Participants received peginesatide by intravenous injection once every 4 weeks. The starting dose was based on the participant's total weekly epoetin alfa dose during the last week of the Screening Period; the first dose was administered one week after the last epoetin alfa dose. The dose was adjusted to maintain hemoglobin levels in a target range of 10.0-12.0 grams per deciliter (g/dL) and ± 1.5 g/dL from baseline during the Titration and Evaluation Periods, and 10.0-12.0 g/dL during the Long-Term Safety and Efficacy Period.

Participants continued to receive commercially available epoetin alfa by intravenous injection, at the same starting dose and frequency as received during the last week of the Screening Period, with the first study dose of epoetin alfa administered after randomization at Week 0. The dose was adjusted to maintain hemoglobin levels in a target range of 10.0-12.0 g/dL and ± 1.5 g/dL from baseline during the Titration and Evaluation Periods, and 10.0-12.0 g/dL during the Long-Term Safety and Efficacy Period.

The sample size for this study was determined based on a two group evaluation of non-inferiority using the t-distribution (one-sided significance level 0.025) with a non inferiority margin of -1.0 g/dL. A sample size of approximately 750 (peginesatide group of 500 and epoetin alfa group of 250) provided at least 99% power for the evaluation of non-inferiority, assuming an expected treatment difference of 0.0 g/dL and a standard deviation of 1.5 g/dL.

The ANOVA cell means model was used to estimate primary efficacy endpoint within the specified cells formed by the combination of treatment and strata

Participants received peginesatide by intravenous injection once every 4 weeks. The starting dose was based on the participant's total weekly epoetin alfa dose during the last week of the Screening Period; the first dose was administered one week after the last epoetin alfa dose. The dose was adjusted to maintain hemoglobin levels in a target range of 10.0-12.0 grams per deciliter (g/dL) and ± 1.5 g/dL from baseline during the Titration and Evaluation Periods, and 10.0-12.0 g/dL during the Long-Term Safety and Efficacy Period.

Participants continued to receive commercially available epoetin alfa by intravenous injection, at the same starting dose and frequency as received during the last week of the Screening Period, with the first study dose of epoetin alfa administered after randomization at Week 0. The dose was adjusted to maintain hemoglobin levels in a target range of 10.0-12.0 g/dL and ± 1.5 g/dL from baseline during the Titration and Evaluation Periods, and 10.0-12.0 g/dL during the Long-Term Safety and Efficacy Period.

Participants received peginesatide by intravenous injection once every 4 weeks. The starting dose was based on the participant's total weekly epoetin alfa dose during the last week of the Screening Period; the first dose was administered one week after the last epoetin alfa dose. The dose was adjusted to maintain hemoglobin levels in a target range of 10.0-12.0 grams per deciliter (g/dL) and ± 1.5 g/dL from baseline during the Titration and Evaluation Periods, and 10.0-12.0 g/dL during the Long-Term Safety and Efficacy Period.

Participants continued to receive commercially available epoetin alfa by intravenous injection, at the same starting dose and frequency as received during the last week of the Screening Period, with the first study dose of epoetin alfa administered after randomization at Week 0. The dose was adjusted to maintain hemoglobin levels in a target range of 10.0-12.0 g/dL and ± 1.5 g/dL from baseline during the Titration and Evaluation Periods, and 10.0-12.0 g/dL during the Long-Term Safety and Efficacy Period.