D-dimer thresholds rule out pulmonary embolism, according to study

Efficiency was found to be highest when D-dimer thresholds were used in the subgroup of patients 40 years of age and younger.

The key finding was significant variability in the performance of diagnostic strategies, the researchers commented.

Adapted D-dimer thresholds based on pretest probability were effective in ruling out pulmonary embolism in subgroups of high-risk individuals without the use of imaging studies in a data review.

In a patient with probable pulmonary embolism, the diagnosis is established by radiological tests, usually computed tomographic pulmonary angiography, or ventilation and perfusion (V / Q) scan.

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“Validated clinical decision tools, such as the Wells score or the Geneva score, can be used to identify patients with a low prior probability of suffering a pulmonary embolism, in whom the D-dimer level can be verified initially, followed of imaging only if the D-dimer level is elevated, “explained Dr. Pal.

According to the authors of the new article, although current diagnostic strategies in patients with probable pulmonary embolism include the use of a validated clinical decision rule and the D-dimer test to rule out pulmonary embolism without imaging studies, they are not well studied the efficacy of dimer tests D in elderly patients advanced, in hospitalized patients, in cancer patients and other high-risk groups.

The article’s lead author, Dr. Milou AM Stals, and colleagues stated that their objective was to evaluate the safety and efficiency of the Wells rule and the revised Geneva score in combination with dimer tests D, and also the YEARS algorithm for D-dimer thresholds.

Dr. Stals of the Leiden University Medical Center in the Netherlands and the co-investigators carried out a systematic review international and data meta-analysis from individual patients that included 16 studies and 20,553 patients.

All studies had been published between January 1, 1995 and January 1, 2021. Your primary endpoints were the safety and efficiency of each of these three strategies.

In the review, the researchers defined safety as the incidence of thromboembolism venous at three months after ruling out thromboembolism lung without imaging studies at the beginning.

They defined efficiency as the proportion of patients in whom pulmonary embolism was ruled out based on the D-dimer thresholds without imaging studies.

In general, the efficiency was highest in the subgroup of patients aged 40 and under, ranging from 47% to 68% in this group. Taking into account that the efficiency was lower in patients aged 80 and over (6.0% to 23%), and in cancer patients (9.6% to 26%).

The efficiency was higher when they were used D-dimer thresholds based on the pre-test probability, compared to when they were used D-dimer thresholds fixed or age-adjusted.

The key finding was significant variability in the performance of diagnostic strategies, the researchers said.

“The overall predicted failure rate was higher for strategies incorporating tailored D-dimer thresholds. However, at the same time, the overall predicted efficiency was considerably higher with these strategies than with strategies based on a dimer threshold. D fixed too “.

Since the benefits of each of the three diagnostic strategies depend on their correct application, the researchers recommended that an individual hospitalist select a strategy for their institution.

“Whether clinicians should rely on the Wells rule, the YEARS algorithm, or the revised Geneva score becomes a matter of local preference and experience,” wrote Dr. Stals and colleagues.

Study results were limited by several factors, including differences between studies in score predictors and D-dimer trials. Another limitation was that differential verification biases for classifying fatal events and pulmonary embolism can have contributed to overestimating the failure rates of the adapted D-dimer thresholds.

The strengths of the study were its large sample size and original data on pre-test probability, and that the data support the use of any of the three strategies to rule out pulmonary embolism in identified subgroups without the need for imaging tests. the authors wrote.

“Until the results of ongoing randomized diagnostic trials are available, clinicians and guideline committees should balance the trade-off between safety and efficacy of available diagnostic strategies,” they concluded.

The tailored D-dimer benefits some patients “Clearly, raising the D-dimer threshold will reduce the number of patients requiring radiographic imaging (improved specificity), but this carries the risk of missing pulmonary embolism (less sensitivity) .

Is that risk worth taking? “Asks Dr. Daniel J. Brotman of the Johns Hopkins University, in Baltimore.

Dr. Brotman is not surprised by the results of the study.

“Conditions and disorders that predispose to thrombosis through activation of hemostasis – such as advanced age, cancer, inflammation, prolonged hospitalization, and trauma raise D-dimer levels regardless of whether or not thrombosis is evident on radiological tests.” , He said.

However, these patients are unlikely to have normal D-dimer levels, regardless of the threshold used.

Tailored D-dimer thresholds may benefit some patients, including those with contraindications or limited access to imaging tests, Dr. Brotman said.

D-dimer can be used for risk stratification independent of pulmonary embolism, as patients with marginally elevated D-dimer levels have a better prognosis than those with higher D-dimer elevations, even if a small amount is missed. pulmonary thromboembolism.

Dr. Brotman noted that raising D-dimer thresholds for high-risk patients in the subgroups analyzed may prevent some from undergoing radiological testing, but doing so carries a higher risk of diagnostic failure.

Overall, “the important work of Dr. Stals and his colleagues offers the assurance that modifying the D-dimer thresholds based on age or pre-test probability, it is safe enough for widespread practice, even in high-risk groups. “

Focusing on a single strategy ‘based on local needs’ “Several validated clinical decision tools, along with age-adjusted D-dimer threshold or pre-test probability, are currently being used as diagnostic strategies for rule out pulmonary embolism, “Pal said in an interview.

The current study is important because of the limited data available on the performance of these strategies in specific groups of patients whose risk of pulmonary embolism may differ from that of the general patient population, he noted.

“Different diagnostic strategies for pulmonary embolism have variable performance in patients with age differences, active cancer, and a history of venous thrombosis,” said Dr. Pal.

“However, this study could not establish a clear preference for one strategy over others for these subgroups, and clinicians should continue to follow their hospital-specific guidelines.

“A unique strategy should be adopted in each institution based on local needs and used as a standard of care until more data is available,” he said.

“The use of D-dimer to rule out pulmonary embolism, either with a fixed threshold or with age-adjusted thresholds, can be confused in clinical settings by other comorbid conditions such as sepsis, recent surgery and, more recently, COVID-19,” added.

“Given that the results of this study do not show a clear benefit of one diagnostic strategy in relation to others in the subgroups of patients analyzed, it would be useful to perform a prospective comparison between the subgroups of interest to guide clinical decision-making,” added the Dr. Pal.

By Medscape.

Source consulted here.

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