HDCN Article Review/Hyperlink

Yang CS, Chen SW, Chiang CH, Wang M, Peng SJ, Kan YT

Effect of increasing dialysis dose on serum albumin and mortality in hemodialysis

Am J Kidney Dis (Mar) 27:380-386 1996

During a 6-year period the authors noted that Kt/V increased in their hemodialyzed patients from 1.3 in 1987 to 1.5 in 1990 to 1.7/dialysis in 1993. During the same period, mortality declined from 16.1 to 13.2 to 8.0 %/year and serum albumin concentrations increased from 3.8 to 4.0 to 4.3 g/dl. Since both low albumin concentrations and low Kt/V values are associated with increased mortality, the authors suggested that the improvement they observed in both albumin and mortality were caused by the increase in Kt/V.

Their study was observational, so cause-and-effect cannot be discerned and their study cannot be used as a basis for treatment. However, the data are important because they serves as a stimulus for more definitive interventional studies to determine the beneficial effect, if any, from further increases in Kt/V. Such a study is currently under way in the United States: the NIH-sponsored multi centered HEMO study. A previous NIH-sponsored interventional study in the late 1979's (NCDS) failed to show improvement in albumin or morbidity as Kt/V increased above 1.0/dialysis thrice weekly. Several more recent observational studies have suggested continued improvement in outcome as Kt/V is increased above 1.2/dialysis but others have not.

The authors of this report acknowledge that during the period of observation several other changes occurred in their dialysis center such as the introduction of EPO, reduction in number of transfusions, control of hepatitis, elimination of acetate and cellulose-based dialyzers, volume control of ultrafiltration, and improved water treatment, that could have contributed to the improvements in albumin and mortality. The absence of contemporary controls leaves open the possibility of an unidentified factor that may have influenced either the mix of patients admitted to the dialysis center or their risk of death. For example, patients dialyzed in more recent years may have been started sooner, thereby shortening their exposure to uremic toxins and preserving native kidney clearance. The increase in Kt/V itself could have resulted from acceptance of healthier patients who were able to tolerate more prolonged dialysis with higher blood flows. The authors acknowledge that "due to patient noncompliance," increasing the dose of dialysis (Kt/V) "was difficult before that time (1988)."

Comment: Because of the many alternative interpretations of their data, a statement made in the abstract that "increasing the dose of dialysis improves serum albumin levels" is too strong. The concept, however, is intriguing and deserves further study. (Thomas A. Depner, M.D., University of California Davis)