is a by-product of fibrin cross-linking that is produced during clot formation. Elevated D-dimer levels are associated with
ongoing clot formation. As people age, their normal D-dimer levels increase. Because of this, the normal cutoff value for a D-dimer test (< 500 mcg/L) loses
specificity in older patients. An age-adjusted cutoff value (calculated as age X 10
) has been proposed as a means to increase the specificity of the D-dimer test in
patients older than 50 years.
ADJUST-PE STUDY (2014)
- PubMed abstract
- The ADJUST-PE study enrolled 3346 consecutive patients presenting to an ER with clinical suspicion of pulmonary embolism (PE) defined
as an acute onset or worsening shortness of breath or chest pain without another obvious etiology
- Main exclusion criteria: CrCl ≤ 30 ml/min; receiving anticoagulant therapy for another indication (e.g. a fib)
- Patients were assessed in the following manner:
- Clinical probability of PE was assessed with the Geneva score or the 2-level Wells score (score ≤ 4 - unlikely; score > 4 - likely)
- Patients with high (Geneva) or a likely (Wells) clinical probability proceeded directly to CT scan
- In patients with a low/intermediate or unlikely clinical probability, a D-dimer test was performed
- The D-dimer result was interpreted according to the age-adjusted cutoff: in patients younger than 50 years, PE was excluded in those with a D-dimer value lower than 500 μg/L.
In patients 50 years or older, the D-dimer test result was considered negative in those with a D-dimer value lower than their age multiplied by 10.
- PRIMARY OUTCOME: The primary outcome was the failure rate of the diagnostic strategy, defined as the rate of adjudicated
symptomatic thromboembolic events during the 3-month follow-up period among patients not treated with anticoagulants on the basis of a negative D-dimer test result according to
the age-adjusted cutoff
- 2898 patients had unlikely or non-high clinical probability of PE
- 1744 patients had a D-dimer ≥ age-adjusted cutoff and underwent CT scanning
- 817 patients had a D-dimer < 500 μg/L - Of these patients, 1 patient had an adjudicated thromboembolic event during follow-up (0.1%, CI 0% - 0.7%)
- 337 patients had a D-dimer > 500 μg/L, but < age-adjusted cutoff - Of these patients, 1 patient had an adjudicated thromboembolic event during follow-up (0.3%, CI 0.1% - 1.7%)
- Age-adjusted D-dimer cutoffs performed well in this study and in other studies (see BMJ study). Using age-adjusted
cutoffs will likely help save money and conserve resources in older patients with a low probability of PE.