Safety of the 4PEPS in Patients With a Very Low Prevalence of Pulmonary Embolism—Need for More Than a Point Estimate

To the Editor We read with great interest the article by Roy et al¹ describing a new 4-Level Pulmonary Embolism Clinical Probability Score (4PEPS) to rule out pulmonary embolism (PE). As recommended by the Scientific and Standardization Committee of the International Society of Thrombosis and Hemostasis,² the authors predefined the acceptable upper limits of the 95% CI of failure rate at 1.93% and 1.88% for their 2 external validation cohorts. The authors found the failure rates and 95% CI of the 4PEPS below these predefined limits and concluded that the safety of the 4PEPS strategy was confirmed.