Adapted D-dimer benefits some patients
“Clearly, increasing the D-dimer cutoff will lower the number of patients who require radiographic imaging (improved specificity), but this comes with a risk for missing PE (lower sensitivity). Is this risk worth taking?” Daniel J. Brotman, MD, of Johns Hopkins University, Baltimore, asked in an editorial accompanying the new study.
Dr. Brotman was not surprised by the study findings.
“Conditions that predispose to thrombosis through activated hemostasis – such as advanced age, cancer, inflammation, prolonged hospitalization, and trauma – drive D-dimer levels higher independent of the presence or absence of radiographically apparent thrombosis,” he said. However, these patients are unlikely to have normal D-dimer levels regardless of the cutoff used.
Adapted D-dimer cutoffs may benefit some patients, including those with contraindications or limited access to imaging, said Dr. Brotman. D-dimer may be used for risk stratification regardless of PE, since patients with marginally elevated D-dimers have better prognoses than those with higher D-dimer elevations, even if a small PE is missed.
Dr. Brotman wrote that increasing D-dimer cutoffs for high-risk patients in the subgroups analyzed may spare some patients radiographic testing, but doing so carries an increased risk for diagnostic failure. Overall, “the important work by Stals and colleagues offers reassurance that modifying D-dimer thresholds according to age or pretest probability is safe enough for widespread practice, even in high-risk groups.”
Focus on single strategy ‘based on local needs’
“Several validated clinical decision tools, along with age or pretest probability adjusted D-dimer threshold are currently in use as diagnostic strategies for ruling out pulmonary embolism,” Dr. Pal said in an interview.
The current study is important because of limited data on the performance of these strategies in specific subgroups of patients whose risk of PE may differ from the overall patient population, he noted.
“Different diagnostic strategies for PE have a variable performance in patients with differences of age, active cancer, and history of VTE,” said Dr. Pal. “However, in this study, no clear preference for one strategy over others could be established for these subgroups, and clinicians should continue to follow institution-specific guidance.
“A single strategy should be adopted at each institution based on local needs and used as the standard of care until further data are available,” he said.
“The use of D-dimer to rule out PE, either with fixed threshold or age-adjusted thresholds, can be confounded in clinical settings by other comorbid conditions such as sepsis, recent surgery, and more recently, COVID-19,” he said.
“Since the findings of this study do not show a clear benefit of one diagnostic strategy over others in the analyzed subgroups of patients, further prospective head-to-head comparison among the subgroups of interest would be helpful to guide clinical decision making,” Dr. Pal added.
YEARS-specific study supports D-dimer safety and value
A recent paper published in JAMA supported the results of the meta-analysis. In that study, Yonathan Freund, MD, of Sorbonne Université, Paris, and colleagues focused on the YEARS strategy combined with age-adjusted D-dimer thresholds as a way to rule out PE in PERC-positive ED patients.