Preoperative iron deficiency increases transfusion requirements and fatigue in cardiac surgery patients: a prospective observational study.

Background: Iron deficiency is the commonest cause of anaemia. It is apparent preoperatively in cardiac surgery patients and may influence transfusion requirements. In addition, iron deficiency per se is associated with fatigue.
Objective: To determine the prevalence of preoperative iron deficiency and its association with perioperative anaemia, blood transfusions and fatigue in cardiac surgery patients.
Setting: Academic hospital in Paris, France.
Patients: One hundred consecutive patients without known iron disorder and scheduled for cardiac surgery were prospectively included in this observational study.
Intervention: No intervention was performed.
Measurements: A biological iron profile (transferrin saturation, ferritin, soluble transferrin receptor and C-reactive protein) was assessed on the day of surgery. Diagnosis of iron deficiency was defined using a previously published algorithm. Patient fatigue was assessed before surgery and 1 week afterwards (day 7) using the Multidimensional Fatigue Inventory (MFI-20) score that quotes five distinctive dimensions of fatigue.
Results: Thirty-seven out of 100 patients were diagnosed with iron deficiency. These patients were younger [median (first-third quartile) 63 (43-70) vs. 70 (59-77) years (P = 0.004)], and more often female (51 vs. 21%, P = 0.003), than no iron deficiency patients. Preoperative iron deficiency was associated with lower preoperative haemoglobin levels (P = 0.006) and higher perioperative transfusion rates during the first week (62 vs. 35%, P = 0.019). Patients with iron deficiency but without anaemia (n = 25) received more packed red blood cells units than those without iron deficiency or anaemia (n = 50) [2 (0-2) vs. 0 (0-0) units, P < 0.05). Preoperative iron deficiency was associated with higher score of physical fatigue on day 7 (P = 0.01).
Conclusion: Preoperative iron deficiency is frequent among cardiac surgery patients and is associated with anaemia, higher transfusion requirements and postoperative fatigue.