Background: There is an alarming trend toward overuse of computed tomographic pulmonary angiography (CTPA) for the rule-out of low clinical probability PE. The eight-item Pulmonary Embolism Rule-Out Criteria (PERC) rule was devised to be used in populations of patients with low clinical probability of PE to guide which patients would likely not benefit from CTPA imaging. Recent concerns have been raised that the use of the PERC rule could result in high false-negative rates.
Study design: Crossover cluster–randomized clinical noninferiority trial.
Setting: 14 EDs in France from August 2015 to September 2016.
Synopsis: 1,916 emergency department patients with low clinical probability of PE were cluster-randomized to usual care or to a PERC strategy where, if the PERC score was zero, PE was ruled out without additional testing. The primary outcome was diagnosis of a symptomatic PE within 3 months that had not been diagnosed initially. Primary outcome results met prespecified noninferiority criteria for the PERC group, compared with the usual-care group (0.1% in the PERC group, 0% in the control group). The PERC group had significantly lower median length of ED stay and lower likelihood of admission.
Limitations of this study include its younger average patient age (44 years) and its cluster, as opposed to per-patient, randomization design.
Bottom line: In patients for whom the clinical probability of PE is low, use of the PERC rule is noninferior to a conventional d-dimer and CTPA strategy for ruling out symptomatic PE.
Citation: Freund Y et al. Effect of the pulmonary embolism rule-out criteria on subsequent thromboembolic events among low-risk emergency department patients. JAMA. 2018;319(6):559-66.
Dr. Abdallah is a hospitalist at Beth Israel Deaconess Medical Center, and instructor in medicine, Harvard Medical School, Boston.