WHAT’S NEW?
We can now use d-dimer in older patients
Up until now, it was acknowledged that the simple and less expensive d-dimer test was less useful for older patients. In fact, in their 2007 clinical practice guideline on the diagnosis of VTE in primary care, the American Academy of Family Physicians and the American College of Physicians commented on the poor performance of the test in older patients.2 A more recent guideline—released by the Institute for Clinical Systems Improvement in January 2013—provided no specific guidance for patients older than 50.7 The meta-analysis reported on here, however, provides that guidance: Using an age-adjusted d-dimer cutoff improves the diagnostic accuracy of d-dimer screening in older adults.
CAVEATS
Results are not generalizable to patients at higher risk
These findings are not generalizable to all patients, particularly those at higher clinical risk who would undergo imaging regardless of d-dimer results. Not all patients included in this meta-analysis whose d-dimer was negative received imaging to confirm that they did not have VTE. As a result, the diagnostic accuracy of the age-adjusted cutoff could have been overestimated, although this is likely not clinically important because these cases would have remained symptomatic within the 45-day to 3-month follow-up period.
CHALLENGES TO IMPLEMENTATION
You, not the lab, will need to do the calculation
One of the more valuable aspects of this study is its identification of a simple calculation that can directly improve patient care. Clinicians can easily apply an age-adjusted d-dimer cutoff as they interpret lab results by multiplying the patient’s age in years × 10 μg/L. While this does not require institutional changes by the lab, hospital, or clinic, it would be helpful if the age-adjusted d-dimer calculation was provided with the lab results.
REFERENCES
1. Schouten HJ, Geersing GJ, Koek HL, et al. Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis. BMJ. 2013;346: f2492.
2. Qaseem A, Snow V, Barry P, et al; Joint American Academy of Family Physicians/American College of Physicians Panel on Deep Venous Thrombosis/Pulmonary Embolism. Current diagnosis of venous thromboembolism in primary care: a clinical practice guideline from the American Academy of Family Physicians and the American College of Physicians. Ann Fam Med. 2007;5:57-62.
3. Vossen JA, Albrektson J, Sensarma A, et al. Clinical usefulness of adjusted D-dimer cutoff values to exclude pulmonary embolism in a community hospital emergency department patient population. Acta Radiol. 2012;53:
765-768.
4. van Es J, Mos I, Douma R, et al. The combination of four different clinical decision rules and an age-adjusted D-dimer cut-off increases the number of patients in whom acute pulmonary embolism can safely be excluded. Thromb Haemost. 2012;107:167-171.
5. Deep vein thrombosis (DVT). DynaMed Web site. http://bit.ly/1gPkLoE. Accessed March 3, 2014.
6. Horlander KT, Mannino DM, Leeper KV. Pulmonary embolism mortality in the United States, 1979–1998: an analysis using multiple-cause mortality data. Arch Intern Med. 2003;163:1711-1717.
7. Dupras D, Bluhm J, Felty C, et al. Venous thromboembolism diagnosis and treatment. Institute for Clinical Systems Improvement Web site. Available at: https://www.icsi.org/_asset/sw0pgp/VTE.pdf. Accessed March 3, 2014.
ACKNOWLEDGEMENT
The PURLs Surveillance System was supported in part by Grant Number UL1RR024999 from the National Center for Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center for Research Resources or the National Institutes of Health.
Copyright © 2014. The Family Physicians Inquiries Network. All rights reserved.
Reprinted with permission from the Family Physicians Inquiries Network and The Journal of Family Practice. 2014;63(3):155-156, 158.