with Wells score≤4) could have been avoided.
  
  
  CONCLUSIONS
  Each age-adjusted D-dimer cutoff strategy for the evaluation of PE was associated with increased specificity and statistically insignificant decreased sensitivity when compared with the traditional D-dimer cutoff value.
authors.affiliation: Center for Evidence-Based Imaging, Brigham and Women's Hospital, Brookline, MA; Department of Radiology, Brigham and Women's Hospital, Boston, MA; Department of Emergency Medicine, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA. Electronic address: anuraggz@gmail.com.
authors.forename: Anurag
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Center for Evidence-Based Imaging, Brigham and Women's Hospital, Brookline, MA; Department of Radiology, Brigham and Women's Hospital, Boston, MA; Department of Emergency Medicine, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA.
authors.forename: Ali S
authors.initials: AS
authors.lastname: Raja
authors.affiliation: Center for Evidence-Based Imaging, Brigham and Women's Hospital, Brookline, MA; Department of Radiology, Brigham and Women's Hospital, Boston, MA; Department of Medicine, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA.
authors.forename: Ivan K
authors.initials: IK
authors.lastname: Ip
authors.affiliation: Center for Evidence-Based Imaging, Brigham and Women's Hospital, Brookline, MA; Department of Radiology, Brigham and Women's Hospital, Boston, MA; Harvard Medical School, Boston, MA.
authors.forename: Ramin
authors.initials: R
authors.lastname: Khorasani
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D004636:Emergency Service, Hospital; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D