Abstract: BackgroundBackground:Community-acquired pneumonia (CAP) is a common disease in children. When it progresses to severe pneumonia, it imposes a heavy disease burden, necessitating early identification and intervention. ObjectiveTo explore the epidemiological characteristics and risk factors for children with severe pneumonia in Shanghai. DesignA cross-sectional survey. MethodsClinical data of pediatric CAP cases hospitalized in Shanghai from January 1, 2018, to June 30, 2022, were collected through the Shanghai Pediatric Clinical Quality Control Center (SPQCC) data management platform. The study population was divided into a severe pneumonia group and a non-severe pneumonia group, with the severe pneumonia group further divided into pre-COVID-19 and during-COVID-19 subgroups. The clinical characteristics of severe and non-severe pneumonia cases were compared, changes in severe CAP characteristics before and during the pandemic were analyzed, and the risk factors for severe CAP were explored. Main outcome measuresThe risk factors for severe pneumonia. ResultsAmong the 81,526 CAP cases included in this study, 43,792 (53.7%) were male, with an average age of 4.0±2.8 years. Preschool-aged children accounted for the largest proportion (40.2%). A total of 11,686 cases (14.3%) were classified as severe pneumonia, with incidence rates showing an increasing trend since 2020. The proportion of severe pneumonia cases was higher among infants and toddlers compared to other age groups, higher in males than females, higher during the COVID-19 pandemic than before, higher in winter compared to other seasons, and higher in children with underlying conditions such as airway developmental abnormalities, congenital heart disease, neuromuscular diseases, genetic syndromes, and malnutrition (all P<0.01). Compared with the non-severe pneumonia group, children with severe pneumonia had significantly longer hospital stays, higher hospitalization costs, and a higher incidence of adverse outcomes (all P<0.05). During the COVID-19 pandemic, the proportion of severe pneumonia cases seeking medical care at specialized hospitals and being admitted through the emergency department increased, while the proportion of non-Shanghai residents decreased. The incidence of complications, including acute respiratory failure, pneumothorax, liver dysfunction, sepsis, and septic shock, was higher in the pandemic subgroup than in the pre-pandemic subgroup, with higher hospitalization costs and longer hospital stays (all P<0.05). Among children with severe pneumonia, infants and young children had a higher likelihood of undergoing extracorporeal membrane oxygenation (ECMO) and mechanical ventilation, whereas ≥3 years old children were more likely to undergo thoracentesis, bronchoscopy, and alveolar lavage. Independent risk factors for progression to severe pneumonia included infancy, male sex, the COVID-19 pandemic, winter season, and comorbidities such as airway developmental abnormalities, congenital heart disease, neuromuscular diseases, genetic syndromes, and malnutrition. ConclusionYoung age, male sex, the COVID-19 pandemic, winter onset, and certain comorbidities were identified as independent risk factors for severe pneumonia in children. In clinical practice, early identification of severe pneumonia cases is crucial for timely intervention.

Key words: Community-acquired pneumonia, Epidemiology, Severe pneumonia, Risk factor