Hospitalizations for respiratory syncytial virus (RSV) in Sicily from 2008 to 2021: clinical features and predictors of severity.

Background: Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis, resulting in 3.6 million hospitalizations for acute lower respiratory tract infections and 101,400 deaths in children under 5 years of age worldwide each year. In Europe, the estimated incidence of RSV-related hospitalizations in infants is 1.8%. We describe the incidence of RSV infection in patients hospitalized in Sicily (Italy) between 2008 and 2021, examine the clinical-epidemiological characteristics of RSV-positive patients, and assess comorbidities associated with illness severity.

Methods: All data were retrospectively collected from standard hospital discharge records (HDRs). Significant factors from the univariate analysis were included in a multivariate logistic regression using the stepwise forward selection method to calculate adjusted odds ratios (aORs) and identify independent risk factors for ICU admission.

Results: Collectively, within the study time frame, 4,485 hospital admissions were RSV-related, 271 patients (6%) were admitted to the ICU, and eight deceased (0.2%). The majority of hospitalized patients (86%) were infants (up to 1 year old), 16.5% were newborns (<28 days), and 10.1% were in the 1-4-year-old group. Several predictors of ICU admission, including neonatal sepsis, neonatal respiratory distress, and younger age (in months), were identified through multivariate logistic regression analysis.

Conclusions: RSV-associated pathologies are important causes of hospitalization in Sicily, and young age (particularly 0-3 months) and comorbidities, including nutritional and metabolic disorders (with a stronger effect in the pediatric subgroup) and congenital heart diseases, are important outcome predictors. However, considering that RSV-related diseases continue to require hospitalizations in healthy children and adults, it is important to continue monitoring RSV-related hospitalizations through updated epidemiological studies, which can guide the implementation of existing preventive strategies and inform the cost‒benefit analysis of new ones.