Efficiency of ferric carboxymaltose in non-dialysis CKD patients and its impact on kidney function: a prospective observational study

Background: Iron deficiency anemia occurs in most patients with non-dialysis chronic kidney disease (ND-CKD). Previous studies have suggested that intravenous (IV) iron therapy is more effective than oral iron in these patients. Clinical evidence relating the effects of IV iron on renal function is, however, limited.

Methods: Prospective observational study of adult patients with ND-CKD, anemia, iron deficiency, and estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², treated with a single dose of 500 mg or 1000 mg of ferric carboxymaltose (FCM) and followed-up for 24 weeks. Primary outcome was FCM efficacy, assessed by comparing Hb, TSAT and ferritin at 24 weeks with those at baseline. Secondary outcome was FCM impact on renal function, evaluated by comparing eGFR over the same period.

Results: One hundred and forty patients were recruited: seventy-eight (55.7%) were treated with 1000 mg and 62 (44.3%) with 500 mg of FCM. 24 weeks after FCM administration, Hb increased 1.54 ± 1.99 g/dL (95% CI 1.09-1.99, p = 001) in the group treated with 1000 mg and 0.86 ± 1.4 g/dL (95% CI 0.53-1.22, p = 0.001) in those treated with 500 mg. TSAT increased in both groups but more in those treated with 1000 mg, and ferritin only increased in the latter. Estimated GFR showed a significant increase of 1.55 ± 6.86 mL/min/m² (95% CI 0.05-3.09, p = 0.049), from a baseline of 27.73 ± 17.23 to 28.88 ± 18.02 mL/min/m² in the group treated with 1000 mg.

Conclusions: Our findings suggested that IV FCM therapy was effective in improving serum iron levels and anemia in ND-CKD stage 3 to 5 patients. Higher doses seem to be necessary to replace depleted iron stores. In our cohort, IV FCM therapy was associated with an improvement in renal function, particularly in those treated with higher doses of FCM.