Age-Adjusted D-Dimer Cutoff Levels to Rule Out Pulmonary Embolism: The ADJUST-PE Study
What is the failure rate and usefulness of a strategy of combined clinical probability assessment and age-adjusted D-dimer testing (defined as age x 10 in patients 50 years or older) in emergency department patients with suspected pulmonary embolism (PE)?
This was a multicenter, international, prospective management outcome study of consecutive patients with a clinical suspicion of PE (defined as an acute onset or worsening shortness of breath or chest pain without another obvious etiology). Clinical probability was assessed with the simplified, revised Geneva score or the two-level Wells score. Those patients with a high or a likely clinical probability directly proceeded to imaging with computed tomography to evaluate for PE. D-dimer testing was performed in those with low, intermediate, or unlikely probability of PE. PE was excluded in those with a D-dimer value lower than 500 µg/L. In patients 50 years or older, an age-adjustment was performed for the D-dimer value, which was considered negative in those with a value lower than their age multiplied by 10. All patients had follow-up for 3 months. The primary outcome was the rate of adjudicated and symptomatic thromboembolic events during follow-up among patients not treated with anticoagulants on the basis of a negative D-dimer test result according to the age-adjusted cutoff.
Among 2,898 patients with a low, intermediate, or unlikely probability of PE, 337 patients (11.6%) had a D-dimer between 500 µg/L and their age-adjusted cutoff (95% confidence interval [CI], 10.5%-12.9%). The 3-month failure rate in patients with a D-dimer higher than 500 µg/L but below the age-adjusted cutoff was 1 of 331 patients (0.3%; 95% CI, 0.1%-1.7%). Overall, 766 patients were 75 years or older. Use of the age-adjusted cutoff instead of the 500 µg/L cutoff increased the proportion of patients in whom PE could be excluded (on the basis of D-dimer) from 43 of 673 patients (6.4%) to 200 of 673 patients (29.7%) without any additional false-negative findings.
A strategy that incorporates pretest clinical probability assessment and age-adjusted D-dimer laboratory testing is associated with increased diagnostic yield and low likelihood of subsequent symptomatic VTE.
In this prospective study that builds on a prior derivation and retrospective external validation study, the authors define the value of an age-adjusted D-dimer cutoff in emergency department patients with suspected PE. The use of such age-adjusted testing, when combined with clinical assessment, increases the diagnostic yield of D-dimer in older patients, and should probably be incorporated into clinical practice.
Keywords: Outcome Assessment (Health Care), Follow-Up Studies, Chest Pain, Fibrin Fibrinogen Degradation Products, Tomography, X-Ray Computed, Pulmonary Embolism
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