A recently published retrospective study in the Annals of EM supports the use of an age-adjusted d-dimer cutoff when evaluating patients with possible PE.

Standard cutoff = 500 ng/dL; Age-adjusted cutoff = patient’s age x 10

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Inclusion: ED visits during 2008-2013 for Kaiser Permanente South California members, age >50 years, received d-dimer test, chief complaint related to possible PE

Exclusion: patients who underwent ultrasound for DVT, PE diagnosis in previous 90 days

Outcomes: primary outcome of encounter diagnosis of acute PE.

– Calculated sensitivity, specificity, PPV, NPV.

– Collected information on age, sex, race, comorbidities, HR, O2 sat, 30-day mortality.

Results: – 31,094 patients

– 11,999 imaging studies with 507 (1.63%) diagnoses of PE

– Sensitivity decreased, but specificity increased

With an age-adjusted cutoff, there were 2,924 fewer imaging tests but 26 missed or delayed diagnoses of PE. The higher cutoff also prevented 322 cases of contrast-induced nephropathy, 29 cases of severe renal failure, 19 deaths.

An Age-adjusted D-dimer Threshold for Emergency Department Patie

There was a 2.3% rate of missed diagnoses of PE in this study. What is the clinical significance of the missed diagnoses of PE?

Other issues:

– Among those who received CTPA or V/Q scan, 10.6% had dimer < 500 ng/dL

– Among those with dimer > 500 ng/dL, 22.7% did not receive imaging

 

**Remember when evaluating patients for PE: if low pre-test probability, you can use PERC or d-dimer to help exclude PE.  (Part of ACEP Choosing Wisely Campaign)
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Source

Sharp AL, Vinson DR, Alamshaw F, Handler J, Gould MK. An Age-Adjusted D-dimer Threshold for Emergency Department Patients With Suspected Pulmonary Embolus: Accuracy and Clinical Implications. Ann Emerg Med. 2015 Aug 27. [Epub ahead of print]

ABIM Foundation. The American College of Emergency Physicians’s Choosing Wisely: ten things physicians and patient’s should question. <http://www.choosingwisely.org/doctor-patient-lists/american-college-of-emergency-physicians/> Oct 2014.