Open Access

Effect of long-acting erythropoiesis-stimulating agents on hemoglobin levels at the initiation of dialysis

  • Takasuke Asakawa1,
  • Yasuhiro Komatsu7,
  • Ryoichi Ando3,
  • Nobuhiko Joki1Email author,
  • Yuri Tanaka1,
  • Masaki Iwasaki1,
  • Hiroki Hase1,
  • Masato Ikeda2,
  • Daijo Inaguma5,
  • Toshifumi Sakaguchi10,
  • Toshio Shinoda4,
  • Fumihiko Koiwa8,
  • Shigeo Negi6,
  • Toshihiko Yamaka9 and
  • Takashi Shigematsu6
Renal Replacement Therapy20162:12

https://doi.org/10.1186/s41100-016-0018-2

Received: 25 June 2015

Accepted: 2 November 2015

Published: 22 February 2016

Abstract

Background

The goal of the present study was to explore the differences in effects between erythropoiesis-stimulating agent (ESA) types on hemoglobin (Hb) level at the initiation of maintenance dialysis.

Methods

This was a cross-sectional study. From January 2006 to October 2012, 2920 patients with end-stage kidney disease commenced hemodialysis (HD) at nine participating hospitals. The criteria for exclusion from the database were (1) presence of cancer or gastrointestinal bleeding and (2) serum C-reactive protein ≥0.3 mg/dL. A total of 1263 patients were entered into the final database. We explored the association of yearly trend of Hb level just before the first HD session with the different types of ESA in the predialysis period.

Results

During the 7-year study period, patients’ Hb levels at the initiation of dialysis dramatically increased from 8.6 to 9.1 g/dL. Parallel to this increase, the use of long-acting ESA also increased from 0 to 80 %. A higher level of Hb was confirmed in the long-acting ESA group compared with the short-acting group (9.5 vs. 8.7 g/dL, P < 0.01). Multivariate regression analysis showed a strong association of Hb level with the use of long-acting ESA (r = 0.155, P = 0.003), even after adjusting for confounding variables and estimated dose of epoetin.

Conclusions

The change in the type of ESA used from short-acting to long-acting played a role in the increase of patients’ Hb levels at the initiation of dialysis. A long-acting ESA has the potential effect of maintaining an optimal Hb level even in the advanced stages of CKD.

Keywords

Hemoglobin Erythropoiesis-stimulating agents Long-acting Initiation of dialysis

Background

Anemia plays a crucial role in the promotion of cardiac remodeling and, consequently, in the onset of cardiac events in patients with chronic kidney disease (CKD) [1, 2]. This is the reason why vigorous debate continues in the search for an optimal target hemoglobin (Hb) level, achieved by treatment with an erythropoiesis-stimulating agent (ESA) for preventing cardiac abnormalities and events in the predialytic phase of CKD [3]. Unfortunately, even among CKD patients who receive ESA therapy, a higher percentage of anemia, with Hb levels <11 g/dL, is observed in patients in the more advanced stages of CKD [4]. Indeed, previous data from our multicenter study of Japanese dialysis patients clearly revealed that the mean Hb level at the initiation of dialysis was 8.5 g/dL [5], which is lower than the target level recommended by current international guidelines [68]. It is also known that the onset of cardiac events such as congestive heart failure and myocardial ischemia increase close to the time of initiation of dialysis [9, 10]. Although the evidence is still limited, we are assuming that this progression of anemia plays, at least in part, a role in the occurrence of cardiac events in the advanced stages of CKD. The occurrence of cardiac remodeling and events may decrease or become less severe if the Hb level could be kept at an optimum level—that is, over 10 g/dL—even at the initiation of dialysis.

Recently, the newer generation of ESAs has been changing to the long-acting type, such as darbepoetin and continuous erythropoietin receptor activators (CERA), rather than epoetin-α and -β. Referring to the dose conversion ratio from darbepoetin to epoetin [11], a higher prescribing dose of epoetin in the predialytic phase of CKD is theoretically more feasible than before. However, the evidence is still limited about the effect of long-acting ESAs on anemia in the advanced stages of CKD. The use of long-acting ESAs could increase the Hb level in the advanced stages of CKD. The goal of the present study was to explore the association of the yearly trend of mean Hb level with the change in the type of ESA used at the initiation of renal replacement therapy (RRT) during 2006–2012. Our hypothesis is that Hb level at the initiation of dialysis has increased after the introduction of the long-acting ESAs into the clinical practice compared with before their approval of clinical use.

