2.2 Data collection
We included all children aged 0-2 years with an ICD-9 diagnosis of
bronchiolitis from September 2017 to August 2023. We considered each
epidemic year beginning on September 1 and lasting until August 31 of
the following year.
Admissions between May 1 and September 30 of each year were also
identified as “out-of-season cases”.
Demographic, microbiological, clinical, and outcome data were collected.
The need, type,
and duration of respiratory support (low-flow oxygen, high-flow nasal
cannula, C-PAP, MV) were also recorded.
To compare frequencies between cohorts, all modalities have been lumped
into a single ”respiratory support” variable.
Identification of the causal viral agent was carried out using a
nasopharyngeal swab with a
multiplex polymerase chain reaction (PCR) assay. A SARS-CoV-2 antigen or
molecular test was performed at admission to the Emergency Department
(ED) in all patients with
respiratory symptoms from February 20th, 2020.