The PESI is a validated prognostic score for patients with acute PE and comprises 11 easily available clinical variables, including patient demographics, comorbid diseases, and vital signs . Based on patient demographics and the first available baseline clinical data obtained by chart review, we determined the presence of the prognostic variables comprising the PESI. Whenever necessary, missing values were assumed to be normal. This strategy is widely used in the clinical application of prognostic models and reflects the methods used in the original derivation of the PESI [4, 27].