Greater fluid overload and lower interdialytic weight gain are independently associated with mortality in a large international hemodialysis population

Abstract

BackgroundFluid overload and interdialytic weight gain (IDWG) are discrete components of the dynamic fluid balance in haemodialysis patients. We aimed to disentangle their relationship, and the prognostic importance of two clinically distinct, bioimpedance spectroscopy (BIS)-derived measures, pre-dialysis and post-dialysis fluid overload (FOpre and FOpost) versus IDWG.MethodsWe conducted a retrospective cohort study on 38 614 incident patients with one or more BIS measurement within 90 days of haemodialysis initiation (1 October 2010 through 28 February 2015). We used fractional polynomial regression to determine the association pattern between FOpre, FOpost and IDWG, and multivariate adjusted Cox models with FO and/or IDWG as longitudinal and time-varying predictors to determine all-cause mortality risk.ResultsIn analyses using 1-month averages, patients in quartiles 3 and 4 (Q3 and Q4) of FO had an incrementally higher adjusted mortality risk compared with reference Q2, and patients in Q1 of IDWG had higher adjusted mortality compared with Q2. The highest adjusted mortality risk was observed for patients in Q4 of FOpre combined with Q1 of IDWG [hazard ratio (HR) = 2.66 (95% confidence interval 2.21–3.20), compared with FOpre-Q2/IDWG-Q2 (reference)]. Using longitudinal means of FO and IDWG only slightly altered all HRs. IDWG associated positively with FOpre, but negatively with FOpost, suggesting a link with post-dialysis extracellular volume depletion.ConclusionsFOpre and FOpost were consistently positive risk factors for mortality. Low IDWG was associated with short-term mortality, suggesting perhaps an effect of protein-energy wasting. FOpost reflected the volume status without IDWG, which implies that this fluid marker is clinically most intuitive and may be best suited to guide volume management in haemodialysis patients.

Bioimpedance spectroscopy for fluid status assessment in patients with decompensated liver cirrhosis: Implications for peritoneal dialysis

“…Moreover, we did not observe any correlation between BCM-BIS derived FO and the treatment with diuretics, either before or after the abdominal paracentesis (p = 1.0 and p = 1.0, respectively), or between the use of diuretics and edema (p = 1.0). In the nephrological community, BCM-BIS revealed the interesting phenomenon that a large proportion of hemodialysis patients (approximately 25% of patients with end stage kidney failure on maintenance hemodialysis or PD [65][66][67][68] ) were fluid overloaded >15% ECV predialysis, despite the fact that these patients were under constant care of their nephrologist and dialysis care takers. Clinical experience shows that fluid overload is hard to detect 69 .…”

Body Fluids in End-Stage Renal Disease: Statics and Dynamics

“…On the other hand, high UFR, which is associated with adverse outcomes, is associated with steeper RBV curves, which are associated with better outcomes but also with a larger decline in S cv O 2 , which is again associated with worsened outcomes. In addition, high UF volumes are not always associated with the worst outcomes, which were actually observed in a group with both FO and low UF volumes [58]. Most likely, significant comorbidity may have hampered fluid removal in this group of patients and may also be a contributing factor to the paradoxical associations discussed above.…”

Systematic Fluid Assessment in Haemodialysis: Development and Validation of A Decision Aid

“…There is an association between IDWG and fluid overload, but conversely, unexpectedly low weight gain between dialysis sessions could indicate inferior nutritional intake in patients with severe fluid overload, which is independently associated with mortality (Hecking et al . ).…”

“…Still, many patients with fluid overload do not show obvious signs of oedema or breathing difficulties, while chest infections or anaemia can cause breathlessness to complicating their use as markers of fluid overload. There is an association between IDWG and fluid overload, but conversely, unexpectedly low weight gain between dialysis sessions could indicate inferior nutritional intake in patients with severe fluid overload, which is independently associated with mortality (Hecking et al , 2018.…”