Background: Hemodiafiltration (HDF) is effective in delaying the surgical need for carpal tunnel syndrome in chronic hemodialysis patients, however, predialysis β₂-microglobulin levels were not reduced in most short-term studies. The aim of this study was to assess the effect of long-term and differing frequencies of on-line HDF on serum β₂-microglobulin levels in comparison to high-flux hemodialysis (HD). Methods: One hundred and twelve patients in the Chang Gung Memorial Hospital Dialysis Unit were divided into three groups to receive different frequencies of on-line HDF alternating with high-flux HD. Group 1 was treated once with HDF and twice with high-flux HD per week (n = 21). Group 2 was treated twice with HDF and once with high-flux HD per week (n = 33). Group 3 was treated with HDF three times per week (n = 58). Analysis was performed to compare the serum β₂-microglobulin levels in these groups and to high-flux HD. Results: After receiving HDF for a mean of 7.9 months, group 3 patients had a reduced predialysis β₂-microglobulin level (22.2 ±5.3 vs. 34.8 ±6.3 mg/l, p < 0.001), postdialysis β₂-microglobulin level (6.3 ± 2.0 vs. 13.8 ± 6.8 mg/l, p < 0.001) and an increased β₂-microglobulin reduction rate (76.1 ± 5.6 vs. 61.1 ± 13.3%, p = 0.03) when compared to high-flux HD. A significant improvement in URR (p = 0.0004), Kt/V (p = 0.0002) and TAC urea levels (p = 0.006) but not nPCR (p = 0.122) was found after patients had been treated with on-line HDF. The β₂-microglobulin reduction rate was positively correlated with the overall volume of the replacement solution per session (p < 0.0001). Patients in group 3 had lower predialysis β₂-microglobulin levels than those in group 1 and group 2 (22.2 ± 5.3 vs. 25.2 ± 7.2 vs. 26.0 ± 4.2 mg/l, p = 0.02). Furthermore, an inverse correlation was found between the predialysis β₂-microglobulin level and the duration of HDF, if patients were treated for more than 12 months (p = 0.031). Conclusion: On-line HDF has an increased dialysis efficiency compared to high-flux dialysis. Long-term HDF further reduced predialysis β₂-microglobulin levels, thus, it may provide an improved modality for renal replacement therapy.

Background: Recent investigation has shown that on-line hemodiafiltration (HDF) can reduce the amount of recombinant human erythropoietin (rhEPO) deemed necessary to reach the target hematocrit. The aim of this study was to analyze the potential effect of on-line HDF on rhEPO resistance in relation to iron utilization and anemia-related parameters, when compared to conventional hemodialysis (HD). Methods: Ninety-two chronic uremic patients were treated with conventional HD and then shifted to on-line HDF. Measurements of various erythropoiesis-related parameters were collected during HD and on-line HDF periods for statistical analysis for erythropoietin resistance. Results: Patients treated with on-line HDF switching from conventional HD significantly contributed to the reduction of EPO dose to reach a higher mean hematocrit level (31.8 ± 4.4% vs. 29.5 ± 3.9%, p < 0.001) and a reduction of the serum ferritin level (322.5 ± 268.4 vs. 544.9 ± 642.4, p < 0.001). The median EPO/Hct ratio was greater in the HD period (504.6 ± 310.1) than in the on-line HDF period (307.6 ± 334.4) (p < 0.001). These results indicated a reduced EPO resistance and improved iron utilization by on-line HDF. By multiple regression analysis, the significant predictors of EPO resistance are ferritin, transferrin, albumin, and TACurea (Time average concentration of urea) in HD treatment. In on-line HDF modality, in addition to ferritin and albumin, the duration of on-line HDF is a negative predictor in EPO resistance. Conclusion: When on-line HDF is recommended to chronic dialysis patients, long-term use of this technique provides an efficient means of achieving the goal of an elevated hemoglobulin by reducing EPO resistance, improved iron utilization and may further improve the quality of life.

On-line HDF offers a better cardiovascular stability and clinical improvement. Thrice weekly on-line HDF offers a significant benefit when compared with lower frequencies of HDF per week and high-flux HD.

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