Statistical analysis
Statistical analysis was performed using the SPSS statistical software
v. 25.0 (IBM Corporation, Armonk, NY, USA), and Stata v. 15.1 (StataCorp
LLC, College Station, Texas, USA). Covariates and outcomes were reported
as counts and percentages, and as mean and standard deviation or median
and interquartile range (IQR). The Kruskal-Wallis test and the
linear-by-linear association test were used for univariate analysis. The
risk-adjusted mortality rates over different VA-ECMO interval durations
were estimated using the direct standardization method employing thedstdize module of Stata, and the patient population were
stratified according to different duration of VA-ECMO therapy: ≤3 days,
4-7 days, 8-10 days, and >10 days [3,7]. The impact of
VA-ECMO duration on hospital mortality was also adjusted for the PC-ECMO
score [4], multiple covariates and participating centers in logistic
regression analysis. A P < .05 was set for statistical
significance.