Colon to Rectum
Gut. 2023;72(4):644−53
Hypophosphatemia following ferric derisomaltose and ferric carboxymaltose in patients with iron deficiency anemia due to inflammatory bowel disease (PHOSPHARE-IBD): A randomized clinical trial
Objective: Intravenous iron – a common treatment for anemia and iron deficiency due to inflammatory bowel disease (IBD) – can cause hypo-phosphatemia. This trial compared the incidence of hypophosphatemia after treatment with ferric carboxymaltose (FCM) or ferric derisomaltose (FDI).
Design: This randomized, double-blind, clinical trial was conducted at 20 outpatient hospital clinics in Europe (Austria, Denmark, Germany, Swe-den, UK). Adults with IBD and iron deficiency anemia (IDA) were randomized 1:1 to receive FCM or FDI at baseline and at day 35 using identical hemoglobin- and weight-based dosing regimens. The primary outcome was the incidence of hypophosphatemia (serum phosphate < 2.0 mg/dl) at any time from baseline to day 35 in the safety analysis set (all patients who received ≥ 1 dose of study drug). Markers of mineral and bone homeostasis, and patient-reported fatigue scores, were measured.
Results: A total of 156 patients were screened; 97 (49 FDI, 48 FCM) were included and treated. Incident hypophosphatemia occurred in 8.3% (4/48) FDI-treated patients and in 51.0% (25/49) FCM-treated patients (adjusted risk difference, -42.8% [95% confidence interval: -57.1 to -24.6%]; p < 0.0001). Both iron formulations corrected IDA. Patient-reported fatigue scores improved in both groups, but more slowly and to a lesser extent with FCM than FDI; slower improvement in fatigue was associated with greater decrease in phosphate concentration.
Conclusion: Despite comparably effective treatment of iron deficiency anemia, ferric carboxymaltose (FCM) caused a significantly higher rate of hypophosphatemia than ferric derisomaltose (FDI). Further studies are needed to address the longer-term clinical consequences of hypophos-phatemia and to investigate mechanisms underpinning the differential effects of FCM and FDI on patient-reported fatigue.