Safety and Validity of Pulmonary Embolism Rule-Out Criteria Evaluated

pulmoanry hypertension
pulmoanry hypertension
In patients at very low risk for pulmonary embolism, the pulmonary embolism rule-out criteria was noninferior to the conventional strategy of identifying thromboembolic events.

The use of pulmonary embolism rule-out criteria (PERC) in individuals presenting to the emergency department (ED) suspected of having a pulmonary embolism (PE) with an overall very low risk may not be inferior to conventional methods of identifying thromboembolic events, according to a study published by JAMA.

In a noninferiority, crossover cluster-randomized clinical trial ( Identifier: NCT02375919), 14 EDs in France were randomly assigned to assess patients suspected of a PE for 6 months, using the PERC-based strategy (intervention period; n=962), followed by 6 months of evaluation per usual care (control period; n=954), or in reverse order. Both periods were separated by a 2-month washout period. All individuals were followed for a period of 3 months postintervention to determine whether PEs could be safely assessed and excluded in individuals with low risk and a PERC score of 0 without additional diagnostic testing.

The primary end point was the presence of a symptomatic thromboembolic event during the 3 months after the initial ER visit. Secondary outcomes included the proportion of patients requiring a computed tomographic pulmonary angiography (CTPA), adverse events related to CTPA, ED length of stay, hospital admission rate, onset of anticoagulation therapy, hemorrhages secondary to anticoagulation therapy, and all-cause mortality at 3 months post-ED visit.

A total of 40 individuals were diagnosed with a PE: 14 in the PERC group and 26 in the control group (difference, 1.3%; 95% CI, −0.1% to 2.7%; P =.052). Overall, 48% (n=459) of individuals in the PERC group scored 0 and were classified as PERC-negative. A CTPA was used to diagnose 39 of the 40 individuals diagnosed with a PE. After 3 months of follow-up, only 1 individual in the PERC group was found to have a PE, whereas there were no identified PEs in the control group, demonstrating a difference of proportion (delta) between the 2 groups of 0.1% (1-sided 95% CI, −∞% to 0.8%).

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Individuals assessed using PERC were less likely to have CTPA performed when compared with those in the control group (129 [13%] vs 220 [23%]; difference, 9.7%; 95% CI, 6.1%-13.2%), and were more likely to have a shorter average ED length of stay (4 hours 36 minutes vs 5 hours 14 minutes, respectively; P <.001). There were no differences in all-cause mortality between individuals in the intervention vs control groups at 3 months (0.3% vs 0.2%, respectively; difference, 0.1%; 95% CI, −0.5% to 0.7%; P >.99) or in 3-month hospital readmission rates (4% vs 7%, respectively; P =.051). 

However, hospital admission rates were lower in the intervention group compared with the control group, at 13% and 16%, respectively (difference, 3.3%; 95% CI, 0.1%-6.6%). In addition, there were no episodes or events of hemorrhages or adverse events related to CTPA performance in either treatment group.

Researchers concluded that patients with a suspected PE at very low risk can be evaluated effectively using PERC because it was not shown to be inferior to the conventional method of identifying individuals with a PE. Further, the use of PERC was associated with less frequent use of CTPA, decreased ED length of stay, and decreased hospital admission rate.


Freund Y, Cachando M, Aubry A, et al. Effect of the pulmonary embolism rule-out criteria on subsequent thromboembolic events among low-risk emergency department patients. The PROPER randomized clinical trial. JAMA. 2018;319(6):559-566.