Statistical analysis
ARF
ARF, REGRESSION
We report the mean (standard deviation) or the median (interquartile range) for
continuous variables, while categorical variables are presented as the number
and percentage of patients. Sample size calculation was based on the expected
difference in the ARF rate between the MI-E and control groups 48 hours after
extubation. We considered the initial risk of ARF 48 hours after extubation in
the control group to be 30% (a usual finding in our ICU). This reflected our
hypothesis of a 50% relative decrease in ARF in the intervention group, as we
informed the statistician that we expected a very high impact of MI-E as an
adjunctive treatment, according to our clinical experience. With a 5% bilateral
α risk, we needed to enroll 240 participants (120 per group) to achieve
80% power in an intent-to-treat analysis. Missing data for the primary outcome
were considered failures. An independent scientific committee validated each
exclusion.Nominal variables were compared by using the Chi-square test or Fisher’s exact
test, as appropriate. Continuous variables were compared by using Student’s t
test or the Wilcoxon signed rank test, when appropriate. Adjusted analyses were
performed considering available data and using logistic regression models.Survival analyses were performed using the log-rank test and expressed by
Kaplan‒Meier curves. Semiparametric Cox regression models were used to perform
adjusted analyses. Statistical analyses were implemented in SAS® Software
(SAS v9.3, SAS Institute Inc., Cary, NC, USA). For all performed comparisons, a
p value of ≤ 0.05 was considered statistically significant.