Methods

Study design and patients

We conducted a retrospective study for cross-sectional comparative analysis of patients with ESKD among different eras by using the database of the Japanese Study Group for Assessing Initiation of Renal Replacement Therapy (J-START), which includes the nephrology units of nine teaching hospitals in Japan. The objective of J-START is to create a shared database on end-stage kidney disease (ESKD) patients at the time of starting RRT for the conduct of clinical research. From January 2006 to October 2012, there were 2920 ESKD patients who commenced chronic hemodialysis (HD) at the nine hospitals. Clinical information on those patients was added to the J-START database. In order to explore the precise effect of ESAs on anemia, the ESKD patients with major etiological factors for low responsiveness to ESA [8] were excluded. The following exclusion criteria were employed: (1) gastrointestinal bleeding or other bleeding disease (n = 40), (2) cancer (n = 159), and (3) inflammation, with serum C-reactive protein (CRP) level >0.3 mg/dL (n = 1458), such as in infectious disease or autoimmune disease. As a result, 1263 ESKD patients were available for inclusion in the database of this study. We explored the association of the yearly trend of the Hb levels just before patients’ first HD session with the change of ESA type in the predialysis period. The clinical factors associated with Hb level were also explored.

The ethics committee for clinical research of Toho University Ohashi Medical Center approved the study protocol [permission No. 13-52, 13-61]. This study adhered to the Declaration of Helsinki. Informed consents to participate in this study and for the publication were obtained from all participants.

Data collection

Using the study protocol, clinical information was recorded for all patients at each nephrology unit immediately prior to their first HD session. Information was also collected on the use of oral medications and ESA per month during the predialysis period. Blood pressure (BP) was recorded in the supine position, and a blood sample was collected just before the first HD session. The comorbid conditions at the initiation of dialysis were reviewed from the medical records. The Hb was corrected by dose of ESA/1000 units. The estimated glomerular filtration rate (eGFR) was calculated by using the new Japanese equation [12]: eGFR (mL/min/1.73 m2) = 194 × Cr−1.094 × age−0.287 (×0.739 for women). Body mass index (BMI) at optimal weight was calculated as the weight in kilograms divided by the square of the height in meters. Patients with “vascular access” were the patients for whom an arterio-venous fistula was surgically created according to a planned schedule before initiation of dialysis. Standard chest radiography proceeded on the day of the first HD session. The cardiothoracic ratio (CTR) was determined by dividing the maximal horizontal width of the heart by the horizontal inner width of the rib cage. Medications were classified as ESA, angiotensin-converting enzyme inhibitors (ACE-I), angiotensin-II receptor blockers (ARB), vitamin D, iron agents, and AST-120. AST-120 is a carbonaceous adsorbent that is used to treat CKD patients in Japan. It has been reported that AST-120 removes uremic toxins and reduces oxidative stress [13, 14]. The duration of nephrologist care was defined as the length of follow-up days by nephrologists prior to the initiation of HD.

ESA type

In Japan, epoetin-α and -β have been approved for use during the predialytic phase of CKD since 1995. Darbepoetin-α and methoxy polyethylene glycol-epoetin β (Continuous Erythropoietin Receptor Activator; CERA) were registered in 2010 and 2011 respectively, all for use during the predialytic phase of CKD. Epoetin-α and -β are short-acting ESAs, and darbepoetin-α and CERA are long-acting ESAs. The dose conversion ratios from darbepoetin-α and CERA to epoetin α/β were used 1:200 [15] and 1:270 [16] respectively.

Statistical analysis

Data are expressed as the mean ± SD, median [interquartile range], or percentage. Subject characteristics were compared across CKD stages using chi-square tests for categorical variables, analysis of variance (ANOVA) for normally distributed variables, and Kruskal-Wallis tests for non-normally distributed variables. As appropriate, the Jonckheere-Terpstra trend test was used for assessing the yearly trend of Hb concentration. To assess the association of various factors with Hb level, Spearman univariate regression analysis was employed. Dummy variables were used for gender (0 for female, 1 for male), primary renal disease (0 for non-diabetic nephropathy, 1 for diabetic nephropathy), smoking history (0 for negative, 1 for positive), and each medication (0 for not used, 1 for used). Dummy variables were also used for type of ESA (0 for short-acting ESA, 1 for long-acting ESA). The monthly ESA dose was evaluated as a numerical factor. The dose was also divided by 1000 units for analysis as appropriate. Multivariate regression analysis was also performed to identify independent determinants of Hb concentration. In all analyses, a probability (P) value <0.05 was considered statistically significant. All statistical analyses were performed using SPSS for Windows version 20 (IBM, New York, USA).

