Using the Wells Score to categorize patients as low, moderate, or high clinical pretest probability in conjunction with adjusted positive D-dimer thresholds at >1000 ng/mL for a low or >500 ng/mL for a moderate Wells Score, the authors reduced diagnostic chest imaging in the ED with no incidence of missed venous thromboembolism (VTE) at 90 days.
Why does this matter?
We can reduce imaging for PE by increasing the D-dimer threshold or by using the D-dimer test to rule out PE in more than just patients with a low pretest probability. Historically, age-adjusted D-dimer and the YEARS criteria are examples. Using clinical pre-test probability to adjust a D-dimer threshold has also been done. PEGeD is a prospective validation of this prior work.
“Dr. Wells or: How I learned to stop imaging and love the D-dimer”
This was a multicenter, prospective trial performed in Canada which enrolled 2,017 adult patients with signs or symptoms suggestive of PE. Study outcomes were assessed at 90 days after initial diagnostic testing. When compared to a standard strategy of low clinical pretest probability and a D-dimer <500, there was a relative reduction of 34% in chest imaging using the PEGeD strategy (outlined in the Spoon Feed). Of the 1,970 patients that had low or moderate clinical pretest probability, 1,325 had negative D-dimers at the predefined thresholds and none of these patients had VTE during the 90 day follow-up. The majority of the benefit was found in the low pretest probability patients with D-dimers <1000, as only 11% patients had a moderate clinical pretest probability and only 18% of those had a negative D-dimer. The authors compared their D-dimer adjusted threshold criteria to both age-adjusted and YEARS criteria with the PEGeD strategy showing a larger reduction in imaging compared to both. Granted, this study used the Wells score to categorize patients’ pretest probability, and it is uncertain whether the same approach to D-dimer interpretation without using a clinical prediction tool would have the same result. One wonders…physician gestalt isn’t too bad.
Diagnosis of Pulmonary Embolism with d-Dimer Adjusted to Clinical Probability. N Engl J Med. 2019 Nov 28;381(22):2125-2134. doi: 10.1056/NEJMoa1909159.
Open in Read by QxMD