Clinical characteristics and in-hospital outcomes associated with RSV-ALRI compared to other viral ALRI in hospitalised children under two years old.

Background: Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory infections (ALRIs) associated hospitalisations in children. It is unclear if hospitalized RSV-ALRI differs in clinically from other viral ALRIs. We aimed to compare the disease impact of hospitalised RSV with other viral ALRI in children under 2 years.

Methods: We conducted a retrospective study using electronic medical records of children under 2 hospitalized with ALRIs at Sydney Children's Hospitals Network from 2020-2022. We compared demographics and clinical features between RSV-positive and RSV-negative (positive for other viruses) cases. Poisson quasi-likelihood regression was used to estimate adjusted prevalence ratios (aPRs) for three in-hospital outcomes: length of stay, need for respiratory support and intensive care.

Results: We examined 330 children under 2 years hospitalized with RSV-positive ALRIs and 330 with RSV-negative ALRIs (positive for other viruses). RSV-positive cases were older (12 vs. 8 months, p<0.001) and more often presented with cough (99% vs. 92%), fever (80% vs. 58%), crackles (89% vs. 76%), hypoxia (50% vs. 36%), and lethargy (36% vs. 20%). They were also more likely to undergo chest x-rays (74% vs. 49%) and receive antibiotics (65% vs. 35%). Adjusted analysis showed RSV-positive children had a higher likelihood of LOS > 2 days (aPR 1.95, 95% CI 1.14-3.36).). However, there were no differences in the need for intensive care or respiratory support.

Conclusion: Children with RSV-ALRI exhibited more severe symptoms, received more antibiotics, and had longer hospital stays compared to those with other viral ALRIs, underscoring the need for effective prevention and treatment strategies for RSV.