Dosing intervals and hemoglobin control in patients with chronic kidney disease and anemia treated with epoetin alfa or darbepoetin alfa: a retrospective cohort study.

BACKGROUND: Anemia is a common complication of chronic kidney disease (CKD). The approved dosing interval for currently available erythropoiesis-stimulating agents (ESAs) is 2 to 3 times weekly for epoetin alfa (EPO) and every 1 to 2 weeks for darbepoetin alfa (DARB). However, clinicians sometimes use less frequent dosing in the interest of convenience.

OBJECTIVES: This study investigated patterns of actual ESA use (doses and dosing intervals) and hemoglo- bin (Hb) control in adult outpatients with CKD not requiring dialysis at the Cleveland Clinic Foundation anemia clinic. The distribution of and variability in Hb levels in these patients were also examined.

METHODS: The clinical charts and electronic records of adult outpatients with CKD who initiated ESA therapy before March 2005 were reviewed to identify the initial, dominant (used for the longest consecutive period), and final dosing intervals and mean weekly doses of EPO and DARB. Hb control was examined in terms of maximum deviations >12 g/dL and <11 g/dL, and the proportions of measurements outside these values.

RESULTS: The analysis included data from 111 outpatients (mean [SD] age, 65.9 [14.4] years; 53.2% male; 66.7% white, 29.7% black, 2.7% other, 0.9% unknown ethnicity). Twenty-one patients received EPO only, 74 received DARB only, and 16 switched ESAs. The mean duration of follow-up was 20.5 months. The most common initial dosing intervals were qwk for EPO (66.7%) and q2wk for DARB (90.5%). The dominant dosing intervals were q2wk in 61.9% of EPO patients and q3wk in 62.3% of DARB patients. However, 80.0% of those who received EPO q2wk and 63.2% of those who received DARB q3wk eventually returned to their initial dosing intervals. The largest proportions of Hb mea- surements <11 g/dL occurred at dominant dosing intervals of qwk for EPO and q2wk for DARB (both, 46.0%; 11 and 26 patients, respectively), whereas the largest proportions of measurements >12 g/dL occurred with EPO dosed at q2wk (44.0%; 5 patients) and DARB dosed at >q4wk (62.0%; 5 patients).

CONCLUSIONS: The patterns of ESA usage in adult outpatients with CKD at this center indicated that clinicians extended dosing intervals beyond those in the approved prescribing information. However, variations in Hb concentrations occurred during maintenance therapy administered at extended dosing intervals, resulting in the resumption of shorter dosing intervals in the majority of patients.