A Comparison Between Two Definitions of Contrast-Associated Acute Kidney Injury for Long-Term Mortality in Elderly and Non-elderly Patients After Elective Percutaneous Coronary Intervention

Abstract

Background: Contrast-associated acute kidney injury (CA-AKI) is responsible for a substantial proportion of the observed mortality that occurs after percutaneous coronary intervention (PCI), particularly in elderly patients. However, there has been significant and debate over whether the optimal definition of CA-AKI persists over prolonged periods due to variations in the prevalence and effects on prognosis. In this study, we aimed to identify whether different definitions of CA-AKI exert differential impacts on long-term mortality when compared between elderly and non-elderly patients receiving elective PCI. Methods: We prospectively investigated 5,587 consenting patients undergoing elective PCI between January 2012 and December 2018. We considered two classical definitions of CA-AKI from the European Society of Urogenital Radiology (ESUR) and the Acute Kidney Injury Network (AKIN). Multivariable Cox regression analysis was used to investigate the association between CA-AKI and long-term mortality. We also performed interaction and stratified analyses according to age (≤75 or >75 years). Results: The incidence of CA-AKI according to the ESUR and AKIN definitions was 18.7 and 6.1%, respectively. After a median follow-up of 2.1 years, multivariable Cox regression analysis indicated that CA-AKI according to the AKIN definition was a risk factor for long-term mortality in the overall population [hazard ratio (HR) = 2.20; 95% confidential interval (CI): 1.51-3.22; p < 0.001]; however, this was not the case for the ESUR definition (HR = 1.27; 95% CI: 0.92-1.76; p = 0.153). Further interaction analysis identified a significant interaction between age and the ESUR definition (p = 0.040). Stratified analyses also found an association between the ESUR definition and long-term mortality in patients >75 years of age (p = 0.011), but not in patients ≤75 years of age (p = 0.657). Conclusion: As a stringent definition of CA-AKI, the AKIN definition was significantly associated with long-term mortality in both non-elderly and elderly patients. However, in elderly patients, the more lenient definition provided by the ESUR was also significantly correlated with long-term mortality, which could sensitively identify high-risk elderly patients and may provide a better alternative.

Keywords: contrast-associated acute kidney injury; different definitions; elderly; mortality; percutaneous coronary intervention.

Figure 1

Flowchart showing the procedure used for patient recruitment. ACS, acute coronary syndrome; CAD, coronary artery disease; PCI, percutaneous coronary intervention; SCr, serum creatinine.

Figure 2

The incidence of CA-AKI according to both AKIN and ESUR definitions. CA-AKI, contrast-associated acute kidney injury; AKIN, Acute Kidney Injury Network; ESUR, European Society of Urogenital Radiology.

Figure 3

The association between the two classical definitions of CA-AKI and long-term mortality. The following parameters were adjusted: age >75 years, SCr >1.5 mg/dl, hemoglobin, multivessel disease, acute myocardial infarction, diabetes, and previous myocardial infarction. CA-AKI, contrast-associated acute kidney injury; SCr, serum creatinine; AKIN, Acute Kidney Injury Network; ESUR, European Society of Urogenital Radiology; HR, hazard ratio; CI, confidence interval.

Figure 4

Kaplan–Meier curves for long-term mortality according to the AKIN definition in the overall population (A), patients ≤75 years (B), and patients >75 years (C) and according to the ESUR definition in the overall population (D), patients ≤75 years (E), and patients >75 years (F). CA-AKI, contrast-associated acute kidney injury; AKIN, Acute Kidney Injury Network; ESUR, European Society of Urogenital Radiology.