Higher Conversion Ratio for Epoetin Beta to Darbepoetin Alfa
Researchers confirmed higher dose conversion ratios in Taiwanese patients with stable hemoglobin.
For Asian hemodialysis (HD) patients with stable hemoglobin (Hb) levels, the dose conversion ratio when switching from epoetin beta to darbepoetin alfa is greater than 200 IU: 1 µg, a Taiwanese study confirms.
Researchers led by Jin-Bor Chen, MD, of Kaohsiung Chang Gung Memorial Hospital in Taiwan, sought to validate the higher conversion ratios found by previous studies using an Asian population. They assessed Taiwanese HD patients from 5 hospital centers for Hb stability (Hb fluctuation less than 1g/dL) and no iron deficiency. Then, they randomly assigned 135 Hb stable patients to intravenous epoetin beta or darbepoetin alfa for 24 weeks. To start, the conversion ratio per dose for the darbepoetin alfa group was a default 200 IU: 1 µg. During 20 weeks, patients underwent dose adjustment and observation. In the final 4 weeks, dosages were maintained and Hb levels were evaluated at the constant dose. The target was set to an Hb level of 11.0 g/dL, in agreement with Taiwan guidelines.
Hb levels remained stable during the 24-week study period, according to results published online ahead of print in Therapeutic Apheresis and Dialysis. Patients were stratified according to Hb levels of 8.0–10.0 g/dL (low) and 10–11.0 g/dL (high) for analysis. At week 24, the dose conversion ratio was higher for the high Hb group than the low Hb group (296.4 IU epoetin beta: 1 µg darbepoetin alfa vs. 277.2 IU epoetin beta: 1 µg darbepoetin alfa). The achievement of the target Hb level of 11.0 g/dL was met by 17.39% of the darbepoetin alfa group.
Darbepoetin alfa did not show any increased Hb concentrations when compared with epoetin beta in the low Hb stratum, but it was more beneficial in the high Hb stratum, the investigators observed. They further noticed that Hb concentrations were more stable within a narrow range when switching to darbepoetin alfa in the low Hb stratum.
Other results indicated that darbepoetin alfa is advantageous for maintaining Hb stability on lower epoetin beta doses (mean 5860 IU/week, range 2000–15,000 IU/week) prior to switching, Dr Chen and colleagues stated.
The findings agreed with previous studies finding increased conversion ratios in patients with relative erythropoietin resistance. The actual conversion ratios were lower than previously reported. A Japanese study by Takayuki Hirai, et al., for example, found a conversion ratio of 350.5 IU: 1 µg (Nephron Clin Pract 2009;111:c81-c86).
Among the limitations, the study authors noted that the dose conversion ratio used was at the discretion of the treating nephrologists and might have differed from protocol.
- Liao SC, Hung CC, Lee CT, et al. Switch From Epoetin Beta to Darbepoetin Alfa Treatment of Anemia in Taiwanese Hemodialysis Patients: Dose Equivalence by Hemoglobin Stratification. Therapeutic Apheresis and Dialysis. doi: 10.1111/1744-9987.12401.