Results

Patient characteristics

The mean age of the entire group of study subjects was 64.5 ± 14.0 years. The percentage of men (64.6 %) and the percentage of patients with diabetic nephropathy (43.8 %) were similar to the percentages previously reported at the initiation of dialysis for the entire Japanese dialysis population [17]. The mean serum creatinine (Cr) and eGFR at the initiation of renal replacement therapy (RRT) were 9.5 ± 3.3 mg/dL and 5.2 ± 2.2 mL/min/1.73 m2, respectively, which were similar to the levels for the Japanese dialysis population [17]. Therefore, our subjects seemed to constitute a suitable sample of Japanese dialysis patients. The mean Hb level was 8.8 ± 1.5 g/dL, and the median monthly estimated dose of epoetin just before the initiation of HD was 12,000 units per month. Other clinical characteristics are shown in the first column of Table 1.
Table 1

The characteristics of the study patients and temporal trends for 7 years

 

Total

2006

2007

2008

2009

2010

2011

2012

p value

Patients number

1263

195

162

210

184

188

189

135

 

Age, years

64.5 ± 14.0

60.2 ± 14.8

63.5 ± 12.9

63.5 ± 14.1

65.9 ± 14.1

64.8 ± 13.5

67.8 ± 13.3

66.6 ± 13.9

.000

Male, %

65

65

65

68

63

68

60

64

.722

Diabetes, %

46

50

48

43

51

44

42

45

.517

BMI, kg/m2

23.1 ± 4.7

22.6 ± 5.5

23.1 ± 3.9

22.7 ± 3.4

23.1 ± 4.5

23.7 ± 6.4

22.9 ± 4.6

23.8 ± 4.2

.212

Duration of nephrologist care, days

625

552

432

608

566

697

796

775

.109

[174, 1557]

[83, 1789]

[175, 1450]

[185, 1346]

[138, 1356]

[160, 1860]

[206, 1530]

[254, 1827]

Vascular access, %

70

68

70

70

69

68

68

77

.615

Primary disease, %

.000

Diabetic nephropathy

44

47

48

42

47

43

40

40

 

Glomerulonephritis

21

31

17

25

15

18

18

23

 

Nephrosclerosis

16

7

17

10

19

19

25

22

 

PCK

4

2

5

4

3

5

5

2

 

Others

16

14

14

20

17

16

13

13

 

Systolic BP, mmHg

155 ± 25

152 ± 25

159 ± 24

154 ± 25

153 ± 26

155 ± 25

154 ± 23

156 ± 25

.222

Diastolic BP, mmHg

78 ± 14

77 ± 13

80 ± 14

79 ± 13

76 ± 14

79 ± 14

78 ± 14

81 ± 14

.067

CTR, %

53.3 ± 6.7

52.6 ± 6.5

53.9 ± 6.3

53.4 ± 6.9

53.7 ± 6.6

53.5 ± 6.4

52.9 ± 7.9

53.2 ± 6.2

.659

Hemoglobin, g/dL

8.7 ± 1.5

8.5 ± 1.6

8.6 ± 1.3

8.6 ± 1.6

8.7 ± 1.4

8.6 ± 1.5

9.0 ± 1.5

9.1 ± 1.4

.002

Hemoglobin/dose of ESAa

0.46

0.48

0.43

0.43

0.58

0.58

0.46

0.40

.050

[0.35, 0.72]

[0.35, 0.71]

[0.35, 0.70]

[0.35, 0.69]

[0.38, 0.77]

[0.38, 0.73]

[0.33, 0.76]

[0.27, 0.73]

Albumin, g/dL

3.3 ± 0.5

3.3 ± 0.5

3.3 ± 0.5

3.4 ± 0.5

3.3 ± 0.5

3.3 ± 0.5

3.4 ± 0.5

3.4 ± 0.5

.153

Creatinine, mg/dL

9.4 ± 3.2

9.8 ± 3.8

9.7 ± 3.5

9.1 ± 2.9

9.4 ± 3.2

9.1 ± 3.1

9.3 ± 3.1

9.6 ± 3.0

.228

eGFR, mL/min/1.732

5.1 ± 2.2

5.2 ± 2.2

5.0 ± 1.9

5.4 ± 2.1

5.2 ± 2.9

5.3 ± 1.8

5.0 ± 1.9

4.8 ± 1.9

.280

Total cholesterol, mg/dL

172 ± 50

177 ± 53

180 ± 53

170 ± 47

170 ± 42

169 ± 56

171 ± 52

168 ± 44

.401

Triglyceride, mg/dL

111

113

110

106

114

103

126

109

.272

[81, 157]

[80, 156]

[79, 167]

[79, 201]

[81, 152]

[76, 161]

[88, 163]

[83, 149]

HDL-C, mg/dL

48 ± 16

49 ± 18

50 ± 19

48 ± 15

46 ± 14

49 ± 17

49 ± 16

46 ± 15

.223

Calcium, mg/dL

7.8 ± 0.9

7.8 ± 1.0

7.8 ± 1.0

7.9 ± 0.9

7.8 ± 0.9

7.8 ± 0.9

8.0 ± 0.9

7.8 ± 0.9

.092

Phosphate, mg/dL

6.1 ± 1.6

6.1 ± 1.6

5.9 ± 1.5

5.9 ± 1.4

6.1 ± 1.7

6.1 ± 1.5

6.0 ± 1.6

6.4 ± 1.5

.045

Ca x P product

47 ± 13

47 ± 13

46 ± 13

46 ± 12

46 ± 14

47 ± 12

48 ± 14

49 ± 15

.260

i-PTH, pg/mL

271

210

264

300

285

272

266

331

.000

[169, 414]

