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NDT Advance Access originally published online on August 5, 2006
Nephrology Dialysis Transplantation 2006 21(10):2846-2850; doi:10.1093/ndt/gfl387
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© The Author [2006]. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

The efficacy of intravenous darbepoetin alfa administered once every 2 weeks in chronic kidney disease patients on haemodialysis

Fernando Carrera, Lino Oliveira, Pedro Maia, Teresa Mendes and Candido Ferreira

Dialysis Unit, Eurodial, Leiria, Portugal

Correspondence and offprint requests to: Dr Fernando Carrera, Eurodial, Rua da Carrasqueira, 19 Parceiros 2400-441 Leiria, Portugal. Email: fcarrera{at}mail.telepac.pt



   Abstract
Top
 Abstract
Introduction
 Subjects and methods
 Results
 Discussion
 Acknowledgements
 References
 
Background. It is becoming increasingly more common to administer intravenous (i.v.) darbepoetin alfa to haemodialysis (HD) patients at less frequent dosing intervals in routine clinical practice. This study investigated extending the dosing interval for i.v. darbepoetin alfa treatment from once a week (QW) to once every 2 weeks (Q2W) at the same dose in order to maintain target haemoglobin (Hb) concentrations (11–13 g/dl).

Methods. Stable HD patients in routine clinical practice receiving i.v. darbepoetin alfa QW for a period of 6 months (n = 105) (treatment period 1) were switched to i.v. Q2W darbepoetin alfa for a further 6 months (treatment period 2) (n = 90). The dose of i.v. darbepoetin alfa was titrated to maintain Hb concentrations between 11 and 13 g/dl throughout the full 12-month study period.

Results. The mean change in Hb for treatment period 2 was 0.04 ± 1.1 g/dl (±SD), which was not clinically relevant (11.7 ± 0.8 g/dl vs 11.7 ± 1.0 g/dl; P = 0.8). The mean weekly doses of darbepoetin alfa were similar throughout the treatment periods (34.0 ± 17.1 µg/week vs 32.1 ± 17.3 µg/week; P = 0.3, respectively for QW and Q2W dosing). Intravenous darbepoetin alfa was well tolerated.

Conclusions. The treatment of renal anaemia in HD patients with i.v. Q2W darbepoetin alfa effectively and safely maintains Hb concentrations at a less frequent dosing regimen than observed with QW administration. Dose requirements for i.v. darbepoetin alfa administered QW or Q2W were not different. The results of this study demonstrate that i.v. darbepoetin alfa administered Q2W is an effective regimen for HD patients requiring anaemia treatment in routine clinical practice.

Keywords: darbepoetin alfa; frequency of administration; haemodialysis (HD); intravenous dosing; once every 2 weeks dosing (Q2W); renal anaemia



   Introduction
Top
 Abstract
 Introduction
Subjects and methods
 Results
 Discussion
 Acknowledgements
 References
 
The treatment of renal anaemia using erythropoiesis stimulating agents (ESAs) [darbepoetin alfa and recombinant human erythropoietin (rHuEPO) alfa or beta] is now a common clinical practice in patients with chronic kidney disease (CKD), regardless of their dialysis status, such that there is an increasing need for consensus and guidelines on their use [1]. Despite their established role in the management of CKD patients, it remains important to further investigate how to utilize these agents in order to fully gain both the clinical and the economical benefits they can afford to in this ever-expanding patient population.

After nearly two decades of experience with these drugs, it has become increasingly common to administer ESAs at not only a reduced dosage, but also on a less frequent administration routine [1]. Clearly, this benefits both the patient and their healthcare providers, however, there is little reported experience from outside the clinical trial setting as to how such treatment regimens would routinely impact renal anaemia clinical practice in general.

In haemodialysis (HD) patients, darbepoetin alfa is usually administered once a week (QW) [1,2]. There are data from clinical trials to suggest that switching CKD patients receiving QW rHuEPO to once every 2 weeks (Q2W) darbepoetin alfa maintains target haemoglobin (Hb) concentration, without the need for an increase in dose [3–7]. However, there is little reported evidence, if any, of switching patients directly from QW darbepoetin alfa dosing to i.v. Q2W darbepoetin alfa, especially from a single dialysis centre during routine clinical practice.

