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Lim Y, Yang G, Cho S, Kim SR, Lee Y-J: Association between Ultrafiltration Rate and Clinical Outcome Is Modified by Muscle Mass in Hemodialysis Patients. Nephron DOI 10.1159/000509350
Observational data have strongly implicated excessive ultrafiltration rates (UFR) as a possible contributor to adverse outcome in hemodialysis treatment of kidney failure. Many variables can affect this association, including “frailty” or abnormalities of body composition of the patients undergoing this modality of treatment.
Lim and coworkers examined the impact of reduced lean body mass (a measure of sarcopenia) assessed by body composition analysis in an observational study of 167 patients on maintenance hemodialysis. The median UFR was 11.4 mL/h/kg. During 284 person years of follow-up, death or first cardiovascular event (the primary outcome metric) occurred in 26% of the subjects and this outcome was predicted by a higher UFR but the hazard ratio for the primary event was quite low (HR 1.044; 95% CI 1.006–1.083). Each 1 mL/h/kg increase in UFR was associated with a 4% greater risk of the primary end point. Residual kidney function was not assessed. Low lean body mass (<12.5 kg/m2; sarcopenia) was identified as a possible marker of the adverse outcomes associated with high UFR.
As an observational study, these findings are hypothesis generating and not proof of concept. They do seem plausible and it would have been of interest to have quantitative information on the relationships of low lean body mass to indices of “frailty.” Only one body composition measurement was made in this cohort, so we do not know if increases in muscle mass attenuated the adverse effects of excessive UFR. Sarcopenia is well recognized to contribute to mortality risk. Taken together with available information on muscle mass and mortality risk, these studies point to the possible utility of assessment of muscle mass by body composition analysis in guiding the application of UFR in patients on hemodialysis. Whether attempt to improve sarcopenia (exercise training, nutritional modification, anabolic agents) will reduce the risks associated with high UFR remain as questions to be better understood.
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