Temporal Dynamic of Hemoglobin Levels and Its Impact on Progression in Chronic Kidney Disease Stages 3- 4 Patients: A Retrospective Cohort Study

Background: Anemia is one of the most prevalent complications in patients with chronic kidney disease (CKD). Previous researches have indicated associations between anemia and renal outcomes. However, recurrent limitations in these studies are their exclusive reliance on baseline hemoglobin (Hb) levels, leaving the implications of longitudinal Hb fluctuations on the progression of CKD uncharted. Methods: In this cohort of 2,336 CKD stages 3-4 patients, we investigated the relationship between Hb levels, its temporal variations, and composite renal outcomes. Result: The average follow-up period was 552.5 days (289.3-971.0), with 834 individuals (35.7%) experiencing the composite renal endpoints. Using a fully adjusted cubic spline model with Hb treated as a continuous variable showed that the relationship between Hb and the renal composite outcomes was non-linear. Additionally, in an adjusted multivariate Cox model, participants in the Q4 (12-13 g/dL) and Q5 (>13 g/dL) groups with higher Hb levels had a significantly lower risk of composite renal outcomes compared to the Q1 group (<10 g/dL) (HR=0.57, 0.50, respectively, all p<0.001). A similar trend is observed in time-varying multivariate models that incorporate the longitudinal dynamics of Hb levels (HR=0.25, 0.25, respectively, all p<0.001). Conclusion: In the groups with higher Hb levels, the occurrence of renal endpoint events was notably lower than in the groups with lower Hb levels. Additionally, based on the longitudinal dynamics of Hb levels, the risk of renal endpoint events decreased progressively with rising Hb levels.