The results of the present study offer an evaluation of stable HD patients being treated in routine clinical practice with i.v. darbepoetin alfa QW, who were subsequently converted to a Q2W treatment regimen in a dialysis centre over a 12-month treatment period.



   Subjects and methods
Top
 Abstract
 Introduction
 Subjects and methods
Results
 Discussion
 Acknowledgements
 References
 
This single centre, open label, prospective study in 105 patients (selected from a total of 111) with end-stage renal disease (ESRD) receiving HD evaluated the efficacy and safety of unit doses of darbepoetin alfa administered i.v. Q2W for the treatment of renal anaemia to patients previously receiving i.v. darbepoetin alfa QW. The study design is presented schematically in Figure 1. Clinically stable ESRD patients (≥18 years of age) with mean Hb concentrations between 11 and 13 g/dl receiving HD for at least 3 months were recruited from a single Portuguese dialysis centre (Eurodial, Leiria). The study protocol required that the patients were receiving a stable dose of i.v. darbepoetin alfa QW for 6 months (treatment period 1) prior to switching to the same dose of i.v. darbepoetin alfa Q2W for a further 6 months (treatment period 2). A stable dose is defined as ≤25% change in darbepoetin alfa dose over the 6-week period immediately prior to enrolment and with less than one missed dose over this period. To ensure adequate iron stores for supporting erythropoiesis, serum ferritin was required to be in the range 200–600 µg/l.


Figure 1
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  		Fig. 1. Study design.

 
The principal exclusion criteria for the study were: New York Heart Association class III or IV congestive heart failure, uncontrolled hypertension (diastolic blood pressure ≥110 mmHg prior to HD), concomitant infection, haematological disorders, inflammatory disease and epilepsy. Patients were also excluded if they had undergone major surgery or blood transfusions within 12 weeks before the 12-month study period, or were pregnant or lactating.

Prior to switching to i.v. darbepoetin alfa Q2W, patients received unit doses of i.v. darbepoetin alfa QW to maintain Hb concentrations between 11 and 13 g/dl for a period of 6 months. Human serum albumin-free darbepoetin alfa was available for administration at the following unit doses: 10, 15, 20, 30, 40, 50, 60, 80, 100 or 150 µg. After this initial 6-month treatment period, patients were switched from a QW frequency administration to Q2W, but at the same total weekly dose (i.e. no dose adjustment) for a further 6 months. Intravenous iron supplementation was administered to maintain serum ferritin in the range 200–600 µg/l.

Darbepoetin alfa dosing was adjusted to maintain each patient's Hb concentration within a target range of –1.0 to +1.5 g/dl of the mean baseline Hb and between 11 and 13 g/dl throughout the 12-month study period. Dose increases or decreases were made according to the NESP guidelines [2]. If a patient's Hb fell below the target range on two consecutive assessments, then the dose of darbepoetin alfa was increased to the next higher unit dose. Conversely, if a patient's Hb increased above the target range on two consecutive assessments then the dose of darbepoetin alfa was decreased to the next lower unit dose. Any change in dose was one step up or down in the list of provided unit doses. Blood samples for Hb, serum ferritin and transferrin saturation measurements were taken monthly throughout the study period. Laboratory parameters were also monitored. There were no changes in HD format (conventional HD), dialysis membranes or the dialysis machine throughout the study period.

The primary efficacy endpoints were the change in Hb between the switch from QW to Q2W administration, and the dose of darbepoetin alfa administered during the study. Safety variables assessed the nature, frequency, severity, relation to treatment and the outcome of all adverse events.

Statistical analysis
In this analysis, variables were expressed as mean values with SD for continuous parameters and frequencies with percentages for categorical parameters. Changes in Hb and darbepoetin alfa mean values were evaluated using a paired t-test. Categorical parameters association was evaluated using the {chi}2 test. Analyses were conducted in the per-protocol and intent-to-treat (ITT) patient populations.

