Dr. Erika Kancler
Context: D-dimer measurements are vital in the diagnosis and exclusion of venous thromboembolism (VTE). D-dimer levels increase with age, causing many older individuals to be subject to unnecessary imaging in the diagnostic process. The implementation of an age-adjusted D-dimer may help to improve specificity of the test, therefore, preventing further imaging.
Objective: To assess whether the application of age-adjusted cutoff values (age x 10 μg/L) compared to a conventional cutoff value (500 μg/L) improves diagnostic accuracy of the D-dimer test in older individuals (>50 years) with suspected venous thromboembolism (VTE) without compromising safety.
Methods: A PubMed search was conducted utilizing the term “age-adjusted D-dimer” with the addition of the MeSH terms “Sensitivity and Specificity” and limitation to English studies from the past five years. A review was performed on three studies that compared the efficacy of age-adjusted D-dimer to conventional cutoff values in patients > 50 years old.
Results: Scouten et al. found that the specificity of the conventional cutoff decreased with age, from 66.8% in patients less than 50 to 14.7% in those aged >80. Specificity was increased to 35.2% with the use of age-adjusted cutoffs. Sensitivities remained above 97% with the age-adjusted cutoff in all categories. Sharp et al. found that the age-adjusted D-dimer threshold was more specific (64%) versus the conventional cutoff off 500 μg/L (54%), but less sensitive (93% versus 98%). Righini et al. found that the sensitivity of the D-dimer test did not change with the application of an age-adjusted threshold, but the specificity increased from 30.8% to 43.5% versus the conventional cutoff.
Conclusion: The use of age-adjusted values for the D-dimer test improves specificity without compromising sensitivity, effectively improving clinical usefulness of the D-dimer test and reducing imaging among patients >50 years with suspected venous thromboembolism (VTE).
Caldwell PN, Zimmerman KZ. Age-adjusted vs conventional D-dimer thresholds in the diagnosis of venous thromboembolism. JMU Scholarly Commons Physician Assistant Capstones. http://commons.lib.jmu.edu/pacapstones/20. Published May 16, 2017.