Ferric citrate matched sevelamer on phosphate and raised the haemoglobin as well

Design

Phase 3, multicentre, randomised, open-label, active-controlled non-inferiority trial

Population

239 Chinese patients with hyperphosphataemia on maintenance haemodialysis; 119 ferric citrate, 120 sevelamer carbonate

Primary outcome

Change in serum phosphate from baseline to week 12, non-inferiority margin 0.32 mmol/L

Effect

-0.70 vs -0.61 mmol/L; least-squares mean difference -0.09 (95% CI -0.24 to 0.05); target achieved 49.1% vs 48.3% (p=0.902)

Patients on maintenance haemodialysis routinely take a phosphate binder and an iron preparation, and the two are usually separate problems with separate tablets. This phase 3 multicentre, open-label, non-inferiority trial randomised 239 Chinese patients with hyperphosphataemia to ferric citrate (n=119) or sevelamer carbonate (n=120) for 12 weeks.

On the primary endpoint, serum phosphate fell by 0.70 mmol/L with ferric citrate and 0.61 with sevelamer - a least-squares mean difference of -0.09 mmol/L (95% CI -0.24 to 0.05) against a non-inferiority margin of 0.32, so non-inferiority was met with room to spare. Target phosphate was reached by 49.1% and 48.3% respectively (p=0.902). Ferric citrate significantly improved iron-related parameters and haemoglobin. Most treatment-emergent adverse events were mild, with gastrointestinal disorders commonest in both groups.

The iron effect is the reason to care. A binder that also delivers absorbable iron reduces the number of tablets and may reduce erythropoiesis-stimulating agent and intravenous iron requirements - not measured here, and worth knowing was not measured. Twelve weeks is also short for a drug taken indefinitely, and an open-label design in a single country limits how far the tolerability findings travel.

For Indian dialysis units the calculation is mostly about cost and pill burden, both of which favour whichever binder is cheapest locally. What this trial adds is that choosing ferric citrate does not mean accepting worse phosphate control, and that a patient with both hyperphosphataemia and iron deficiency has a binder that addresses both. Watch for iron overload in patients already receiving intravenous iron, which this trial does not settle.

• Consider ferric citrate where a dialysis patient has both hyperphosphataemia and iron deficiency
• Recheck ferritin and transferrin saturation after switching - absorbed iron is the point and the risk
• Review intravenous iron and erythropoiesis-stimulating agent doses after the switch
• Warn about gastrointestinal upset and black stools; both are common and both cause non-adherence
• Twelve weeks of data on a lifelong drug - reassess phosphate control at three and six months

The statistics, in plain English

Non-inferiority means the trial set out to show ferric citrate is not meaningfully worse, not that it is better - and the pre-specified margin, 0.32 mmol/L, is the amount of extra phosphate the investigators decided was acceptable to lose. The confidence interval, -0.24 to 0.05, sits entirely inside that margin, so the conclusion holds. Note it crosses zero, so the two drugs are statistically indistinguishable rather than one being superior. An open-label design matters less for a laboratory endpoint like phosphate than it does for the tolerability comparison.

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