The predictive parameters of erythropoietin hyporesponsiveness in patients on continuous ambulatory peritoneal dialysis.
BACKGROUND
The present study was aimed at investigating the predictive parameters of erythropoietin (epoetin) hyporesponsiveness in patients on continuous ambulatory peritoneal dialysis (CAPD).


METHODS
We studied 40 patients with end-stage renal disease who had been receiving CAPD for at least 6 months and epoetin therapy for at least more than 2 months. Pearson's simple correlation and multiple stepwise linear regression analysis was used to discover what parameter can predict epoetin resistance. We expressed epoetin resistance index (ERI) as weekly epoetin dose/hematocrit/body weight'. The dose of epoetin is titrated by about 25% every 2 to 4 weeks to maintain a target hematocrit level between 33% and 36%.


RESULTS
We analyzed the relationship between ERI and other predictive parameters by Pearson's correlation. These results showed ERI has a statistically significant correlation with transferrin saturation (TS) (r = -0.327, p = 0.042), total weekly Kt/Vurea (r = -0.423, p = 0.018), serum albumin level (r = -0.458, p = 0.003), normalized protein catabolic rate (nPCR) (r = -0.479, p = 0.006), normalized protein equivalent of total nitrogen appearance (nPNA) (r = -0.488, p = 0.005) and serum C-reactive protein (CRP) (r = 0.332, p = 0.036). Regression analysis was performed using stepwise linear regression for multiple variables to discover the most independent variable which is correlated with ERI. ERI was entered as a dependent variable, whereas the other parameters (age, duration of peritoneal dialysis, serum albumin level, CRP, serum ferritin, total weekly Kt/Vurea, nPCR, nPNA, serum iPTH, serum aluminium, TS) were entered as independent variables. This analysis showed CRP is the most significant variable and, if CRP is excluded, nPNA is the significant variable. CRP has a statistically significant correlation with serum albumin level (r = -0.418, p = 0.007) and total weekly Kt/Vurea (r = -0.366, p = 0.043). High CRP group has more increased level of ERI (p < 0.05), age (p < 0.05) and serum creatinine level (p < 0.05) than normal control, but more decreased level of serum albumin (p < 0.01) and serum iron levels (p < 0.05).


CONCLUSIONS
These results indicate that CRP is the most important predictor of epoetin hyporesponsiveness.
Kim
J K
JK
Department of Internal Medicine, Chonnam National University Medical School, Hakdong 8, Dongku, Gwangju 501-757.
Park
B S
BS
Park
M J
MJ
Choi
W
W
Ma
S K
SK
Nah
M Y
MY
Yeum
C H
CH
Jung
K
K
Lee
S C
SC
Kim
S W
SW
Kim
N H
NH
Kang
Y J
YJ
Choi
K C
KC
D000328:Adult; D000740:Anemia / Q000188:drug therapy* / Q000209:etiology / Q000517:prevention & control; D001774:Blood Chemical Analysis; D002097:C-Reactive Protein / Q000032:analysis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004351:Drug Resistance; D004921:Erythropoietin / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000628:therapy*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010531:Peritoneal Dialysis, Continuous Ambulatory / Q000009:adverse effects* / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012044:Regression Analysis; D016896:Treatment Outcome
D004921:Erythropoietin; D002097:C-Reactive Protein