We would like to thank Andò et al for their interest in our report. We applaud their effort to clarify the optimal threshold dose of contrast agents to prevent contrast-induced acute kidney injury (CI-AKI) and the impact of the transradial approach intervention (TRI) on the occurrence of CI-AKI.

We agree that TRI might reduce procedure-related complications including CI-AKI. In fact, TRI has been popularized from viewpoints that it is less invasive and reduces the risks of bleeding complications. From our own registry, we recently demonstrated that the frequency of TRI has been increasing over the course of the last few years and that bleeding complications have been trending downward since the implementation of TRI. Whether TRI could reduce the incidence of CI-AKI is a topic of current interest. As Ando et al quoted, accumulation of ongoing studies focused on the association between access site and the incidence of CI-AKI could facilitate a shift toward TRI, and we should pay a particular attention to their conclusions. Given the high impact of TRI-dominated percutaneous coronary intervention as mentioned earlier, we agree that recalibration for the CI-AKI risk model may be required.

For their second comment, indeed, the contrast dose was not independently associated with the incidence of CI-AKI (after the adjustment) in our study. As Andò et al noted, patients with CI-AKI are likely to have renal dysfunction at baseline, and renal function–adjusted contrast dose might be a significant predictor even in our cohort. Although identifying the threshold dose of contrast agents for each patient preprocedurally is a topic of interest, in the present study, we opted to focus on identifying the patients at risk of CI-AKI before the procedure and evaluating whether the developed preprocedural risk model has a sufficient performance compared with the conventional model. Amin et al previously demonstrated that the incidence of CI-AKI decreased from 2000 to 2008, despite the aging population and increasing prevalence of CI-AKI risk factors. These findings may reflect the increased clinical awareness, better risk stratification, and greater use of CI-AKI prevention efforts during this period. Considering that the preprocedural risk stratification had a key role in the decrease in CI-AKI incidence, developing a preprocedural risk model and demonstrating its adequate predictability was thought to be of greater relevance to bedside clinicians. If contrast doses remain varied for high-risk patients even after the awareness of the preprocedural risk of CI-AKI, further effort would be required to achieve the targeted quality indicator and improve the quality of care.