Iron Deficiency at ICU Discharge

Iron Deficiency at ICU Discharge and Its Impact on Post-critical Illness Recovery. The IRON-ICU Study

IRON-RECOVERY is a prospective, multicenter, observational cohort study designed to determine the prevalence of iron deficiency at intensive care unit (ICU) discharge and to evaluate its association with post-ICU clinical recovery.

Anemia is highly prevalent in critically ill patients and frequently persists after ICU discharge. Although inflammation-induced iron dysregulation is considered one of the main mechanisms underlying persistent anemia, iron deficiency remains largely under-recognized in this population because conventional biomarkers, particularly ferritin, are influenced by the inflammatory response. Transferrin saturation (TSAT) has emerged as a more reliable marker of iron availability and may better identify patients with iron-restricted erythropoiesis.

Adult patients admitted to participating ICUs for at least 72 hours will undergo assessment of iron status at ICU discharge using routine laboratory tests, including hemoglobin, serum iron, transferrin, ferritin, TSAT, and inflammatory markers. When available, admission iron parameters will also be collected to evaluate changes during the ICU stay. No study-specific therapeutic intervention will be mandated, and all treatment decisions, including intravenous iron administration, will remain at the discretion of the treating physicians.

The primary objective is to determine the prevalence of iron deficiency (defined as TSAT <20%) at ICU discharge. Secondary objectives include evaluating the association between iron deficiency and post-ICU red blood cell transfusion requirements, hemoglobin recovery, functional status assessed by EQ-5D, hospital readmission, mortality, and days alive and out of hospital. Exploratory analyses will assess the association between intravenous iron therapy and clinical outcomes after adjustment for confounding factors. Also, risk factors for ICU-acquired iron deficiency will be investigated.

The findings of this study are expected to provide the first prospective multicenter estimate of iron deficiency at ICU discharge and to inform the design of future interventional trials evaluating iron replacement as part of post-ICU patient blood management strategies.

Inclusion criteria:

• Age ≥18 years
• ICU length of stay ≥72 hours
• Survival to ICU discharge

Exclusion criteria:

• Known hematologic diseases affecting erythropoiesis (e.g., aplastic anemia, myelodysplastic syndromes)
• Pregnancy