Samir H. Almueilo

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http://dx.doi.org/10.5772/64591

#### **Abstract**

Online hemodiafiltration (OL-HDF) as a renal replacement therapy is gaining momentum due to the perceived added benefit from enhanced clearance of potential‐ ly harmful middle molecules. Favorable effect of OL-HDF on all-cause mortality and cardiovascular mortality and morbidity has been suggested by some clinical trials. Health-related quality of life (HRQOL) is an important component of hemodialysis patients' care. HRQOL is of interest to both health care providers and patients. Improved quality of life in hemodialysis patients has been associated with improved outcome in terms of reduced rate of hospitalization and mortality. Data on HRQOL in end-stage renal disease (ESRD) patients under OL-HDF is scarce and of marginal quality. In this review, we will try to summarize the available evidence on this subject.

**Keywords:** Quality of life, Health-related quality of life, Online hemodiafiltration, He‐ modiafiltration, End-stage renal disease

### **1. Introduction**

End-stage renal disease (ESRD) is characterized by significantly increase rate of mortality and morbidity. Survival of patients with end-stage renal disease is substantially decreased com‐ pared to counterparts without renal failure. It is estimated that 10–20 % of dialysis patients die annually [1]. Historically, in patients with ESRD, survival has been commonly utilized as a measure of outcome, as both health care providers and patients are most interested in prolong‐ ing life.

Quality of life (QOL) is curtailed in these patients not only due to the physical burden of the disease but also due to its effect on psychological, social interaction, rehabilitation, and employment component of patient life. Renal replacement therapy decreases morbidity related

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to uremia and improves many of the uremic symptoms such as anorexia, fatigue, and pruritus that have a negative impact on the quality of daily life.

Conventional hemodialysis (HD) is reasonably effective in removing small solutes by way of diffusion across membranes. However, middle molecules which are implicated in adverse outcome are poorly removed by such mechanism. Secondary analysis of the HD trial had suggested that survival may depend on clearance of such middle molecules [2]. Convective therapy is more effective in removing larger toxic middle molecules such as β2-microglobulin. High-volume online hemodiafiltration (OL-HDF) effectively achieves significant clearance of middle molecules. Such treatment has been shown to be beneficial in terms of lower risk of all-cause and cardiovascular mortality when compared to standard hemodialysis. Secondary analysis of initially negative clinical trials also demonstrated decreased mortality in recipients of high-volume OL-HDF [3–7].

Hemodiafiltration (HDF) combines diffusive and convective clearance of uremic solutes. It involves convection of large volume of fluid and infusing in the patient a replacement fluid that is ultrapure, sterile, and free of pyrogens. Utilization of online HDF where replacement fluid is prepared by further purifying dialysate fluid instead of manufacturer-provided solutions made it more practical and cost effective. It is believed that high-volume HDF by increasing clearance of middle molecules could potentially improve symptomatology, reduces morbidity, and may even improve survival [8]. These in turn could result in improved quality of life. Improved quality of life in hemodialysis patients has been associated with improved outcome. Analysis of data using the Kidney Disease Quality of Life Short Form (KDQOL-SFTM) obtained from 10,030 randomly selected hemodialysis patients from the USA, five European countries and Japan in the Dialysis Outcomes and Practice Patterns Study (DOPPS) demonstrated associations between HRQOL and the risk of death and hospitalization. Scores were determined for three components of HRQOL: (1) physical component summary (PCS), (2) mental component summary (MCS), and (3) kidney disease component summary (KDCS). Lower scores for the three major components of HRQOL were strongly associated with higher risk of death and hospitalization in hemodialysis patients, independent of a number of demographic and comorbid factors [9].

Information on quality of life in patients receiving renal replacement therapy in the form of OL-HDF is scarce and inconclusive. The studies often involve small sample size and uses different methods of quantifying HRQOL. In this report, we will attempt to address HRQOL in patients under OL-HDF treatment by way of defining HRQOL, describing the most common instruments used to evaluate HRQOL and presenting brief summaries of clinical studies that investigated HRQOL in individuals receiving convective therapy.
