Hemoglobin and Clinical Outcomes in Hemodialysis: An Analysis of US Medicare Data From 2018 to 2020.

Rationale & Objective: Anemia management in patients treated with maintenance dialysis remains a challenge. We sought to update information in this area by evaluating the association between hemoglobin and various outcome and utilization measures using data-rich Medicare sources. Study Design: Observational cohort study using data from the Consolidated Renal Operations in a Web-enabled Network and Medicare claims. Setting & Participants: We studied 371,250 prevalent patients treated with hemodialysis, covering 3,326,072 patient-months in 2019. Exposure: Monthly patient hemoglobin concentrations. Outcomes: We examined several outcomes, including mortality, all-cause hospitalization, cause-specific hospitalization, and emergency department utilization in the month following the exposure measurement. Analytical Approach: For each monthly observation period, we calculated unadjusted and adjusted (for demographics and comorbid condition) hazard ratios using Cox regression. Results: The hemoglobin concentration was <10.5 g/dL for 40% of observations. We found an inverse association between mortality and hemoglobin measured over a range from <9 g/dL (HR, 2.53; 95% CI, 2.45-2.61; Limitations: As with prior observational studies, the observed associations are not necessarily causal. Conclusions: In a large US hemodialysis population, there were better clinical outcomes at higher hemoglobin concentrations over short exposure and follow-up periods, consistent with other observational studies that generally used longer exposure and follow-up times. Mortality risk increased at hemoglobin concentrations >11.5 g/dL, consistent with findings from erythropoiesis-stimulating agent clinical trials. The apparently beneficial short-term effects associated with higher hemoglobin concentrations suggest that hemoglobin measurements capture unmeasured elements of patient risk.