Comparison of Thrombotic Events and Mortality in Patients with Community-Acquired Pneumonia and COVID-19: A Multicenter Observational Study.

Background: It is still unclear if patients with community-acquired pneumonia (CAP) and coronavirus disease 2019 (COVID-19) have different rate, typology, and impact of thrombosis on survival.

Methods: In this multicenter observational cohort study, 1,138 patients, hospitalized for CAP ( = 559) or COVID-19 ( = 579) from seven clinical centers in Italy, were included in the study. Consecutive adult patients (age ≥ 18 years) with confirmed COVID-19-related pneumonia, with or without mechanical ventilation, hospitalized from March 1, 2020 to April 30, 2020, were enrolled. COVID-19 was diagnosed based on the World Health Organization interim guidance. Patients were followed-up until discharge or in-hospital death, registering the occurrence of thrombotic events including ischemic/embolic events.

Results: During the in-hospital stay, 11.4% of CAP and 15.5% of COVID-19 patients experienced thrombotic events ( = 0.046). In CAP patients all the events were arterial thromboses, while in COVID-19 patients 8.3% were venous and 7.2% arterial thromboses.During the in-hospital follow-up, 3% of CAP patients and 17% of COVID-19 patients died ( < 0.001). The highest mortality rate was found among COVID-19 patients with thrombotic events (47.6 vs. 13.4% in thrombotic-event-free patients;  < 0.001). In CAP, 13.8% of patients experiencing thrombotic events died versus 1.8% of thrombotic event-free ones ( < 0.001). A multivariable Cox-regression analysis confirmed a higher risk of death in COVID-19 patients with thrombotic events (hazard ratio: 2.1; 95% confidence interval: 1.4-3.3;  < 0.001).

Conclusion: Compared with CAP, COVID-19 is characterized by a higher burden of thrombotic events, different thrombosis typology and higher risk of thrombosis-related in-hospital mortality.