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More Evidence that PERC Works!

June 30, 2023

Written by Christian Gerhart

Spoon Feed
Among patients in the RIETE database with confirmed pulmonary embolism (PE), there was a low failure rate when pulmonary embolism rule-out criteria (PERC) was applied in this retrospective cohort. PERC-negative patients who had PE were less likely to have proximal PE, and their rates of cardiopulmonary complications were lower when compared to PERC-positive patients.

Why does this matter?
The PERC tool is used in Emergency Departments around the world to risk stratify patients who may have acute PE. Although the PERC rule is endorsed by the American College of Emergency Physicians to exclude PE in low-risk patients (Level B recommendation), there remains some controversy regarding its safety in populations with high prevalence of PE. This study sought to evaluate the safety of the PERC rule using a large, international registry of patients with confirmed PE in the ED setting.

PERC worked!
This was a retrospective cohort study using 20 years of data from 48,903 patients from the RIETE database. Authors determined, as well as they could by retrospective registry review, whether the patient would have been PERC negative or PERC positive on their initial ED evaluation. Out of the 48,903 patients with confirmed PEs, only 346, or 0.7% (95%CI 0.6-0.8%) were PERC negative. Compared to PERC positive patients, PERC negative patients were less likely to have main pulmonary artery emboli (11% vs. 22%, p<0.001) and less likely to have right ventricular hypokinesis if an echocardiogram was performed (13% vs. 23%, p<0.05). When the Pulmonary Embolism Severity Index (PESI) score was applied (a tool estimating 30-day mortality in PE), PERC negative patients were more likely to have a score ≤65 indicating a very low mortality compared to PERC positive patients (86% vs. 16%, p<0.001).

It seems that reliably extracting clinical gestalt, unilateral leg swelling, or hemoptysis retrospectively would be difficult. Despite this limitation, this study provides further evidence that additional testing can be safely avoided in PERC-negative patients.

Peer reviewed and edited by Bo Stubblefield and Clay Smith

Another Spoonful
Check out these recent articles reviewing diagnostic algorithms in acute PE: Freund, et al. in JAMA and Kahn, et al. in NEJM.

Safety of the pulmonary embolism rule-out criteria rule: Findings from the Registro Informatizado de la Enfermedad TromboEmbolica venosa (RIETE) registry. Acad Emerg Med. 2023 Apr 24. doi: 10.1111/acem.14744. Epub ahead of print.

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