OBJECTIVES: Different erythropoiesis-stimulating agents (ESAs) are used to correct anaemia in haemodialysed patients. There is conflicting evidence on whether the dose needed to obtain the same haemoglobin level differs between ESAs. This study assessed the changes in ESA dose and the differences in cost of treatment when patients were switched from epoetin beta (EB) to darbepoetin alfa (DA). METHODS: A mono-centre retrospective chart review was performed. All haemodialysis patients switched from EB to DA during the first week of January 2008. The dose conversion from EB to used was 200IU:1µg based on the European DA label. In patients dialysed for at least 9 months at conversion, ESA dose and haemoglobin level were collected 3 months prior (baseline) to 12 months after conversion. The ratio “average weekly ESA dose/average weekly haemoglobin level”, the average weekly ESA-drug-related cost per patient (Belgian public payer’s perspective), the average weekly dose of ESA and the average weekly haemoglobin were compared for the baseline period vs. weeks 14-26 and 40-52 post-switch using the Wilcoxon signed rank test. RESULTS: Out of 144 screened patients, 96 were eligible and survived without renal transplantation until week 52. The ratio “average weekly ESA dose/average weekly haemoglobin level” decreased from 611IU/g/dL to respectively 359IU/g/dL and 348IU/g/dL in the defined post-switch periods (p<0.0001), without any change in average haemoglobin. A substantial reduction in drug cost was observed after switch (from €66.8 to €53.6 and €52.8/week). The average weekly ESA dose decreased from baseline to post-switch from 7230IU to 4203IU and 4137IU (p<0.0001). Both ESA dosing and haemoglobin were stabilised after a 13-weeks titration period post-switch. CONCLUSIONS: Switching patients from EB to DA resulted in a significant decrease of the ESA dose needed to obtain the same haemoglobin level. This significant decrease in dosage resulted in a substantial decrease in drug costs.