[141, 346]

[179, 382]

[170, 425]

[185, 416]

[171, 426]

[159, 393]

[188, 468]

CRP, mg/dL

0.10

0.10

0.10

0.10

0.08

0.10

0.10

0.13

.000

[0.04, 0.17]

[0.04, 0.15]

[0.0, 0.14]

[0.0, 0.13]

[0.02, 0.10]

[0.02, 0.20]

[0.05, 0.20]

[0.05, 0.20]

Glucose, mg/dL

137 ± 52

142 ± 61

144 ± 61

135 ± 47

136 ± 53

137 ± 49

130 ± 47

139 ± 44

.243

Fe, μg/dL

67 ± 35

66 ± 36

64 ± 31

69 ± 33

68 ± 33

70 ± 37

66 ± 35

66 ± 39

.772

TIBC, μg/dL

233 ± 46

229 ± 46

239 ± 41

236 ± 51

229 ± 49

230 ± 48

231 ± 42

236 ± 43

.352

Ferritin, ng/dL

117

117

111

141

110

124

126

101

.309

[57, 209]

[61, 199]

[56, 194]

[68, 232]

[51, 114]

[57, 225]

[56, 213]

[42, 187]

ESA, %

78

81

74

77

79

79

80

80

.810

long-acting ESA, %

15

0

0

0

0

2

49

80

.000

Dose of ESA, per month

12,000

12,000

12,000

24,000

12,000

12,000

24,000

24,000

.001

[12,000, 24,000]

[12,000, 24,000]

[12,000, 24,000]

[12,000, 24,000]

[12,000, 24,000]

[12,000, 24,000]

[12,000, 24,000]

[12,000, 33,000]

ARB/ACE-I, %

64

56

67

69

61

70

65

61

.051

Vitamin D, %

31

26

34

271

23

36

32

41

.007

AST-120, %

19

17

18

27

19

19

16

14

0.054

Iron, %

19

31

18

20

18

14

23

19

.403

Data are expressed as the mean ± SD, median [interquartile range], or percentage

BMI body mass index, PCK polycystic kidney disease, BP blood pressure, CTR cardiothoracic ratio, eGFR estimated glomerular filtration rate, HDL-C high density lipoprotein, i-PTH intact parathyroid hormone, CRP C-reactive protein, TIBC total iron-binding capacity, ESA erythropoiesis-stimulating agents, ARB angiotensin receptor blocker, ACE-I angiotensin-converting enzyme inhibitor

aHemoglobin was corrected by dose of ESA per 1000units

Yearly trend of patient characteristics

We examined changes in the clinical features of the study patients during the study period (2006–2012). Age increased over time from 60 to 67 years (P < 0.001 for trend). The Hb level dramatically increased over time (P < 0.001 for trend) from 8.6 to 9.1 g/dL. In particular, as shown in Fig. 1, the rise in the Hb level was confirmed during 2011 and 2012, along with a significant and parallel increase in the proportion of usage of long-acting ESAs (Fig. 2). The concentrations of iron, total iron-binding capacity (TIBC), and ferritin did not show any significant changes during the 7-year study period. The ratio of iron medicine users increased during the last 2 years, in 2011 and 2012.
Fig. 1

The concentration of Hb dramatically increased over time (P < 0.001 for trend) from 8.6 to 9.1 g/dL in the 7-year study period. The remarkable increase in Hb level was confirmed between 2010 and 2011, along with a significant and parallel increase in the proportion of use of long-acting ESA

Fig. 2

The grouped bar graph depicts the yearly trend of the proportion of ESA. The use of long-acting ESA (gray bar) significantly increased in last 2 years of the study, 2011 and 2012 (P < 0.001 for trend). About 20 % of the patients did not use ESA (black bar) in any calendar year. White bar means percentage of patients with short-acting ESA

Differences in Hb level and clinical characteristics between ESA types

The comparison of the Hb level between the three patient groups (long-acting ESA users, short-acting ESA users, and non-ESA users) is shown in Fig. 3. The Hb level of the patients in the long-acting ESA group was significantly higher than the Hb levels of the short-acting ESA group and the non-ESA group. No significant difference was observed between the non-ESA users and the short-acting ESA users. The other clinical characteristics in three patient groups are shown in Table 2. Some tendencies between three patient groups are seen in the Table. Older, longer duration of nephrologist care, higher albumin level, lower eGFR, and higher usage of vitamin D were found in ESKD patients with long-acting ESA compared with those of the other two groups.
Fig. 3

