Abstract 1: Diagnosis of pulmonary embolism with d-dimer adjusted

Diagnosis of pulmonary embolism with d-dimer adjusted to clinical probability Kearon C, de Wit K, Parpia S, et al. N Engl J Med. 2019;381(22):2125-2134.

SUMMARY:

• The best way to use d-dimer testing has been a subject of intense debate, and many studies and rules have been published regarding how use d-dimer testing and more recently PE graduated d-dimer (PEGeD) in the workup of potential age-adjusted pulmonary embolism (PE)-years.
• PEGeD uses a strategy of ruling out PE in adult patients with low and moderate pretest probability by using thresholds of 1,000 ng/mL and 500 ng/mL, respectively.
• This study excluded patients who were pregnant, had less than 3 months to live, had anticoagulation for some other reason, had a medical history that would alter d-dimer levels (eg, recent major surgery), or received a chest CT or d-dimer testing before they could be enrolled.
• Physicians used the 7-item Wells clinical-prediction rule (scores from 0 to 12.5) to categorize the patients as having low (0-4.0), moderate (4.5-6.0), or high (≥6.5) Wells scores; the patients with low and moderate pretest probability received d-dimer testing.
• According to the management algorithm, patients with low pretest probability and a d-dimer level <1,000 ng/mL and patients with moderate pretest probability and a d-dimer level <500 ng/mL were discharged with no imaging or anticoagulation; all other patients received CT.
• The study enrolled 2,017 patients with signs or symptoms of PE (86.9% with low pretest probability (PTP), 10.8% with moderate PTP, and 2.3% with high PTP) over 3 years.
• PE was diagnosed in 7% of low-PTP patients, 20% of moderate-PTP patients, and 40% of high-PTP patients.
• Of the 1,970 patients (97.7% of the total) with low or moderate PTP of PE, 67.3% had negative d-dimer test results, and none had a venous thromboembolism in follow-up.
• With the PEGeD strategy, a CT pulmonary angiogram would have been performed on 34.3% of patients; if the traditional threshold of 500 ng/mL had been used on all patients, CT would have been performed on 51.9% of patients, representing an absolute reduction of 17.6% and a relative difference of 33.9% with zero missed cases.
• Follow-up at 90 days was impressive: only <5% of patients were lost to follow-up (none in the moderate or high groups).

PMID: 31774957

EDITOR’S COMMENTARY: In this prospective management study, the authors show that raising the d-dimer threshold to 1,000 ng/mL (500 ng/mL if using DDU) for patients with low Wells PTP is a safe way to significantly decrease the need for CT pulmonary angiograms when working up patients for PE.

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