Kong T, et al. - Authors probed the clinical usefulness of the delta neutrophil index (DNI) as a marker of severity in patients with acute pulmonary embolism (PE) admitted to the Emergency Department (ED). They retrospectively evaluated the data of patients who were diagnosed with acute PE at a single ED, admitted from January 1, 2011 to June 30, 2017. Findings suggested that it was easy to determine the DNI value, obtained as part of the complete blood count analysis without additional burdens of cost or time. In patients with acute PE, a high DNI was useful as a marker to predict 28-day mortality.