Association between hemoglobin levels and dialysis dependence in patients with acute kidney injury requiring continuous kidney replacement therapy: a multicenter retrospective cohort study

Background Anemia in patients with acute kidney injury (AKI) requiring continuous kidney replacement therapy (CKRT) significantly contributes to increased mortality and morbidity. However, its impact on dialysis dependence remains unclear. This study explored the association between anemia and dialysis dependence in patients with severe AKI undergoing CKRT. Methods In this retrospective cohort study, we included 2755 patients with AKI who underwent CKRT at four medical centers between 2006 and 2021. The primary exposure was the average hemoglobin (Hb) level during CKRT, with patients categorized into anemic (Hb < 8.44 g/dL) and control (Hb > 8.44 g/dL) groups. Dialysis dependence was defined at the time of hospital discharge. The odds ratio for dialysis dependence in the anemic group was calculated by adjusting for demographics and laboratory data. The impact of the duration of anemia was also assessed. Results Overall, 61.4% of patients were males, with a mean age of 65.5 years. The average duration of CKRT was 7.9 d, and 64.7% of the patients were dialysis-dependent at hospital discharge. A U-shaped relationship was found between Hb levels and dialysis dependence, with 8.44 g/dL as the critical threshold. Patients in the anemia group had a 57% increased risk of dialysis dependence, particularly among women, those under 65 years, patients with non-septic AKI, and those with lower Charlson comorbidity index scores. Each additional day of anemia increased the risk by 4%. Conclusion Hb levels < 8.44 g/dL during CKRT were associated with increased dialysis dependence. These findings highlight the significance of Hb thresholds for improving kidney recovery outcomes.