Age-ism in d-dimers

This is something that has been a bug bear of many a physician for years. Your gestalt and experience downtrodden by a slightly raised d-dimer that should not have been sent in the first place. Here's a reason why you should have that leeway.


Original article via Medscape.com:

Pulmonary Embolism Guidelines Released by ACP

Beth Skwarecki
September 28, 2015
New pulmonary embolism guidelines suggest that computed tomography (CT) imaging and plasma D-dimer testing are overused in patients suspected of having a pulmonary embolism, and may do more harm than good. The American College of Physicians (ACP) published the guidelines online September 29 in the Annals of Internal Medicine.
Plasma D-dimer tests are more appropriate for those at intermediate risk for a pulmonary embolism, and no testing may be necessary for some patients at low risk.
"Although the use of [computed tomography] for the evaluation of patients with suspected [pulmonary embolism] is increasing in the inpatient, outpatient, and [emergency department] settings, no evidence indicates that this increased use has led to improved patient outcomes," write Ali S. Raja, MD, vice chair, Department of Emergency Medicine, Massachusetts General Hospital, Boston, and colleagues from the ACP's Clinical Guidelines Committee. Potential harms of unnecessary imaging include increased costs, radiation exposure, and follow-up for incidental findings.
Instead, the authors recommend using either the Wells or Geneva rules to choose tests based on a patient's risk for pulmonary embolism.
If the patient is at low risk, clinicians should use the eight Pulmonary Embolism Rule-Out Criteria (PERC); if a patient meets all eight criteria, the risks of testing are greater than the risk for embolism, and no testing is needed. "By avoiding D-dimer testing in these low-risk patients, physicians can avoid false-positive D-dimer results and subsequent CT, which is unnecessary. Of note, the PERC should not be applied to patients at intermediate or high risk for [pulmonary embolism]," they write.
For patients at intermediate risk, or for those at low risk who do not meet all of the rule-out criteria, the authors recommend a high-sensitivity plasma D-dimer test as the initial test. In patients older than 50 years, the authors recommend using an age-adjusted threshold (age × 10 ng/mL, rather than a blanket 500 ng/mL) because normal D-dimer levels increase with age. Patients with a D-dimer level below the age-adjusted cutoff should not receive any imaging studies. Patients with elevated D-dimer levels should then receive imaging.
Patients at high risk should skip the D-dimer test and proceed to CT pulmonary angiography, because a negative D-dimer test will not eliminate the need for imaging in these patients. Clinicians should only obtain ventilation-perfusion scans in patients with a contraindication to CT pulmonary angiography or if CT pulmonary angiography is unavailable.
The new guidelines are being released as a Best Practice Advice statement, meant to guide but not replace clinicians' judgement, based on a nonsystematic literature review.
One author reports that he chairs the Test-Writing Committee for the secure examination of the American Board of Internal Medicine. Another reports that he chaired the Quality and Performance Committee of the American College of Emergency Physicians, in which capacity he helped to develop performance measures of appropriate use of computed tomography for pulmonary embolism. The other authors have disclosed no relevant financial relationships.
Ann Intern Med. Published online September 29, 2015.