For all comparisons a P-value <0.05 was considered statistically significant. Statistical analyses were performed using SPSS v13.0.



   Results
Top
 Abstract
 Introduction
 Subjects and methods
 Results
Discussion
 Acknowledgements
 References
 
In total, 107 patients from our unit were considered eligible for study inclusion (Figure 2). Of these patients, two were not included because they had concomitant severe haematological disease. Therefore, 105 patients were subsequently included in the 12-month study period. Patient demography and baseline characteristics are shown in Tables 1 and 2. In total, 80 patients completed the study. Discontinuations were due to death (17 patients) and also transfusions relating to either gastrointestinal bleeding (two patients) or major surgery (six patients). All deaths were considered to be unrelated to study treatment. Ten of the 17 deaths occurred during the QW period and seven occurred during the Q2W period. Of the eight patients who discontinued the study because of blood transfusions, five withdrew in the QW period and three in the Q2W period.


Figure 2
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  		Fig. 2. Patient disposition.

 

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  		Table 1. Patient demography

 

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  		Table 2. Patient baseline characteristics

 
The mean Hb concentration at the outset for patients included in the study population was 11.75 ± 1.66 g/dl (mean ± SD; n = 105). At the end of the first treatment period (treatment period 1) during which patients received darbepoetin alfa QW, Hb was 11.46 ± 1.6 g/dl (mean ± SD). After switching to Q2W dosing and completing the 12-month study period, the Hb concentration in these patients was 11.54 ± 1.6 g/dl (mean ± SD). For comparison, mean changes in Hb concentration from baseline to the end of each treatment period in the protocol population are shown in Table 3.


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  		Table 3. Variation of Hb concentration in the total population during the study

 
Hb concentrations were effectively maintained above 11 g/dl throughout the study period both after QW dosing (11.7 ± 0.8 g/dl), and Q2W dosing (11.7 ± 1.0 g/dl), with no statistically significant changes from the study outset or at the end of the study period (Figure 3) (P = 0.8). The percentage of evaluable patients who successfully maintained Hb concentrations in the required range was 65% [95% confidence interval (CI), 55–75%] for treatment period 1 and 81% (95% CI, 71–88%) for treatment period 2.


Figure 3
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  		Fig. 3. Mean (±SD) haemoglobin concentration overtime.

 
During dose adjustment, increases or decreases of darbepoetin alfa never exceeded 25% of the previous dose. There were no statistically significant differences in the mean weekly dose of i.v. darbepoetin alfa (34.0 ± 17.1 vs 32.1 ± 17.3 µg/week; P = 0.3) over the study period, even when adjusted for body weight [0.56 ± 0.36 vs 0.51 ± 0.33 µg/week; P = not significant (NS)] (Figure 4). The median weekly dose of darbepoetin alfa was 30.0 µg at the beginning of the study, at the end of treatment period 1 and at the end of treatment period 2, using both per-protocol and ITT analyses. Therefore, no difference was observed between the 80 patients who completed the study and the 105 patients who commenced the study.


Figure 4
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  		Fig. 4. Mean (±SD) weekly dose of darbepoetin alfa (µg/kg/week).

 
Mean serum ferritin levels were 443 ± 220 µg/l at the study outset and were maintained above 200 µg/l throughout the study period (565 ± 216 µg/l at the final evaluation). Intravenous iron was received by 90.5% (95/105) and 95.6% (86/90) of patients during treatment period 1 and 2, respectively (ITT population; P = NS). This is compared with 92.5% (74/80) and 96.3% (77/80) of patients, respectively, in the per-protocol population (P = NS). Mean doses of iron were 120 mg/month during treatment period 1 and 100 mg/month during treatment period 2 for both the ITT and per-protocol populations (P = NS).

