Iron deficiency, anemia, and mortality in renal transplant recipients

Anemia, iron deficiency anemia (IDA), and iron deficiency (ID) are highly prevalent in renal transplant recipients (RTR). Anemia is associated with poor outcome, but the role of ID is unknown. Therefore, we aimed to investigate the association of ID, irrespective of anemia, with all-cause mortality in RTR. Cox regression analyses were used to investigate prospective associations. In 700 RTR, prevalences of anemia, IDA, and ID were 34%, 13%, and 30%, respectively. During follow-up for 3.1 (2.7-3.9) years, 81 (12%) RTR died. In univariable analysis, anemia [HR, 1.72 (95%CI: 1.11-2.66), P = 0.02], IDA [2.44 (1.48-4.01), P < 0.001], and ID [2.04 (1.31-3.16), P = 0.001] were all associated with all-cause mortality. In multivariable analysis, the association of anemia with mortality became weaker after adjustment for ID [1.52 (0.97-2.39), P = 0.07] and disappeared after adjustment for proteinuria and eGFR [1.09 (0.67-1.78), P = 0.73]. The association of IDA with mortality attenuated after adjustment for potential confounders. In contrast, the association of ID with mortality remained independent of potential confounders, including anemia [1.77 (1.13-2.78), P = 0.01]. In conclusion, ID is highly prevalent among RTR and is associated with an increased risk of mortality, independent of anemia. As ID is a modifiable factor, correction of ID could be a target to improve survival.