Doubling the D-Dimer Threshold in Low-Risk Patients Still Allows Pulmonary Embolism to Be Safely Ruled Out

Evidence supports adjusting D-dimer thresholds to rule out pulmonary embolism (PE) based on age or specific low-risk criteria (YEARS), but prospective evidence is lacking for elevated thresholds across broadly defined “low-risk” patients (NEJM JW Emerg Med Jul 2017 and Lancet 2017; 390:289; NEJM JW Womens Health May 2019 and N Engl J Med 2019; 380:1139). To determine the safety of doubling the D-dimer threshold to rule out PE in low-risk patients, researchers in Canada prospectively enrolled 2017 adults (66% female; mean age, 52 years) undergoing PE testing.

All patients were assessed with the Wells clinical prediction rule. PE was considered ruled out in patients with Wells scores ≤4 (low risk) if the D-dimer level was <1000 ng/mL, and in t…