Assessment of the safety and efficiency of using an age-adjusted D-dimer threshold to exclude suspected pulmonary embolism.
BACKGROUND
D-dimer levels increase with age, and research has suggested that using an age-adjusted D-dimer threshold may improve diagnostic efficiency without compromising safety. The objective of this study was to assess the safety of using an age-adjusted D-dimer threshold in the workup of patients with suspected pulmonary embolism (PE).


METHODS
We report the outcomes of 923 patients aged > 50 years presenting to our ED with suspected PE, a calculated Revised Geneva Score (RGS), and a D-dimer test. All patients underwent CT pulmonary angiography (CTPA). We compared the false-negative rate for PE of a conventional D-dimer threshold with an age-adjusted D-dimer threshold and report the proportion of patients for whom an age-adjusted D-dimer threshold would obviate the need for CTPA.


RESULTS
Among 104 patients with a negative conventional D-dimer test result and an RGS ≤ 10, no PE was observed within 90 days (false-negative rate, 0%; 95% CI, 0%-2.8%). Among 273 patients with a negative age-adjusted D-dimer result and an RGS ≤ 10, four PEs were observed within 90 days (false-negative rate, 1.5%; 95% CI, 0.4%-3.7%). We observed an 18.3% (95% CI, 15.9%-21.0%) absolute reduction in the proportion of patients aged > 50 years who would merit CTPA by using an age-adjusted D-dimer threshold compared with a conventional D-dimer threshold.


CONCLUSIONS
Use of an age-adjusted D-dimer threshold reduces imaging among patients aged > 50 years with an RGS ≤ 10. Although the adoption of an age-adjusted D-dimer threshold is probably safe, the CIs surrounding the additional 1.5% of PEs missed necessitate prospective study before this practice can be adopted into routine clinical care.
Department of Medicine, Intermountain Medical Center, Murray, UT; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT. Electronic address: scott.woller@imail.org.
Scott C
SC
Woller
Department of Medicine, Intermountain Medical Center, Murray, UT; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT.
Scott M
SM
Stevens
Tufts Medical Center Department of Radiology, Boston, MA.
Daniel M
DM
Adams
Department of Medical Informatics, LDS Hospital, Salt Lake City, UT.
R Scott
RS
Evans
Department of Medical Informatics, LDS Hospital, Salt Lake City, UT.
James F
JF
Lloyd
Department of Medical Statistics, LDS Hospital, Salt Lake City, UT.
Gregory L
GL
Snow
Department of Emergency Medicine, Intermountain Medical Center, Murray, UT.
Joseph R
JR
Bledsoe
Department of Ophthalmology, Georgia Regents University, Augusta, GA.
David Z
DZ
Gay
Intermountain Riverton Hospital, Riverton, UT.
Richard M
RM
Patten
Department of Medicine, Intermountain Medical Center, Murray, UT; Division of Pulmonary and Critical Care Medicine, Intermountain Medical Center, Murray, UT.
Valerie T
VT
Aston
Department of Medicine, Intermountain Medical Center, Murray, UT; Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT.
C Gregory
CG
Elliott
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D016001:Confidence Intervals; D004636:Emergency Service, Hospital; D005188:False Negative Reactions; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D061214:Patient Safety; D011655:Pulmonary Embolism / Q000097:blood* / Q000175:diagnosis*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D015415:Biomarkers; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D