Diagnosis of Pulmonary #Embolism with d-#Dimer Adjusted to Clinical Probability

Retrospective analyses suggest that pulmonary embolism is ruled out by a d-dimer level of less than 1000 ng per milliliter in patients with a low clinical pretest probability (C-PTP) and by a d-dimer level of less than 500 ng per milliliter in patients with a moderate C-PTP

..We performed a prospective study in which pulmonary embolism was considered to be ruled out without further testing in outpatients with a low C-PTP and a d-dimer level of less than 1000 ng per milliliter or with a moderate C-PTP and a d-dimer level of less than 500 ng per milliliter.

..Our diagnostic strategy resulted in the use of chest imaging in 34.3% of patients, whereas a strategy in which pulmonary embolism is considered to be ruled out with a low C-PTP and a d-dimer level of less than 500 ng per milliliter would result in the use of chest imaging in 51.9% (difference, −17.6 percentage points; 95% CI, −19.2 to −15.9).

CONCLUSIONS
A combination of a low C-PTP and a d-dimer level of less than 1000 ng per milliliter identified a group of patients at low risk for pulmonary embolism during follow-up.

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