[Analysis of respiratory syncytial virus infection status and factors associated with severity in hospitalized preterm infants under 5 years of age].

This study aimed to investigate the clinical characteristics of respiratory syncytial virus-associated acute lower respiratory tract infection (RSV-ALRI) in hospitalized preterm infants and to analyze factors associated with severe RSV-ALRI, so as to provide evidence for early identification of high-risk infants and formulation of precise intervention strategies. A cross-sectional study was conducted, enrolling preterm infants under 5 years of age with RSV-ALRI who were admitted to the Department of Pediatrics at the Women's Hospital of Nanjing Medical University between July 1, 2023, and June 30, 2025. Birth data, clinical information, and pathogen test results were collected. According to the severity criteria specified in the Diagnostic and Treatment Guidelines for Community-Acquired Pneumonia in Children (2019 Edition) and the Clinical Practice Guidelines for the Management of Bronchiolitis in Children (2024 Edition), combined with the patients' clinical manifestations during hospitalization, the infants were divided into a mild-to-moderate group and a severe group. Multivariable logistic regression was used to analyze factors associated with severe RSV-ALRI. A total of 91 subjects were included, among whom infants aged <3 months and 3∼<6 months accounted for 27 (29.67%) and 22 (24.18%), respectively, and 71.43% of cases occurred within the first year of life. RSV-A subtype was detected in 23 cases (25.27%) and RSV-B subtype in 68 cases (74.73%). Co-detection of other pathogens was observed in 79 cases (86.81%), among which Acinetobacter baumannii (30 cases, 32.97%) and cytomegalovirus (27 cases, 29.67%) were the most common. Respiratory symptoms predominated in RSV-ALRI patients, including cough in 90 cases (98.90%), laryngeal rales in 88 cases (96.70%), rhinorrhea in 48 cases (52.75%), wheezing in 47 cases (51.65%), and nasal congestion in 47 cases (51.65%). Multivariate logistic regression analysis revealed that onset age <6months was an associated factor for severe RSV-ALRI in preterm infants (OR=34.71, 95%CI: 6.57-183.41, P<0.001); higher gestational age at birth was associated with lower likelihood of severe RSV-ALRI (OR=0.75, 95%CI: 0.57-1.00, P=0.049).