• Anurag Gupta, Ali S Raja, Ivan K Ip, and Ramin Khorasani.
• 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.
• Am J Emerg Med. 2014 Dec 1; 32 (12): 1499-502.

Study ObjectiveValidate 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.MethodsThis 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.ResultsA 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.ConclusionEach 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.Copyright © 2014 Elsevier Inc. All rights reserved.

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