Nutritional Status Modifies the Association Between Hemoglobin Level and Mortality in Older Patients Undergoing Hemodialysis: A Nationwide Dialysis Registry in Japan.

Objectives: Anemia is a common complication associated with adverse outcomes in older patients undergoing hemodialysis (HD). They also tend to experience malnutrition, which can affect the course of anemia. We hypothesized that the optimal hemoglobin (Hb) level varies depending on nutritional status in older patients undergoing HD and aimed to investigate the association between Hb levels and mortality according to nutritional status.

Methods: This is an observational study utilizing a nationwide Japanese database from 2019 to 2021. This study included 95,771 patients aged ≥75 years undergoing HD thrice a week. The nutritional risk index for Japanese hemodialysis patients (NRI-JH) was calculated. The association between Hb levels and mortality was investigated using Cox regression analysis stratified by NRI-JH. A nonlinear relationship was investigated using restricted cubic spline analysis.

Results: During a median follow-up period of 24 months, 27,611 patients died. In the low-risk NRI-JH group, the risk of all-cause mortality was higher in the Hb categories of <9.0, 9.0-9.9, and ≥13 g/dL compared to the reference Hb category of 10-10.9 g/dL, with the adjusted hazard ratios and 95% confidence intervals of 1.45 (1.32-1.59), 1.15 (1.08-1.22), and 1.18 (1.07-1.29), respectively. In contrast, the impact of Hb levels on mortality was significantly attenuated in the high-risk NRI-JH group, with a mild increased risk in the <9.0 g/dL category (adjusted hazard ratio, 1.07; 95% confidence interval, 1.01-1.15).

Conclusion: Among older patients undergoing HD, the impact of Hb levels on mortality was attenuated in the high-risk NRI-JH group.