D-dimer concentration increases with age reducing the clinical value of the D-dimer assay in the elderly

Area of Science:

• Clinical Chemistry
• Hematology
• Diagnostic Medicine

Background:

• The D-dimer assay is a crucial exclusion test for venous thromboembolic disease.
• A negative D-dimer result indicates a low probability of thrombosis.
• This study investigates the impact of aging on D-dimer assay performance.

Purpose of the Study:

• To evaluate the influence of age on the specificity and sensitivity of the Vidas D-dimer assay.
• To determine optimal D-dimer threshold values for different age groups.
• To assess the clinical utility of the D-dimer assay in elderly populations.

Main Methods:

• Analysis of D-dimer results from 6631 unselected patients aged over 16 years, stratified into four age groups.
• Evaluation of assay specificity in a separate cohort of 1897 patients with suspected venous thromboembolic disease.
• Calculation of median D-dimer concentrations and assay specificity across age demographics.

Main Results:

• Median D-dimer concentration significantly increases with age.
• Assay specificity declines sharply in older age groups, dropping below 5% in those over 80.
• Increasing the D-dimer threshold to 1000 ng/mL improved specificity to 55% in the 60-80 age group without compromising sensitivity.

Conclusions:

• The standard 500 ng/mL D-dimer threshold has limited clinical value for excluding thrombosis in patients over 80.
• Assay specificity in the 60-80 age group is poor (26%) but can be enhanced by raising the threshold.
• Prospective trials are recommended to validate a higher D-dimer threshold for older patients.