Abstract
Introduction: We evaluated the association between iron-related biomarkers – key indicators of iron metabolism and inflammation, and crucial in the management of anemia in patients undergoing hemodialysis – and all-cause mortality. This study aimed to clarify the nuanced relationship between these biomarkers and mortality outcomes, addressing the limitations of traditional cutoff-based analyses. Methods: We conducted a cohort analysis of patients undergoing dialysis across Japan using data from the Japan Renal Database collected between 2019 and 2020. Patients who had been on dialysis for at least 3 months by the end of 2019 were considered eligible. The associations between iron-related biomarkers and all-cause within 1 year were analyzed using Cox proportional hazards models. The relationship between each biomarker and outcome was illustrated using restricted cubic spline curves, while the combined association of serum ferritin and transferrin saturation (TSAT) with mortality was shown using contour plots. Results: A total of 215,927 patients were included in the analysis. During the follow-up period, 17,803 (8.24%) deaths were recorded. Contour plots demonstrated increased mortality risk in areas with low ferritin and TSAT levels. Additionally, even in regions with high TSAT levels, there was a trend toward increased mortality risk with increasing ferritin levels. Conversely, in areas with low ferritin levels, there was a trend toward a decreased risk of death with increasing TSAT. Conclusions: Our findings highlight the complex interplay between serum ferritin and TSAT levels, emphasizing the limitations of relying on single cutoff values for clinical decision-making. The study underscores the need for individualized approaches to iron management in patients undergoing hemodialysis.
Plain Language Summary
In this study, we looked at how certain iron-related blood measures, including ferritin and transferrin saturation (TSAT), are linked to death risk in Japanese people on dialysis. Ferritin and TSAT levels can vary widely, and understanding their impact on health can help guide better treatment decisions. We followed over 215,000 dialysis patients from 2019 to 2020 and measured their blood levels of iron, ferritin, TSAT, and total iron-binding capacity. We then compared these levels to how many patients had passed away within a year. Instead of just looking at low or high levels of these measures, we analyzed the full range of values to get a more detailed picture of any links between iron measures and mortality. Our findings showed that patients with low ferritin and TSAT levels had a higher risk of death. Interestingly, even in patients with high TSAT levels, there was a trend of increased death risk if ferritin was high. Conversely, when ferritin was low, patients tended to have a lower risk of death. These results highlight the importance of looking at iron levels in more detail rather than relying on a single cutoff point. This could help doctors make better decisions about iron treatments for people on dialysis, potentially reducing their risk of serious health issues.
