Role of Residual Kidney Function and Convective Volume on Change in β2-Microglobulin Levels in Hemodiafiltration Patients

Abstract

Background and objectives: Removal of ␤ 2 -microglobulin (␤2M) can be increased by adding convective transport to hemodialysis (HD). The aim of this study was to investigate the change in ␤2M levels after 6-mo treatment with hemodiafiltration (HDF) and to evaluate the role of residual kidney function (RKF) and the amount of convective volume with this change.Design, setting, participants, & measurements: Predialysis serum ␤2M levels were evaluated in 230 patients with and 176 patients without RKF from the CONvective TRAnsport STudy (CONTRAST) at baseline and 6 mo after randomization for online HDF or low-flux HD. In HDF patients, potential determinants of change in ␤2M were analyzed using multivariable linear regression models.Results: Mean serum ␤2M levels decreased from 29.5 ؎ 0.8 (؎SEM) at baseline to 24.3 ؎ 0.6 mg/L after 6 mo in HDF patients and increased from 31.9 ؎ 0.9 to 34.4 ؎ 1.0 mg/L in HD patients, with the difference of change between treatment groups being statistically significant (regression coefficient ؊7.7 mg/L, 95% confidence interval ؊9.5 to ؊5.6, P < 0.001). This difference was more pronounced in patients without RKF as compared with patients with RKF. In HDF patients, ␤2M levels remained unchanged in patients with GFR >4.2 ml/min/1.73 m 2 . The ␤2M decrease was not related to convective volume. Conclusions: This study demonstrated effective lowering of ␤2M levels by HDF, especially in patients without RKF. The role of the amount of convective volume on ␤2M decrease appears limited, possibly because of resistance to ␤2M transfer between body compartments.

Effect of Online Hemodiafiltration on All-Cause Mortality and Cardiovascular Outcomes

“…In a previous analysis of the CONTRAST study, we showed that the effect of online hemodiafiltration on b-2-microglobulin levels was especially present in patients without residual kidney function. 7 However, neither residual kidney function, nor an analysis of other predefined subgroups, such as primary kidney disease, age, co-morbidity, and sex modified the effect of treatment in our study. Because the CONTRAST study was not powered to detect differences between low-flux hemodialysis and hemodiafiltration on outcome across subgroups, our "null" results in subgroup analyses do no exclude the presence of such a relation.…”

“…With modern online hemodiafiltration equipment, high convection and substitution volumes can be reached safely, 3 resulting in markedly enhanced removal of middle molecular mass substances. [4][5][6][7] Several nonrandomized observational studies suggested a survival benefit in patients who are treated with online hemodiafiltration. [8][9][10][11] However, small randomized studies failed to show a difference between online hemodiafiltration and standard hemodialysis (as summarized by van der Weerd et al 12 ).…”

Role of Residual Renal Function in Phosphate Control and Anemia Management in Chronic Hemodialysis Patients

“…Apart from phosphate and anemia control, our data showed a strong relation between RRF and ␤2M level, as previously reported (6,7,49), and suggested that even a GFR Ͻ1.65 ml/min contributes to ␤2M removal. Notably, we have recently shown that RRF appears to be more important for ␤2M removal than intensifying dialysis treatment with online hemodiafiltration (50). Not surprising, but of potential clinical interest, is the finding that intradialytic weight loss was much lower in patients with urinary output as compared with anuric patients.…”

Treatment frequency and mortality among incident hemodialysis patients in the United States comparing incremental with standard and more frequent dialysis

“…17,18,24 These benefits are thought to be mediated by continuous and efficient clearance of middle molecules and protein-bound solutes, better fluid management, more endogenous vitamin D and erythropoietin production, and less inflammation. [25][26][27][28] Decline and loss of RKF are associated with higher mortality, 18 and the frequency of HD may contribute to loss of RKF. In our study, we found that patients initiated on a frequent HD regimen ($4 times per week for at least 45 continuous days) had a higher mortality than patients initiated on an incremental or conventional regimen.…”