Statistical analysis: All relevant clinical parameters will be analysed by frequencies, tabulations, correlations, distributions of normality and comparisons accordingly. An array of statistical methods will be employed for parametric and non-parametric data including Multivariate of all factors associated with the development of acute kidney injury following cardiac surgery. Receiver operator characteristic (ROC) curve analysis will be used to investigate clinical outcomes and the new markers of cell senescence (telomere length, telomerase activity, and DNA methylation status). Missing data values will be rectified where possible by review of the primary medical records. Missing data values due to incomplete sample collection will be dealt with by statistical modelling.