Incidence, etiologies, and outcomes of severe pediatric community-acquired empyema before and after the pandemic: an Italian multicentric study

An increase in severe and invasive infections has been reported since the COVID-19 pandemic. However, most evidence comes from monocentric studies without nationwide representativeness. This multicenter, nationwide, retrospective study, conducted within the network of the Italian Society of Pediatric Infectious Diseases (SITIP), aimed to compare the severity of empyema at presentation in children (aged 1 month to 18 years) admitted to 19 Italian hospitals before, during, and after the pandemic. A severe composite outcome was defined as either fatality, need for respiratory support or thoracic surgery, or admission to the pediatric intensive care unit (PICU). Among the 266 patients included in the study (38.7% females, median age of 4 years [IQR 2-7 years]), 95 (35.8%) were reported during the pre-COVID phase, 32 (12.1%) during the COVID phase, and 138 (52.1%) during the post-pandemic phase. The incidence of empyema significantly increased during the post-pandemic phase (pre-COVID: 95/19,288,639 [0.49]; during COVID pandemic: 32/18,784,272 [0.17]; post-pandemic: 138/18,294,627 [0.75]; p = 0.001). No differences in the demographic characteristics between the three groups were noticed, but a statistically significant difference was detected in the severe composite outcome (p = 0.029), as well as in the clinical (p = 0.006) and laboratory (p = 0.015) disease severity in children admitted during and after the pandemic. An increased odds of severe outcomes was observed during the COVID period (OR: 3.428, 95% CI: 1.21-9.65, p = 0.020) and in patients with complicated effusion observed at lung ultrasound (OR: 3.29, 95% CI: 1.26-8.57, p = 0.015). Each day of persistent fever was associated with a 10% increased risk of severe outcome (OR: 1.10, 95% CI: 1.03-1.18, p = 0.004). Since the onset of the pandemic, we observed an increased use of high flow nasal cannula. CONCLUSION: Our analysis of children admitted in Italy confirms a surge in the incidence of empyema and an increase in disease severity during and after the pandemic. WHAT IS KNOWN: • Empyema is a severe complication of pneumonia. • Some studies have suggested increase in empyemas in Europe, but no data available for Italy. WHAT IS NEW: • The incidence of empyema in Italy significantly increased during the post-pandemic phase. • An increased odds of severe outcomes was observed during the COVID period.