Middle-Molecular-Weight Toxins Removal of High-Dose Online Hemodiafiltration Compared with Expanded Hemodialysis: Evidence from a Mexican Cohort

Background: Middle-molecular weight toxins (MMWT) are involved in increased cardiovascular morbidity and in a high risk of mortality. We aimed to compare MMWT serum levels of patients after three months of treatment with online hemodiafiltration (OLHDF) versus expanded hemodialysis (HDx). Methods: A prospective longitudinal study was conducted. Thirty patients with more than 3 months on OLHDF were included. Sixteen patients were switched to HDx. Therefore, 14 patients were included in OLHDF group and 16 patients in HDx. B2 microglobulin (B2M), p-cresol and indoxyl sulfate were measured in serum at baseline and after three months of the two therapy modalities by commercial ELISA kits according to the manufacturer’s instructions. Either the Mann Whitney U test or the Student’s t test was used to assess differences between groups. Results: At baseline, clinical characteristics were similar between groups. Session time [OL-HDF (204 min (204, 206) HDx ( 203 min (201, 204)] and KT/V [OL-HDF 1.41 (1.32, 1.89) VS HDx 1.31 (1.06, 1.44)] were similar in both groups, the OLHDF group had an adequate convective volume (23.8 ± 2.1)After 3 months in OLHDF, medians of B2M (0.77 mg/L to 0.90 mg/L, p=0.057)], indoxyl sulfate levels (0.73 to 0.31, p=0.129), and p-cresol (4.2 pg/mL to 5.3 pg/mL, p=0.804) did not change significantly. Likewise, after 3 months of HDx, there were not significant changes in MMWT levels, B2M (0.75 mg/L to 0.84 mg/L, p=0.134), indoxyl sulfate (0.66 pg/mL to 0.52 pg/mL, p=0.222) and p cresol (11.7 pg/mL to 3.1 pg/mL, p=0.341) (Table 1). We found a significantly higher water consumption in the OLHDF group [118107 ml (115549,120972) vs 95337 (91592, 97883) p<0.001)] Conclusion: The analysis of the outcomes in these patients suggests that both OLHDF and HDx maintain stable levels of MMWT and that the switch from OLHDF to HDx does not represent a significant increase in these toxins.