Prognostic association between d-dimer thresholds and 30-day pulmonary embolism diagnosis among emergency department patients with suspected SARS-CoV-2 infection: a Canadian COVID-19 Emergency Department Rapid Response Network study.

Objective: The primary objective was to quantify the prognostic association between various D-dimer thresholds and 30-day PE diagnosis among emergency department (ED) patients with suspected SARS-CoV-2 infection.

Methods: This was a retrospective study of patients enrolled in the Canadian COVID-19 ED Rapid Response Network (CCEDRRN) registry from March 1, 2020 to July 2, 2021. We included consecutive adults (≥ 18 years) presenting to 49 EDs with chest pain, shortness of breath, hypoxia, syncope, presyncope, or hemoptysis who were tested for both SARS-CoV-2 and D-dimer at index ED visit. The primary outcome measure was the sensitivity, specificity, and negative predictive value of D-dimer test thresholds for the outcome of 30-day PE diagnosis.

Results: Among 10,837 patients included in our study, 404 (3.7%) were diagnosed with PE at 30-days. A standard D-Dimer threshold of 500 ng/mL had a sensitivity of 97.8% (95% confidence interval [CI] 95.8-99.0%), specificity of 40.9% (95% CI 39.9-41.8%), and negative predictive value of 99.8% (95% CI 99.6-99.9%). An age-adjusted D-dimer threshold had a sensitivity of 96.0% (95% CI 93.6-97.7%), specificity of 48.5% (95% CI 47.5-49.4%), and negative predictive value of 99.7% (95% CI 99.5-99.8%). D-dimer testing had slightly lower prognostic performance among SARS-CoV-2 positive compared to SARS-CoV-2 negative patients in predicting 30-day PE diagnosis.

Conclusions: Among ED patients with suspected SARS-CoV-2, the standard 500 ng/mL and age-adjusted D-dimer thresholds were comparable for the prediction of PE at 30-days. The prognostic performance of D-dimer was lower among SARS-CoV-2 positive patients.

Trial Registration: Clinicaltrials.gov, NCT04702945.