Statistical analysis
BPD, death
REGRESSION
Clinical characteristics of infants in the CG and LUSG will be described using mean values and standard deviation, median and interquartile range, or rate and percentage. Univariate statistical analysis will be performed using the Student’s Subsequently, clinical characteristics which are most likely associated with BPD or death will be included in a multiple logistic regression analysis to assess their independent role in predicting clinical outcome. Effect estimates will be expressed as odds ratios (ORs) with maximum likelihood-based 95% confidence limits.The primary statistical analyses will be performed according to the intention-to-treat principle. The per-protocol analyses will be also performed with an explanatory intent. Major protocol deviations will be reported. Patients without any information available about the primary study endpoint will be classified as failure. Single imputation will be used in case of missing values will be observed for the covariates included in the adjusted and subgroup analyses.