Statistical Methods

Continuous variables are presented as mean and SD if normally distributed and compared with an unpaired t test. Categorical data are reported as a percentage and compared with the chi‐square test or Fisher exact test as appropriate. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of CI‐AKI. The 95% CIs and odds ratios (ORs) are provided in the text and tables. Variables, associated with CI‐AKI at univariate logistic regression analysis with a P<0.1, were used in the multivariate regression model.

Propensity score matching 1:1 was performed to compare CI‐AKI in patients undergoing TAVI or CA/PCI, irrespective of different baseline characteristics that may lead to biased estimates of treatment effect. The variables included in the propensity score were age, eGFR, and contrast‐medium volume. We chose these variables because they have been reported as the most relevant in the literature on CI‐AKI. 25 , 26 Propensity scores were then matched using a greedy 5‐to‐1 digit‐matching algorithm. The distribution of patient characteristics in the matched sample was compared.

A probability value of P<0.05 was considered statistically significant. All statistical analyses were performed using SPSS 20.0 (IBM, Inc., Armonk, NY).