Study to Assess Darbepoetin Alfa Dosing for the Correction of Anemia in Pediatric Patients With Chronic Kidney Disease

The time from study Day 1 to the day a participant first achieved hemoglobin ≥ 10.0 g/dL for participants who achieved hemoglobin ≥ 10.0 g/dL.

The darbepoetin alfa dose at the time a participant achieved a first hemoglobin level ≥ 10.0 g/dL, divided by the participant's weight measured at the closest study week prior to the dosing, post dialysis.

Arithmetic means are provided; Withheld doses are counted as 0 μg.

The PedsQL is a health-related quality of life (HRQOL) questionnaire that can be used to measure quality of life in children ≥ 2 years old. The 23-item PedsQL 4.0 includes physical functioning (8 items), emotional functioning (5 items), social functioning (5 items), and school functioning (5 items). Separate questionnaires for ages 2 to 4 (toddler), 5-7, 8-12, and 13-18 years are used for parent proxy-reporting, which assesses parents' perceptions of their child's HRQOL. The instructions ask how much of a problem each item has been during the past 1 month; each item is answered on a 5-point scale: 0 = never a problem; 1 = almost never a problem; 2 = sometimes a problem; 3 = often a problem; 4 = almost always a problem. Scores from the 4 subscales, the total score, and the psychosocial composite score were generated using standard algorithms. Each item's score in the questionnaire was converted to a 0 to 100 scale (with higher scores indicating better HRQOL).

The PedsQL child self-reported questionnaire was used in children > 5 years old. The 23-item PedsQL 4.0 includes physical functioning (8 items), emotional functioning (5 items), social functioning (5 items), and school functioning (5 items). Separate questionnaires for ages 5-7, 8-12, and 13-18 years was used for child self-reporting. The instructions asked how much of a problem each item has been during the past 1 month; each item is answered on a 5-point scale for ages 8 to 18 (0 = never a problem; 1 = almost never a problem; 2 = sometimes a problem; 3 = often a problem; 4 = almost always a problem), or simplified to a 3-point scale for ages 5 to 7 (0 = not at all a problem; 2 = sometimes a problem; 4 = a lot of a problem). Scores from the 4 subscales, the total score, and the psychosocial composite score were generated using standard algorithms. Each item's score in the questionnaire was converted to a 0 to 100 scale (with higher scores indicating better HRQOL).

A serious adverse event (SAE) is defined as an adverse event that meets at least one of the following serious criteria: • is fatal, • is life threatening, • requires in-patient hospitalization or prolongation of existing hospitalization, • results in persistent or significant disability/incapacity, • is a congenital anomaly/birth defect, and/or • other significant medical hazard. The investigator assessed whether the adverse event was related to the investigational product (IP). Events of interest included hypertension, ischemic heart disease, cardiac failure, cerebrovascular disorders, convulsions, embolic and thrombotic events, embolic and thrombotic events: venous, embolic and thrombotic events: arterial, embolic and thrombotic events: vessel type unspecified and mixed arterial and venous, dialysis vascular access thrombosis, antibody-mediated pure red cell aplasia, hypersensitivity, lack of efficacy-effect, and malignancies.

Calculated using the serial method as the change in hemoglobin from the previous non-missing hemoglobin level divided by number of days in between, and then multiplied by 7.

The maximum increase between any 2 non-missing hemoglobin measurements over any 2-week period from Day 1.

Participants who were negative for anti-erythropoiesis antibodies at Baseline (pre-dose) and who developed anti-erythropoiesis antibodies during the study. Serum samples were tested using Amgen's Surface Plasmon Resonance Immunoassay (SPRIA) method.

Serum concentrations of darbepoetin alfa were measured by an enzyme-linked immunosorbent assay (ELISA).