2.3. Statistical analysis
Data for the outcomes of interest are presented in numbers and percentages and mean values with a 95% confidence interval (CI) were also considered. The measurement of the weighted prevalence of outcomes was performed and is presented in forest plots. Moreover, the conversion of the median for continuous values (e.g., age and length of stay) into the mean was applied as needed. Furthermore, the I2 statistic was used to quantify the total variability among eligible studies, ascribable to heterogeneity, and reported in percentages with a 95% CI. The I2 covers the spectrum of 0% indicating no heterogeneity, 25% to 49% as low heterogeneity, 50% to 74% as moderate heterogeneity, and ≥75% as high heterogeneity, according to published guidelines [13, 14]. The random-effects model, where the I2 value lies above 50%, was utilized, and a fixed-effects model (Mantel – Haenszel method) was used when significant heterogeneity was absent. Regarding the inconsistency among some of the results of observational studies including stent type (Thoraflex Hybrid, E-Vita, Cronus, Frozenix, and mixed/other), location of the study center (Asia, North America, and Europe), and elective/non-elective procedure, subgroup analyses were performed. Publication bias was evaluated by Egger’s test and visualized by the funnel plots, and additionally, statistical tests for its asymmetry were employed. The statistical significance was reached by P-values below 0.05. All the statistical analyses were performed using R (version 4.1.2) and STATA (V.16.0) softwares.