Once weekly darbepoetin alfa is more cost effective than thrice weekly IV epoetin alfa when given intravenously - a prospective, cohort study.

L Ridley, D Richardson, C Barlett, C Jones, D Worth, P Laboi

York Hospital

Problem: Following the recognition of primary red cell aplasia associated neutralizing antibody to subcutaneous epoetin alfa (Eprex)(EPO) we converted our haemodialysis population to IV EPO. This conversion resulted in a significant increase in EPO dose required to maintain haemoglobin outcome. The European recommended dose conversion ratio (described as the total weekly dose of EPO divided by 200) was used to convert IV EPO to IV darbepoetin alfa (DA). The conversion ratio may vary according to route and frequency of administration and result in a change in haemoglobin (Hb) outcome.

Purpose: The study aimed to identify any difference in the dose of erythropoietic protein therapy (EPT) required to maintain Hb outcome compliant with UK Renal Association standards of 85%>10g/dl when converting from three times a week intravenous EPO to once weekly intravenous DA.

Design: We have previously described the use of a computerised decision support system for the management of renal anaemia in our haemodialysis population. The use of this system allows the Hb outcome to be ‘locked’ by defining an intervention threshold and ceiling. A sustained and predictable outcome is achieved. Using this system we prospectively converted our haemodialysis population from IV EPO to IV DA at an initial ratio of 200:1 and studied the equivalent DA doses required to maintain outcome. The intravenous iron sucrose (IVFE) protocol remained unchanged throughout.

Findings: The population (n =109) was studied for 6 months including 4 months following conversion. 84 patients have completed 6 months study. Reasons for exclusion were lack of need for EPT (7), intolerance of IV iron (2), death (11), transfer of unit (1), transplantation (4). The mean (+/-S.D.) Hb at time -2, 0 and +4 months were 11.7(1.3), 12.0(1.4) and 12.7(1.9) g/dl (p<0.001). The median and inter-quartile range (IQR) for ferritin outcomes at month -2, 0 and +4 were 575 (454-673), 543 (449-731) and 660 (513-828). Mean weekly EPO dose/200 and DA doses at time 0 and +4 were 55.8, 55.7 and 49.6 mcg/wk (p=0.006). Mean IVFE doses were 64, 58 and 39mg/wk (p=0.03). There was no significant change in CRP levels during the study. DA and IVFE doses were still falling at 4 months and the Hb has yet to be brought back to baseline.

Conclusion: In this controlled system, conversion from three times a week IV EPO to once a week IV DA resulted in a significant reduction in equivalent dose of EPT and IVFE. The mean Hb increased with a corresponding reduction in the mean weekly dose of DA. Further dose reductions may be possible in the coming months.

Relevance: When administered intravenously once weekly darbopoetin is more cost effective than thrice weekly IV epoetin alfa at a 200:1 conversion ratio when used within our anaemia management algorithm. Return of Hb to baseline is required in order that the new conversion ratio can be calculated.