Is decreased treatment time in hemodialysis patients harmful if solute clearance is maintained?

An association between decreased duration of hemodialysis and increased morbidity and mortality in patients has been suggested. Whether this is due only to decreased solute clearance is unclear. In this prospective randomised study the effect of reducing treatment time whilst maintaining constant solute clearance was examined in fourteen patients. The study lasted for a period of 36 weeks (3x12 week study periods) and used a crossover design. The patients dialysis prescription (KW) was not changed on entering the study and was maintained during short (150 minutes) and long dialysis (240 minutes) by varying blood flow, dialysate flow and dialyzer surface area. The delivered KW was kinetically assessed. Fractional urea clearance was also measured during each treatment period by measurement of urea concentration in spent dialysate and total body water using 3H2O. At the end of each treatment period a full biochemical and hematological profile, nutritional intake and status, 24 h ambulatory blood pressure, nerve conduction studies, and quality of life questionnaire were performed. Within patients the delivered single pool KW was uniform throughout the 3 treatment periods and fractional urea clearance did not vary. However, Kt/W assessed using equilibrated models (Daugardis and Smye) was significantly lower in the short dialysis period. No differences between short and long dialysis sessions were noted in any of the measured variables. Thus, over a 36 week period there is no evidence to suggest that hemodialysis patients are adversely affected by decreased duration of treatment provided that solute clearance is maintained.