Epoetin requirement does not depend on dialysis dose when Kt/N > 1.33 in patients on regular dialysis treatment with cellulosic membranes and adequate iron stores.

BACKGROUND: An inverse correlation between Kt/V and epoetin requirement has recently been demonstrated in stable hemodialysis (HD) patients with adequate iron stores, dialyzed with cellulosic membranes. However, there is no evidence as to whether or not this effect continues for Kt/V even in the adequate or higher range.
METHODS: We investigated the relationship between Kt/V and the weekly epoetin dose in 85 stable HD patients (age 63 +/- 16 years) treated with bicarbonate HD and unsubstituted cellulose membranes for 6-338 months (median: 70 months). INCLUSION CRITERIA: HD for at least 6 months, subcutaneous rHuEPO for at least 4 months, transferrin saturation (TSAT) > or = 20%, serum ferritin > or = 100 ng/mL, hemoglobin (Hb) level targeted to approximately equal to 12 g/dL for at least 3 months. EXCLUSION CRITERIA: HBsAg and HIV positivity; need for blood transfusions or evidence of blood loss in the 3 months before the study, acute and chronic infections. To evaluate the effect of dialysis adequacy on the epoetin requirement, we also performed the same analysis after dividing of the patients according to Kt/V. Hematocrit (Hct) and Hb levels were evaluated weekly for 3 weeks; TSAT, serum ferritin, Kt/V, PCRn, serum albumin (sAlb), and weekly epoetin dose were evaluated at the end of observation. No change in dialysis or therapy prescription was made during the study.
RESULTS: The results for all the patients were: Hct 36 +/- 2 %, Hb 12 +/- 0.7 g/dL, TSAT 28 +/- 7%, serum ferritin 234 +/- 171 ng/mL, sAlb 4.2 +/- 0.4 g/dL, Kt/V 1.33 +/- 0.17, PCRn 1.15 +/- 0.28 g/Kg/day, weekly epoetin dose 117 +/- 74 U/Kg. There was no correlation between Hb and Kt/V, whereas there was an inverse correlation between the reciprocal of the weekly epoetin dose and Kt/V (r = -0.448, p = 0.0001). Further regression line analysis showed a break-point for Kt/V at the level of 1.33. In the 52 patients with Kt/V < 1.33, the correlation was confirmed between epoetin and Kt/V (r = - 0.563, p = 0.0001), while in the 33 patients with Kt/V > or = 1.33, there was no correlation between epoetin dose and Kt/V (r = 0.021, p = NS). In these patients, multiple regression analysis, with the weekly epoetin dose as a dependent variable, confirmed Kt/V as a non-significant factor.
CONCLUSIONS: In iron-replete HD patients on cellulosic membranes and stabilized epoetin therapy, inadequate dialysis was associated with higher epoetin requirement, but for Kt/V values > or = 1.33, there was no further effect on epoetin responsiveness.