MATERIALS AND METHODS
The data source of this retrospective study was the National Inpatient Sample (NIS) data registry that consisted of a complete set of background, intra-operative, and postoperative information of the patients undergoing PCI procedures. The collected information included demographic characteristics, underlying cardiac risk factors, laboratory findings at the time of admission, characteristics related to coronary artery involvement, such as the severity of involvement and the number of coronary arteries under the procedure, and intra- and postoperative outcomes during hospitalization. Patients were classified into two groups with ACKD and without this co-morbidity. The in-patient death defined as death that occurred postoperatively during hospitalization was the parameter of interest.
The Kolmogorov-Smirnov test was primarily used to assess the normality states of the study variables. The Chi-square test was applied to determine the statistical differences between categorical parameters, while the t-test or Mann-Whitney U test was employed to assess the difference between quantitative variables. To determine the values of chronic renal failure to predict in-hospital death following PCI, the multivariate logistic regression analysis was used with the presence of baseline variables. P values of ≤ 0.05 were considered significant. The statistical software SPSS version 28.0 for Windows (IBM, Armonk, New York) was used for statistical analyses.