Burden, risk factors, and outcomes respiratory syncytial virus (RSV) infection in pediatric intensive care units in Türkiye (RSVP Study 2020-2024)

Background: Respiratory syncytial virus (RSV) is one of the leading causes of respiratory tract infections in infants and young children requiring a pediatric intensive care unit (PICU). This study aimed to characterize the clinical features, complications, co-infections, and risk factors associated with RSV-related morbidity and mortality in a large PICU cohort over five years. Methods: This is a retrospective multicenter study to evaluate medical records of patients with RSV infection admitted to the PICUs in Türkiye between 2020 and 2024, including the COVID-19 pandemic. Clinical data, co-morbidities, complications, and outcomes were analyzed. Logistic regression was performed to identify factors associated with mortality. Results: During the study period, medical records of 646 children (360 boys, 286 girls, 70% younger than 12 months; 70.6% previously healthy) were evaluated. Of the total, 388 patients were delivered by cesarean section, and 139 were born preterm (21.5%; mean gestational age: 32.9 ± 2.96 weeks). A history of newborn intensive care unit admission was present in 174 cases (26.9%). Underlying disease was identified in 190 children (29.4%), and congenital heart disease in 58 (9.0%). Most of them had pneumonia (59.8%) or bronchiolitis (38.1%). Complications included pleural effusion (n = 8), pneumothorax (n = 8), central nervous system involvement (n = 19), apnea (n = 10), and myocarditis (n = 5). Pediatric Acute Respiratory Distress Syndrome (pARDS) occurred in 82 patients (12.7%) and eight pARDS cases (9.8%) resulted in death. The number of pARDS admissions was low during the initial phase of the pandemic, and we observed a resurgence in 2022–2024, peaking in November-December every year. Respiratory co-pathogens were detected in 169 patients (26.2%). The most frequent viral co-infections were rhinovirus/enterovirus (n = 57), influenza A (n = 23), coronavirus NL63/OC43/HKU (n = 17), adenovirus (n = 15), and SARS-CoV-2 (n = 12). Bacterial and fungal secondary infections were identified in 49 patients, most commonly Streptococcus pneumoniae (n = 10) and Pseudomonas aeruginosa (n = 10). During PICU admission, 381 patients required high-flow nasal cannula, 57 non-invasive ventilation, and 106 invasive mechanical ventilation (IMV). Over the clinical course, 165 patients (25.5%) required IMV. The median PICU stay was 6 days. Overall mortality rate was 5.4%, mainly in children with the presence of underlying conditions. Logistic regression revealed that the presence of an underlying disease significantly increased mortality risk (OR 3.15, p < 0.01) and this association remained significant in infants under one year (OR 3.57, p < 0.01). Conclusion: Most children admitted to the PICU due to RSV infection were under one year of age and previously healthy, while mortality was associated with underlying conditions. pARDS is an important clinical picture in the PICU. Secondary infections are common and may complicate disease progression. Monitoring RSV cases in the PICU can be used as a probe for determining the burden of disease and economic cost in the country and for potential treatment and prevention strategies.