Statistical Analysis
comorbidity
Statistical analysis was performed according to the intention-to-treat approach, considering all enrolled patients until discharge. The time to reach FEF was computed as number of days from randomization to FEF achievement and was estimated with the Kaplan-Meier method. Infants who were transferred or died before reaching FEF or whose parents had revoked consent were censored. Secondary nutritional outcomes, growth, respiratory outcomes, comorbidity, and length of hospital stay were analyzed using appropriate models and tests (eTable 4 in A sample size of 123 infants per group was estimated to achieve 90% power to detect a difference of 30% on the primary outcome of time to reach FEF (which was projected to be 19.6 days based on data from the participating NICUs the year before the trial started) using a 2-sided log-rank test with a significance level of 