The Hb level of patients who received long-acting ESA was significantly higher than in the patients who received no ESA (P < 0.001) or short-acting ESA (P < 0.001). There was no significant difference in Hb levels between the non-ESA and short-acting ESA patient groups

Table 2

The characteristics of 3 patient groups, non-ESA, ESA-short, and ESA-long

 

Non-ESA

Short-acting ESA

Long-acting ESA

p value

Patients number

271

788

204

 

Age, years

63.8 ± 14.9

64.2 ± 13.7

67.0 ± 13.9

.021

Male, %

66

65

61

.546

Diabetes, %

47

47

44

.800

BMI, kg/m2

22.3 ± 5.8

23.3 ± 4.5

23.3 ± 4.0

.016

Duration of nephrologist care, days

117 [5, 923]

715 [281, 1723]

872 [307, 1748]

.000

Vascular access, %

46

74

86

.000

Diabetic nephropathy

44

45

39

.404

Systolic BP, mmHg

158 ± 25

154 ± 25

154 ± 25

.070

Diastolic BP, mmHg

82 ± 15

78 ± 14

80 ± 15

.000

CTR, %

55 ± 8

53 ± 6

53 ± 6

.002

Hemoglobin, g/dL

8.6 ± 1.6

8.7 ± 1.5

9.5 ± 1.4

.000

Hemoglobin/dose of ESAa

-

0.51 [0.36, 0.73]

0.40 [0.28, 0.72]

.000

Albumin, g/dL

3.3 ± 0.6

3.4 ± 0.6

3.5 ± 0.5

.002

Creatinine, mg/dL

8.9 ± 3.4

9.6 ± 3.3

9.6 ± 3.1

.012

eGFR, mL/min/1.732

5.7 ± 3.0

5.1 ± 1.9

4.9 ± 2.0

.000

Total cholesterol, mg/dL

186 ± 64

172 ± 47

162 ± 44

.000

Triglyceride, mg/dL

122 [84, 182]

109 [78, 154]

110 [83, 150]

.082

HDL-C, mg/dL

50 ± 19

49 ± 17

47 ± 16

.473

Calcium, mg/dL

7.8 ± 1.1

7.9 ± 1.0

8.0 ± 1.0

.013

Phosphate, mg/dL

6.3 ± 1.8

6.0 ± 1.5

6.3 ± 1.6

.010

Ca x P product

47 ± 16

47 ± 12

49 ± 15

.067

i-PTH, pg/mL

291 [171, 421]

265 [168, 403]

291 [168, 446]

.176

CRP, mg/dL

0.10 [0.05, 0.17]

0.10 [0.02, 0.13]

0.14 [0.04, 0.20]

.000

glucose, mg/dL

132 ± 55

140 ± 52

138 ± 50

.156

Fe, μg/dL

72 ± 36

67 ± 34

65 ± 38

.167

TIBC, μg/dL

231 ± 56

233 ± 45

236 ± 43

.644

Ferritin, ng/dL

140 [73, 282]

117 [57, 204]

105 [49, 193]

.077

Dose of ESA, per month

0

12,000 [12,000, 24,000]

24,000 [12,000, 36,000]

.000

ARB/ACE-I, %

56

67

65

.003

Vitamin D, %

21

31

44

.000

AST-120, %

9

22

18

.000

Iron, %

10

21

23

.001

Data are expressed as the mean ± SD, median [interquartile range], or percentage

BMI body mass index, BP blood pressure, CTR cardiothoracic ratio, eGFR estimated glomerular filtration rate, HDL-C high density lipoprotein, i-PTH intact parathyroid hormone, CRP c-reactive protein, TIBC total iron-binding capacity, ESA erythropoiesis-stimulating agents, ARB angiotensin receptor blocker, ACE-I angiotensin-converting enzyme inhibitor

aHemoglobin was corrected by dose of ESA per 1000units

Univariate regression analysis determined the factors associated with Hb

Among the clinical characteristics, planned vascular access, serum albumin, eGFR, total cholesterol, Ca, TIBC, long-acting ESA use, and estimated long-acting ESA dose were significantly correlated with Hb level, as shown in Table 3. Significant negative associations were observed between Hb and CTR and serum phosphate level.
Table 3

Univariate linear regression analysis for the factors associated with Hb level

 