Stability of Q2W darbepoetin alfa treatment
The stability of Hb concentrations for patients receiving Q2W darbepoetin alfa was determined in two ways: (i) the proportion of patients who did not require a switch back to QW administration of darbepoetin alfa and (ii) the proportion of patients receiving darbepoetin alfa who required a dose adjustment. Overall, 100% of patients (80/80) maintained the Q2W frequency. Of these patients, 26% (21/80) did not require any dose adjustments. Similarly, during the QW phase, 30% (24/80) of patients did not require any dose adjustments (P = NS).

Safety analysis
Darbepoetin alfa was well tolerated during the 1-year study period, consistent with previous clinical experience at the centre. No pure red-cell aplasia was reported in our study population. Adverse events were consistent with those typically found in the dialysis population and there were no differences observed between the two treatment periods. Overall, 67% of patients reported at least one adverse event. The most commonly occurring adverse events were hypertension (22%), arthralgia (12%), vascular access complication (11%), upper respiratory tract infection (10%), hypotension (9%), diarrhoea (7%) and asthenia (5%). None of the treatment-related adverse events led to study discontinuation for any of the patients.

C-reactive protein levels (mean ± SD 1.47 ± 1.87 and 0.91 ± 0.74 mg/dl in treatment periods 1 and 2, respectively) remained consistent throughout the study period, as did serum protein(s) (7.0 ± 0.42 and 6.9 ± 0.40 g/dl, respectively), parathyroid hormone (432 ± 195 and 383 ± 101 pg/ml, respectively) and Kt/V dosage (1.47 ± 0.34 and 1.46 ± 0.26, respectively). No significant differences in these laboratory parameters were observed between treatment periods 1 and 2.



   Discussion
Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
Acknowledgements
 References
 
It is now commonplace to administer ESAs to CKD patients with renal anaemia, regardless of their dialysis status, with less frequent administration than the regimens used immediately following their introduction in the 1980s [1]. This has occurred mostly from the practical use of such agents, but also with hindsight from large, randomized, clinical and controlled trials. As is the case in many areas of medicine, the results of in-clinic experience of less frequent administration of ESAs are rarely fully reported; thus the ability to administer ESAs at both reduced dosage and frequency remains a topic of continuing research and vigorous debate despite the plethora of published data showing the beneficial effects of ESAs in CKD patients, which has resulted in guidelines for their usage [1,2]. In our own unit, it has become regular practice to administer ESAs on dosing schedules less frequent than the initially approved three-times-per-week regimens used a decade ago. Our recent experience suggests not only can we routinely treat patients QW with ESAs, but that we can also obtain the same results and outcomes in patients administered Q2W with i.v. darbepoetin alfa. The results of our current investigation indicate clearly that switching CKD patients on HD from darbepoetin alfa QW to Q2W dosing effectively maintains stable Hb concentrations without any need for an increase in dose. However, we must place these results against the data currently published on other ESAs to further understand and maximize the benefits of reduced dosing in CKD patients, especially those receiving HD. The data for the use of i.v. rHuEPO at reduced frequency of QW in HD patients is largely anecdotal, limited and inconclusive, moreover, there are no studies or clinical reports for Q2W dosing regimen following i.v. rHuEPO administration.

The results of the present study fully support the practical use of the i.v. Q2W darbepoetin alfa regimen in stable HD patients switched from QW dosing. The fact that darbepoetin alfa can be administered less frequently to HD patients may offer considerable benefit to both patients and their healthcare providers, especially in view of the current recommended guidelines for i.v. administration of ESAs to dialysis patients [1].

