Abstract
Purpose
Many dialysis centres have no formal program for assessing and adjusting post-haemodialysis (HD) target weight. Apart from clinical assessment, there are bioimpedance devices and natriuretic peptides that could potentially aid clinical management. We wished to determine whether pre- or post-HD bioimpedance assessment of extracellular water (ECW) or N terminal probrain natriuretic peptide (NT-proBNP) affected patient outcomes.
Methods
Multi-frequency bioimpedance assessments (MFBIA) were made before and after the midweek dialysis session, along with a post-dialysis NT-proBNP measurement.
Results
Data from 362 patients, median age of 63 (50–76) years, 59.7% male, 41.2% Caucasoid, with a median dialysis vintage of 31.4 (13.5–61.7) months were available for review. During a median follow-up of 49.6 (21.9–50.2) months there were 110 (30.4%) deaths. Patients who died had significantly increased ECW, as % over-hydrated both pre-HD 6.6 (5.8–7.6)% vs. survivors 5.1 (4–6.6)%, and post-HD 5.1 (4–6.6)% vs. 0.5 (-1-2.2.0, p<0.001, respectively. They also had higher NT-proBNP 325 (122–791) vs. 102 (48–342) pmol/l, p = 0.002. Using an adjusted Cox model, pre-HD ECW overhydration remained an independent factor associated with mortality (overhydration %: hazard ratio 1.15, 95% limits 1.03–1.28, p = 0.013), with a receiver operator curve (ROC) value of 0.7.
Conclusions
ECW excess is associated with increased mortality for HD patients, with ECW excess pre-dialysis being the strongest association, although these patients also had increased ECW post dialysis. Future trials are required to determine whether achieving euvolaemia as determined by bioimpedance improves patient survival.
Keywords
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