Methodology Score: 4/5
Usefulness Score: 4.5/5

Kearon C, et al. N Engl J Med. 2019 Nov 28;381(22):2125-2134

Question and Methods: the authors sought to demonstrate safety using a d-dimer cut-off of 1000ng/mL for low pre-test probability patients & a cut-off of 500ng/mL for moderate pre-test probability patients.

Findings: Of 1325 patients with low or moderate pre-test probability and negative corresponding graduated D-dimer levels, 0% (95% CI 0.00 – 0.29%) had VTE at 90 days.

Limitations: This was not a randomized controlled trial, and the moderate pre-test probability cohort may have been vulnerable to sampling bias.

Interpretation: PE can be safely ruled out if a D-dimer level <1000ng/mL is found in those with well’s <4.0; further study is needed before the investigators’ approach to the moderate pre-test probability patient is adopted.

By: Dr. Doran Drew

Hans Rosenberg
Dr. Rosenberg is an emergency physician at the Ottawa Hospital, assistant professor at the University of Ottawa, and Director of the Digital Scholarship and Knowledge Dissemination Program.