If, as suggested from the present results, darbepoetin alfa can be given Q2W to CKD patients on HD, what does the future hold in terms of extended dosing frequency and adequacy? The area remains the subject of considerable research, but recent results suggest that it may be entirely feasible to administer darbepoetin alfa once monthly in order to maintain stable Hb concentrations in CKD patients. In one study [8], clinically stable dialysis patients (n = 38) receiving stable Q2W darbepoetin alfa were converted to darbepoetin alfa once every 3 weeks for 20 weeks, and then (if Hb concentrations were maintained between 10 and 13 g/dl) to darbepoetin alfa once monthly for a further 20 weeks. In another study [9], CKD patients (n = 97) not on dialysis receiving stable subcutaneous Q2W darbepoetin alfa were converted to darbepoetin alfa once monthly for 29 weeks. In both studies darbepoetin alfa administered once monthly effectively and safely maintained Hb levels in patients previously stabilised on Q2W dosing. Nevertheless, whatever the outcome of future clinical investigations, the present results from routine clinical practice confirm that Q2W administration of i.v. darbepoetin alfa is an effective and well-tolerated treatment in CKD patients on HD.



   Acknowledgements
Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 Acknowledgements
References
 
The authors would like to thank Dr Ana Macedo for her statistical analysis and Ms Rebecca Baker (English language assistant) and Ms Rosario Carvalho (Eurodial clinical secretary) for their help throughout the progress of the study.

The authors would also like to thank Gardiner-Caldwell Communications for their assistance in drafting the manuscript. Financial assistance to support this service was provided by Amgen.

Conflict of interest statement. F.C. is a scientific consultant for Amgen (Europe). None of the other authors have any conflict of interest to declare.



   References
Top
 Abstract
 Introduction
 Subjects and methods
 Results
 Discussion
 Acknowledgements
 References
 

  1. Locatelli F, Aljama P, Barany P, et al. for the European Best Practice Guidelines Working Group. (2004) Revised European Best Practice Guidelines for the mangement of anaemia in patients with chronic renal failure. Nephrol Dial Transplant 19:Suppl 2, 1–47.[Free Full Text]
  2. Aljama P, Bommer J, Canaud B, et al. for the NESP Usage Guidelines Group. (2001) Practical guidelines for the use of NESP in treating renal anaemia. Nephrol Dial Transplant 16:Suppl 3, 22–28.[Abstract/Free Full Text]
  3. Vanrenterghem Y, Barany P, Mann JF, et al. (2002) Randomized trial of darbepoetin alfa for treatment of renal anemia at a reduced dose frequency compared with rHuEPO in dialysis patients. Kidney Int 62:2167–2175.[CrossRef][Web of Science][Medline]
  4. Hörl WH, Holzer H, Mayer GJ. Osterreichische Aranesp Studiengruppe. (2002) [German] Treatment of renal anemia with darbepoetin alfa: results of an Austrian multicenter study. Wien Klin Wochenschr 114:967–971.[Web of Science][Medline]
  5. Martinez Castelao A, Reyes A, Valdes F, et al. (2003) [Spanish] Multicenter study of darbepoetin alfa in the treatment of anemia secondary to chronic renal insufficiency on dialysis. Nefrologia 23:114–124.[Web of Science][Medline]
  6. Del Vecchio L, Villa G, Carraro G, et al. Gruppo Di Studio NESP 2000 0116 (NESP 3b). (2004) [Italian] Italian study on the treatment of anaemia in chronic dialysis patients switched over to less frequent doses of darbepoetin from human recombinant erythropoietin (rHuEPO). G Ital Nefrol 21:259–266.[Medline]
  7. Cruz J, Barata JD, Pais MJ. e o gruppo de trabalho do estudo Aranesp – 20000118. (2002) [Portuguese] Efficacy and safety of darbepoetin alfa in ESRD patients – Portuguese Multicentre Study. Rev Port Nefrol Hipert 16:137–150.
  8. Jadoul M, Vanrenterghem Y, Foret M, Walker R, Gray SJ. (2004) Darbepoetin alfa administered once monthly maintains haemoglobin levels in stable dialysis patients. Nephrol Dial Transplant 19:898–903.[Abstract/Free Full Text]
  9. Ling B, Walczyk M, Agarwal A, Carroll W, Liu W, Brenner R. (2005) Darbepoetin alfa administered once monthly maintains hemoglobin concentrations in patients with chronic kidney disease. Clin Nephrol 63:327–334.[Web of Science][Medline]
Received for publication: 17. 3.06
Accepted in revised form: 8. 6.06


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