Association of Systolic and Diastolic Blood Pressure with the Risk of End-Stage Renal Disease in Older Type 2 Diabetes Mellitus Patients without Cardiovascular Disease: A Nationwide Population-Based Study (Diabetes Metab J 2025;49:1308-17)
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We sincerely appreciate the thoughtful and constructive comments from Wang and Shao regarding our recently published article [1]. Their insights regarding the proportional hazards (PH) assumption and the treatment of competing risks provide an important opportunity to further clarify and strengthen the methodological rigor of our analysis. Below, we address each concern in detail.
We fully agree with the authors on the importance of the PH assumption in Cox regression models. Although we did not explicitly detail the diagnostic procedures in the final manuscript for the sake of brevity, we did assess the PH assumption during our preliminary analysis. We utilized both log-minus-log plots and Schoenfeld residuals to check for any violation of the assumption. Our diagnostic checks did not reveal substantial deviations that would invalidate the reported estimates. We apologize for the omission of these details in the published text and appreciate the authors pointing out the need for this transparency.
The authors correctly pointed out that in an elderly population with type 2 diabetes mellitus, death acts as a significant competing risk for end-stage renal disease (ESRD). We acknowledge that standard Kaplan-Meier estimates may overestimate the cumulative incidence of the event of interest in the presence of competing risks.
However, as discussed in previous literature [2,3], there is a distinct difference in the interpretation and utility of the standard Cox model and the Fine-Gray model. The cause-specific hazard model (standard Cox) is generally preferred for addressing etiological questions, as it estimates the instantaneous rate of event occurrence among subjects who are currently event-free [2,4]. In contrast, the Fine-Gray model (subdistribution hazard) is better suited for estimating absolute risk and clinical prognosis [2]. Since our study aimed to investigate the direct biological association between blood pressure components and the development of ESRD rather than to build a predictive model for absolute risk, we believe the cause-specific hazard approach remains methodologically valid for our research question.
Unfortunately, conducting a post hoc analysis using the Fine-Gray model is not feasible at this stage due to data access limitations. Nevertheless, we fully accept the authors’ constructive suggestion as a limitation of our study. Future research involving this high-risk geriatric population should certainly incorporate competing risk analyses to provide a more comprehensive perspective on absolute risk.
We hope this response adequately addresses the concerns raised and clarifies our methodological stance.
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CONFLICTS OF INTEREST
Sung Hoon Yu has been an associate editor of the Diabetes & Metabolism Journal since 2022. He was not involved in the review process of this article. Otherwise, there was no conflict of interest.
ACKNOWLEDGMENTS
The National Health Information Database is maintained by the National Health Insurance Service of Korea. The authors would like to thank the National Health Insurance Service for their cooperation.