Nutritional status after conversion from conventional to in-centre nocturnal hemodialysis

Recipients of conventional hemodialysis (CHD; 3-4 h/session, 3 times/week) experience volume expansion and nutritional impairment which may contribute to high mortality. Prolongation of sessions with in-centre nocturnal hemodialysis (INHD; 7-8 h/session, 3 times/week) may improve clinical outcomes by enhancement of ultrafiltration and uremic toxin removal.

In this prospective cohort study, 56 adult patients who were receiving maintenance CHD for at least 90 days were assigned to CHD (patients who remained in CHD) and INHD (patients who switched to INHD) groups. Both groups were followed for 1 year divided into four 13-week quarters; post-dialysis weight and interdialytic weight gain (IDWG) were captured in each quarter. Repeated measures analysis of variance was used to calculate group main effect, time main effect or time-group interaction effect.

Conversion to INHD was associated with a mean (95% confidence interval) change in IDWG of 0.5 (0.08, 1.2) kg as compared to -0.3 (-0.9, 0.1) kg in the CHD group (p < 0.01). In the INHD group, post-dialysis weight (% of baseline pre-dialysis weight) decreased after conversion, reaching a nadir during the first 3 months (0.7%) and subsequently it gradually increased and returned to its baseline at the end of follow-up. A similar temporal trend was seen for serum creatinine but not serum N-terminal pro-brain natriuretic peptide (NT-proBNP) which is a marker of extracellular volume. The changes in serum albumin, prealbumin and hs-CRP were not different between the two groups.

Conversion to INHD was associated with greater IDWG and relatively stable body mass. We speculate that this gain in weight reflects an increase in lean body mass following the change in dialysis modality, which can be concluded from the parallel increase in serum creatinine and the lack of increase in NT-proBNP.