Regression coefficient

95 % CI

P

Age, years

.036

−0.002

.010

.195

Male

.047

−0.023

.320

.089

Diabetes

.059

.014

.343

.033

BMI

.018

−0.024

.012

.524

Duration of nephrologist care

.013

.000

.000

.655

Vascular access

.151

.320

.674

.000

Diabetic nephropathy

.026

−0.112

.039

.339

Systolic BP

.014

−0.004

.002

.622

Diastolic BP

.048

−0.001

.011

.090

CTR

.157

−0.05

−0.022

.000

Albumin

.176

.330

.619

.000

Creatinine

.162

−0.1

−0.05

.278

eGFR

.187

.090

.163

.000

Total cholesterol

.11

.001

.005

.000

Triglyceride

.074

.000

.003

.013

HDL-C

.040

−0.002

.009

.188

Calcium

.201

.223

.383

.000

Phosphate

.088

−0.134

−0.032

.001

Ca x P product

.020

−0.004

.008

.467

i-PTH

.049

−0.001

.000

.113

C-reactive protein

.002

−1.087

1.016

.948

Glucose

.016

−0.001

.002

.585

Fe

.068

.000

.005

.021

TIBC

.087

.001

.005

.003

Ferritin

.074

−0.001

.000

.013

ESAa

.031

−.079

.285

.268

Long-acting ESAb

.205

0.524

0.967

.000

Dose of ESA, per 1000 units

.075

.002

.019

.015

ARB/ACE-I

.019

−0.113

.233

.497

Vitamin D

.020

−0.12

0.253

.484

AST-120

.017

−0.148

.275

.554

Iron

.000

−0.176

.176

.999

BMI body mass index, BP blood pressure, CTR cardiothoracic ratio, eGFR estimated glomerular filtration rate, HDL-C high density lipoprotein, i-PTH intact parathyroid hormone, CRP c-reactive protein, TIBC total iron-binding capacity, ESA erythropoiesis-stimulating agents, ARB angiotensin receptor blocker, ACE-I angiotensin-converting enzyme inhibitor

aDummy variables was used for usage of any type of ESA (0 for not used, 1 for used)

bDummy variables was used for type of ESA (0 for short-acting ESA, 1 for long-acting ESA)

Independent association of long-acting ESA with Hb

Table 4 presents the independent association of long-acting ESA use and its estimated dose with Hb. Dummy variables were used for type of ESA (0 for short-acting ESA, 1 for long-acting ESA). The positive association of long-acting ESA use with Hb remained significant after adjustment for age, gender, diabetes, BMI, systolic BP, vascular access, duration of nephrologist care, CTR, and estimated long-acting ESA dose as shown in model 2. This was true even after further adjustment for markers of malnutrition and inflammation (albumin and CRP), markers of lipid and glucose metabolism (total cholesterol, triglycerides, high-density lipoprotein (HDL)-C, and glucose), markers of calcium phosphate metabolism (calcium, phosphate, intact parathyroid hormone, use of vitamin D), markers for iron metabolism (Fe, TIBC, ferritin, use of iron agent), and medications (use of ACE-I/ARB, AST-120) as shown in models 3 through 7. Finally, as shown in model 8, the independent association of long-acting ESA with Hb was confirmed by multiple linear regression analysis, including all markers of models 2 to 7. On the other hand, no significant associations of Hb level with estimated long-acting ESA dose were observed in all models of multiple linear regression analysis including long-acting ESA use.
Table 4

Independent association of use and dose of long-acting ESA with Hb level by multiple linear regression analysis

Model

Adjustment

 

Regression coefficient

95 % CI

P

Model 1a

Unadjusted

Long-acting ESA

0.204

0.515

1.02

.000

Dose of ESA/1000 units

0.024

−0.007

0.014

.483

Model 2b

Age, sex, diabetes, BMI, SBP, vascular access, nephrologists care, CTR

Long-acting ESA

0.191

0.427

0.976

.000

Dose of ESA/1000 units

−0.019

−0.014

0.008

.613

Model 3c

Model 2 + albumin, CRP

Long-acting ESA

0.169

0.341

0.912

.000

Dose of ESA/1000 units

−0.013

−0.013

0.009

.721

Model 4d

Model 2 + TC, TG,HDL-C, Glu

Long-acting ESA

0.196

0.41

1.039

.000

Dose of ESA/1000 units

−0.023

−0.017

0.01

.588

Model 5e

Model 2 + Ca, P, iPTH, vitamin D

long-acting ESA

0.186

0.388

0.948

.000

Dose of ESA/1000 units

−0.022

−0.015

0.008

.570

Model 6f

Model 2 + Fe, TIBC, ferritin, iron tx

Long-acting ESA

0.168

0.275

0.848

.000

Dose of ESA/1000 units

−0.029

−0.018

0.009

.503

Model 7g

Model 2 + ACEI/ARB, AST-120

Long-acting ESA

0.188

0.411

0.962

.000

Dose of ESA/1000 units

−0.016

−0.014

0.009

.683

Model 8h

All

Long-acting ESA

0.155

0.176

0.858

.003

Dose of ESA/1000 units

−0.029

−0.019

0.01

.555

aUnadjusted

bAdjusted for age, sex, diabetes nephropathy, BMI, SBP, vascular access, duration of nephrologists care, and CTR

cAdjusted for variables in model 2 plus albumin and CRP

dAdjusted for variables in model 2 plus total cholesterol, triglyceride, high lipoprotein cholesterol, and glucose

