2.1-Study design, sites, and subjects
We performed a single-center retrospective study of children under five
years of age hospitalized with a clinical diagnosis of LRTI, presenting
to the emergency department, outpatient clinics (pediatric pulmonology,
pediatrics, pediatric infectious disease), or ICU of Ege University
Medical Faculty Children Hospital from January 2010 through January
2020. The hospital institutional review board approved this study.
The study institution’s standard practice is to screen all admitted
patients with respiratory symptoms for viral respiratory pathogens.
Because the International Classification of Diseases discharge codes
might be inaccurate coding or misdiagnosis on the part of the treating
clinician, cases were identified by evaluating the virology laboratory
database. Subsequently, we cross-checked the virology laboratory results
with electronic medical records and nurse observation charts. According
to the revised World Health Organization guidelines11,
patients between 1-60 months of age who clinically fulfilled the
criteria of LRTI (pneumonia or bronchiolitis) were included in the
study. Exclusion criteria included hospitalization within the preceding
30 days, other diagnoses than LRTI caused by respiratory viruses,
hospital-acquired viral LRTI, primary (defined as bacterial growth
detected in cultures from sterile cavities such as blood, cerebrospinal
fluid, urine, and pleural fluid) or secondary (defined as bacterial
growth in cultures taken from sterile cavities 48 hours after
hospitalization)12 bacterial infections, newborns
(under one month of age), and incomplete medical records.