2.3 Statistical analysis
For the study, we compared the bronchiolitis admissions of the 2022-2023 season with the previous five seasons.
Descriptive statistics were produced for demographic and clinical features. Mean and
standard deviation (SD) are presented for normally distributed variables; median and
interquartile range (IQR) for non-normally distributed variables. Numbers and percentages
are presented for categorical variables.
Differences in the frequency of categorical variables were assessed by chi-square or
Fisher’s exact tests. Continuous variables were assessed by U-Mann Whitney or Kruskal
Wallis tests where appropriate.
To assess the trend of bronchiolitis episodes across seasons, incidence (calculated as the
number of bronchiolitis per 1000 hospitalizations) was evaluated over the study years. On the other hand, the need for respiratory support was calculated as rate*100 bronchiolitis.
Pearson’s (or Spearman rho where appropriate) correlation coefficient was calculated to define whether the difference in the incidence of bronchiolitis, respiratory support, and HFNC use was merely apparent.
This study was conducted in accordance with the Helsinki Declaration. According to Italian
legislation, the study did not need ethical approval, as it was a purely observational retrospective study on routinely collected anonymous data. Furthermore, it was not possible to request informed consent for participation in the study, given the nature of the study. In any case, consent to completely anonymous use of clinical data for research/epidemiological purposes is requested during clinical routine at the time of admission/diagnostic procedure.
3. Results :