eAdjusted for variables in model 2 plus calcium, phosphate, and intact-PTH

fAdjusted for variables in model 2 plus Fe, TIBC, ferritin, and usage of iron medication

gAdjusted for variables in model 2 plus usage of angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, and AST-120

hAdjusted for all variables from model 2 to 7

Association of long-acting ESA with categorical Hb levels

For real world clinical implication, multiple logistic regression analysis was performed to identify the association of long-acting ESA with categorical Hb levels by using dummy variables, 0 for short-acting ESA, 1 for long-acting ESA. As shown in Table 5, higher level of categorical Hb level was more associated with the use of long-acting ESA compared with reference category of Hb 8.0–8.9 after adjusted by age, sex, BMI, diabetes, albumin, eGFR, and CRP. No significant associations were observed between categorical Hb level less than 8.0 and use of long-acting ESA.
Table 5

Independent association of categorical Hb level with using of long-acting ESAa

Hemoglobin, g/dL

Odds ratio

95 % CI

p

<7.0

0.673

0.302–1.502

.334

7.0–7.9

0.858

0.476–1.548

.611

8.0–8.9

1

  

9.0–9.9

2.218

1.349–3.646

.002

10.0–10.9

2.844

1.652–4.896

.000

≥11.0

3.102

1.596–6.031

.001

aAdjusted by age, sex, BMI, diabetes, albumin, eGFR, and CRP

Discussion

Main findings of current study

Based on the registry data of Japanese dialysis patients from nine hospitals, the mean Hb level at the initiation of dialysis is 8.5 g/dL, which is much lower than the optimal Hb level recommended by international guidelines [68]. It remains unclear whether the change of ESA type has exerted an advantageous effect on the Hb level at the initiation of maintenance dialysis. Our present multicenter study clearly showed three important findings: (1) Hb level at the initiation of dialysis has dramatically increased in the past 2 years (2011 and 2012) compared with the Hb levels from 2006 to 2010; (2) parallel with this trend, the main type of ESA used has drastically changed from short-acting such as epoetin α/β to long-acting such as darbepoetin-α and CERA between 2010 and 2011; and (3) the use of long-acting ESA was strongly and independently associated with Hb level in our study subjects. These findings suggest that long-acting ESAs (darbepoetin-α and CERAs) could help CKD patients maintain their Hb near the optimal level even in a severely uremic state, which is one of the strongest causes of ESA-resistant anemia.

Assessment of the effects of long-acting ESA on Hb level

The ability to use a higher dosage of epoetin could explain the beneficial effect of long-acting ESA on Hb. Based on the instructions for the use of long-acting ESA in the drug package insert, and referring to the recommended dose conversion ratio from darbepoetin or CERA to epoetin [15, 16], we can theoretically prescribe an approximately 1.5 times higher monthly estimated dose of epoetin in the predialytic phase of CKD. In Japan, max monthly dosage of epoetin-α or -β is 24,000 IU in predialytic phase of CKD patients. For darbepoetin-α and CERA, max monthly dosages are 240 and 250 μg, respectively. Based on the dose conversion ratio to epoetin 200:1 for darbepoetin and 270:1 for CERA, at least one-half dosage of estimated epoetin was applicable to CKD patients. Indeed, as shown in Table 1, an estimated dose of epoetin 1.5 times higher was administered to the patients after 2011 compared with before 2010. It is thought that the switch from a short-acting to a long-acting ESA increases the available estimated dose of epoetin, and consequently, the Hb level at the initiation of dialysis.

Iron status is one of the important parts for the optimal treatment of anemia in ESKD patients. The difference of iron utilization could play some role more increasing of Hb level in patients with long-acting ESA than those of short-acting ESA. Actually, it is reported that difference of type of ESA [18] or difference of administration interval of ESA [19] make a changing of iron status favorably for treatment of anemia in ESKD patients. However, any remarkable differences did not exist between two patients group with long-acting ESA and short-acting ESA in the marker of iron status such as iron, ferritin, TSAT, and usage of iron agents. Therefore, it is not likely that the status and utilization of iron play some role for increasing Hb level in long-acting ESA in this study.

Another possibility is that, independent of dose, the potential direct effect of a long-acting ESA could play a role in the elevation of Hb level at the initiation of dialysis. On multiple regression analysis, use of long-acting ESA was more closely associated with Hb level than its estimated dose from the conversion ratio in our study. Several studies have suggested that the conversion ratio from epoetin to darbepoetin-α of 1:350 in the clinical setting is higher than the fundamental conversion ratio from the molecular structure of 1:200 [15, 20]. This might mean that darbepoetin-α has a potentially more powerful effect on increasing the Hb than we expected. Further study is needed to prove this issue.

