Statistics
REGRESSION, SECONDARY, COMPLICATION
The statistical analysis plan for the study involves various tests and methods to analyze different endpoints. The chi-squared test will be applied to compare the perioperative 120-day mortality between the control and intervention arms using an intent-to-treat analysis. The significance levels were set to 5% (two-sided). The secondary endpoints will each be analyzed accordingly: The rate of primary anastomoses, permanent stomas, and 120-day complication rate will be investigated using the chi-square test. The 3-year overall survival will be examined using the Kaplan-Meyer estimator combined with the log-rank test. The treatment effect on the patient-reported quality of life will be analyzed using a regression analysis. Quality-adjusted survival will be analyzed using marginal models and non-parametric regression.The statistical significance of stratification factors will be assessed. Propensity score matching may be used as a part of a supplementary analysis, to control for potential confounding factors that were not accounted for during sampling. In particular, a propensity score matching procedure with age as a continuous variable may be used to control for between-arm age differences. Statistical analyses of matched-sub-cohorts will have an exploratory character, providing additional information about effect sizes. The standardized mean differences and confidence intervals will be reported, and 