Safety of the Combination of PERC and YEARS Rules in Patients With Low Clinical Probability of Pulmonary Embolism: A Retrospective Analysis of Two Large European Cohorts

Background This study aimed to determine the failure rate of a combination of the PERC and the YEARS rules for the diagnosis of pulmonary embolism ( PE ) in the emergency department ( ED ). Methods We performed a retrospective analysis of two European cohorts of emergency patients with low gestalt clinical probability of PE ( PROPER and PERCEPIC ). All patients we included were managed using a conventional strategy (D‐dimer test, followed, if positive, by computed tomographic pulmonary angiogram ( CTPA ). We tested a diagnostic strategy that combined PERC and YEARS to rule out PE . The primary endpoint was a thromboembolic event diagnosed in the ED or at 3‐months follow‐up. Secondary endpoints included a thromboembolic event at baseline in the ED and a CTPA in the ED . Ninety‐five percent confidence intervals ( CI s) of proportions were calculated with the use of Wilson's continuity correction. Results We analyzed 1,951 patients (mean ±  SD age = 47 ± 18 years, 56% women) with an overall proportion of patients with PE of 3.5%. Both PERC and YEARS strategies were associated with 11 missed PE in the ED : failure rate 0.57 (95% CI  = 0.32–1.02). At 3‐month follow‐up, the overall failure rate was 0.83% (95% CI  = 0.51–1.35). Among the 503 patients who underwent a CTPA (26%), the use of the PERC – YEARS combination would have ruled out PE without CTPA in 249 patients (50% [95% CI  = 45%–54%], absolute reduction 13% (95% CI  = 11%–14%]). Conclusion The combination of PERC then YEARS was associated with a low risk of PE diagnostic failure and would have resulted in a relative reduction of almost half of CTPA .