Comparison of thrombotic events and mortality in patients with community-acquired pneumonia and COVID-19: a multicentre 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 multicentre observational cohort study 1.138 patients, hospitalized for CAP (n=559) or COVID-19 (n=579) from 7 clinical centres 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 1st March 2020 to 30 April 2020, were enrolled. Covid-19 was diagnosed based on the WHO 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 (p=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 (p<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; p<0.001). In CAP, 13.8% of patients experiencing thrombotic events died vs. 1.8% of thrombotic event-free ones (p<0.001). A multivariable COX-regression analysis confirmed a higher risk of death in COVID-19 patients with thrombotic events (HR 2.1; 95% CI: 1.4-3.3; p<0.001). Conclusions: 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.