Many clinical factors are thought to affect the Hb level at the initiation of dialysis. Residual renal function is thought to be the biggest contributor to Hb levels in CKD patients. It is well known that a positive relationship exists between endogenous erythropoietin concentration and the serum eGFR [21] in CKD patients. The present study was conducted by using a combined database from nine hospitals. The question arises of whether the policy and indication for starting dialysis are not standardized, but rather, are at each physician’s discretion. This could make a difference in the timing for starting dialysis, and, consequently, influence the Hb concentration at the initiation of dialysis. Therefore, in order to minimize this bias, multivariate regression analysis was performed to adjust for confounding variables, including renal function. After adjusting by serum creatinine level or eGFR, the positive association of long-acting ESA with Hb level remained statistically significant. Also, after simultaneously adjusting for other factors, as seen in Tables 4 and 5, the use of long-acting ESA was well-associated with Hb concentration. These findings imply that long-acting ESA plays a beneficial role in maintaining a higher Hb concentration than short-acting ESA. The reason is probably the higher estimated epoetin dose or other potential effect. We would like to emphasize that excluding the patients with suspicion of low responsiveness to ESA could lead an anticipating results.

Limitations

A major limitation of the present study was the study design. A cross-sectional study design cannot be used to prove clear any causal effect of ESA on Hb level. The data available to us concerning ESA covered only the dosage in the month immediately before the initiation of dialysis. No information about the duration of ESA treatment existed in our database. To minimize such bias, we attempted to perform multivariate analysis including the factors “Duration of nephrologist care before initiation of dialysis” and “vascular access.” These two factors may be markers of CKD patients’ adaptation to dialysis, the patients’ compliance with their nephrologists’ care plans, and the degree of patient education received by the patients. After adjusting for these two markers, the association of long-acting ESA with Hb remained statistically significant. These results suggest that long-acting ESA could increase the Hb level in the advanced stages of CKD even in a relatively short duration of treatment. Another limitation of the present study is that the target Hb level may be not consistent among doctors or hospitals. However, we do have confirmed with all the members of J-START that management of anemia in the predialytic phase was performed essentially based on the Japanese guidelines published in 2004 and 2008 [8, 22]. Especially, from 2008, we changed the management of anemia to a protocol based on the Japanese guidelines [8]. The target Hb levels for non-dialyzed patients were almost the same in both guidelines from 11 to 12 g/dL. Third, we have a look at the trend for decreasing of percentage of diabetic nephropathy, which is different from those of western countries. This difference could make an advantage to our finding. However, even including diabetic nephropathy in multivariate analysis, our main finding that the positive association of long-acting ESA use with Hb was observed remained significant. Therefore, we believe that the bias has no big influence to our results. Fourth, about 50 % of ESKD patients showed CRP level over 0.3 mg/dL and were excluded from our study. As we described in the method area, blood sample data in this study was collected just before the first HD session. Advanced uremic state can lead to non-infected chronic inflamed state. Also, uremic state would be the cause of immune dysfunction consequently susceptible to infectious disease. Based on these assessments, it is reasonable to find that about 50 % of ESKD patients at the initiation of dialysis showed CRP level over 0.3 mg/dL on the blood sampling just before the first HD session. Actually, DOPPS study [23] demonstrated that median CRP level of 1392 Japanese stable chronic hemodialysis patients is 0.1 mg/dL with interquartile range from 0.05 to 0.31 mg/dL. This means that about 25 % of patients showed CRP level over 0.3 mg/dL even in stable dialysis patients.

Conclusions

The use of long-acting ESAs such as darbepoetin-α and CERA elevates the Hb level in the advanced stages of CKD. This effect might be mainly due to the ability to use a higher estimated dose of epoetin. However, the cross-sectional design of the present study does not offer proof of the causal effect of long-acting ESA on Hb at the initiation of dialysis. It is therefore essential to begin a longitudinal study to prove this potential beneficial effect of ameliorating anemia in CKD patients.

Declarations

Acknowledgements

The authors gratefully acknowledge Hiroyuki Sekihara, Moriaki Osaka, Hiroyuki Miyakawa, Hiromi Okamoto, Kazuhiko Kitano, and Ryoji Kijima for the management of the J-START database.

Financial support

None.

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors’ Affiliations

(1)
Division of Nephrology, Toho University Ohashi Medical Center
(2)
Division of Nephrology and Hypertension, The Jikei University Katsushika Medical Center
(3)
Department of Nephrology, Musashino Red Cross Hospital
(4)
Dialysis Center, Kawakita General Hospital
(5)
Kidney Center, Nagoya Daini Red Cross Hospital
(6)
Division of Nephrology, Department of Internal Medicine, Wakayama Medical University
(7)
Department of Nephrology, Division of Internal Medicine, St. Luke’s International Hospital
(8)
Division of Nephrology, Department of Internal Medicine, Showa University Fujigaoka Hospital
(9)
Department of Clinical Engineering, Social Insurance Chuo General Hospital
(10)
Department of Nephrology, Rinku General Hospital

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