Statistical analysis
Measurement data are reported as the mean ± standard deviation. The analysis used a random effects model (inverse-variance method). For short term categorical outcomes, risk difference with 95% confidence interval were used, as many studies have zero events in both sides. For continuous outcomes, standardized mean difference (SMD) and 95%CI were used. For late outcomes, incidence rate ratio and 95%CI were estimated from the total number of events observed within a treatment group out of the total person-time of follow-up for that treatment group8. Meta-regression was used to assess the effect of sample size, age, gender, chronic obstructive pulmonary disease, New York Heart Association (NYHA), previous stroke/transient ischemic attack (TIA) and redo surgery on the primary outcomes and secondary outcome (perioperative mortality).
Hypothesis testing for equivalence was set at the 2-tailed 0.05 level. Analyses and data modeling were performed with R-project (version 3.3.3 R project for Statistical Computing), following packages were used: ‘metafor’, ‘stats’, and ‘graphics’ for data visualization.
.