Longitudinal associations between iron status and patient-reported outcomes in incident dialysis patients: a DOMESTICO substudy

Background: More liberal use of iron therapy is favored in dialysis patients based on lower erythropoietin need and clinical outcomes. However, it remains unclear whether higher iron stores are associated with better patient-reported outcomes. We assessed the longitudinal associations of ferritin and transferrin saturation (TSAT) levels with patient-reported outcomes in incident dialysis patients. Methods: This prospective cohort study included incident dialysis patients who had completed at least one patient-reported outcome questionnaire and had undergone a laboratory assessment (e.g., ferritin, transferrin saturation, hemoglobin) within the first year of dialysis. The primary outcome was health-related quality of life (HRQoL), measured using the 12-Item Short Form (SF-12) survey. Secondary outcomes were the presence of anemia-related symptoms, measured using the Dialysis Symptom Index. We used sequential conditional mean models to adjust for baseline and time-varying confounding. Results: We included 1069 incident dialysis patients, of whom 76% initiated hemodialysis. The mean (SD) age was 64.0 (14.2) years and 34% were female. Over a 1-year follow-up, patients with ferritin levels < 200, > 500 − 700, and > 700 ng/mL did not have a significantly different HRQoL compared to those with levels between 200 − 500 ng/mL, chosen as reference. Similarly, patients with TSAT levels < 20 or ≥ 40% did not have a significantly different HRQoL compared to those with levels between 20 − 39%. No significant differences were found in the odds of experiencing fatigue, shortness of breath, muscle cramps or restless legs between the ferritin and TSAT groups. Conclusion: Differences in iron status parameters were not associated with differences in patient-reported outcomes during the first year of dialysis. Our findings therefore suggest that decisions on iron therapy should be guided by target hemoglobin levels and clinical outcomes in dialysis patients.