Statistical analysis
SECONDARY
We assumed a between-group median difference of 25% in hospital LOS as clinically significant. To detect this difference with a two-sided α error of < 0.05 and a After checking the normality assumption for the baseline summary statistics, continuous data are presented as mean (standard deviation) or median (interquartile range) where appropriate. Categorical data are expressed as number (proportion). Then, the balance between the study groups were evaluated with the generalized estimating equations procedure accounting for intra-cluster correlation [The primary clinical outcome, hospital LOS after OPCAB, was estimated using the cumulative incidence function plot and compared between the groups using the Fine and Gray model to adjust for the month-by-month clustered data and account for competing risk of in-hospital mortality.For analyses of the exploratory secondary clinical and biochemical outcomes, the generalized estimating equations procedure was used, accounting for intra-cluster correlation [Data were analyzed using SAS (version 9.4; SAS Institute, Cary, NC, USA) or R (version 4.1.2; R Foundation for Statistical Computing, Vienna, Austria). A two-tailed 