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