Dosing patterns and treatment costs of erythropoietic agents in elderly patients with pre-dialysis chronic kidney disease in managed care organisations.

OBJECTIVES: To investigate dosing patterns and drug costs of erythropoietic agents and assess the frequency of outpatient nephrologist visits in an elderly population with pre-dialysis chronic kidney disease (pCKD) newly initiated on epoetin alfa (EPO) or darbepoetin alfa (DARB).
METHODS: An analysis of medical claims from more than 30 healthcare plans covering all census regions of the US in the period July 2002 through February 2005 was conducted. Patients were included if they were > or = 65 years of age, had at least one claim for CKD within 90 days prior to the initiation of any erythropoietic agent, were newly commenced on either EPO or DARB, and had received at least two treatment doses. If a patient received renal dialysis, data were censored 30 days prior to the first date of dialysis. Patients diagnosed with cancer or those who had undergone chemotherapy were excluded from the analysis. The average dosing interval for both EPO and DARB was calculated and classified as once weekly (qw), every 2 weeks (q2w) or every 3 weeks or less frequently (> or = q3w). Weighted average weekly doses were scaled based on treatment duration. The frequency of outpatient nephrologist visits was analysed. Average weekly treatment costs were calculated and presented using the May 2005 Wholesale Acquisition Costs.
RESULTS: A total of 293 EPO and 102 DARB patients met the inclusion criteria. The two groups of patients had similar mean age (74.4 years for EPO vs 74.3 years for DARB) and gender distribution (47.4% female for EPO vs 51.0% for DARB). Extended dosing (every 2 weeks or less frequently: > or = q2w) during treatment was observed in both groups (EPO: qw 49.8%, q2w 31.7%, > or = q3w 18.4%; DARB: qw 19.6%, q2w 52.9%, > or = q3w 27.5%). The average dosing interval between injections was 13.6 days for the EPO group and 17.3 days for the DARB group. The weighted average weekly dose was 12,748 units for EPO and 43.5 microg for DARB. The average weekly erythropoietic treatment cost was significantly greater for DARB compared with EPO (190 US dollars vs 155 US dollars per week [2005 values]; p = 0.028). After controlling for covariates, the cost difference between the two groups was more pronounced and remained statistically significant (adjusted cost difference 41 US dollars/week higher for DARB patients; p = 0.013). The frequency of outpatient nephrologist visits during treatment was similar between the two groups (EPO 3.4 vs DARB 3.0 visits).
CONCLUSIONS: Based on this analysis of claims data from more than 30 US healthcare plans, extended dosing (> or = q2w) of EPO and DARB was common in elderly pCKD patients treated with erythropoietic agents, with significantly higher weekly drug costs observed in the DARB group compared with the EPO group. The number of outpatient nephrologist visits was not significantly different between EPO and DARB patients. This study was the first to evaluate the dosing patterns of EPO and DARB in elderly pCKD patients in a large managed care population.