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Abstract: SA-OR50

Association Between Ultrafiltration Rates and All-Cause Death in Patients Undergoing Extended-Hours Hemodialysis Using Time-Fixed and Time-Dependent Models: The LIBERTY Cohort

Session Information

Category: Dialysis

  • 801 Dialysis: Hemodialysis and Frequent Dialysis


  • Imaizumi, Takahiro, Nagoya Daigaku, Nagoya, Aichi, Japan
  • Okazaki, Masaki, University of California Irvine School of Medicine, Irvine, California, United States
  • Maruyama, Shoichi, Nagoya Daigaku, Nagoya, Aichi, Japan

Overhydration or excessive fluid removal during dialysis sessions is a risk for congestive heart failure (CHF) and death for dialysis patients, as evidence shows that the ultrafiltration rate (UFR) was associated with CHF and all-cause death. Studies have shown that extended-hours hemodialysis (EHD, >18 hr/w) improves various dialysis-related parameters such as hemoglobin, phosphate, and left ventricular hypertrophy, as well as survival. Although EHD may prevent congestion, the appropriate range of UFR in patients undergoing EHD is unknown.


Using data from 636 patients undergoing EHD in the LIBeralized diet Extende-houRs hemodialysis TherapY (LIBERTY) cohort, we examined the association between UFR and all-cause death in time-fixed or time-dependent multivariable Cox models adjusted for dialysis conditions and laboratory data. UFR was calculated by fluid removal (mL) per hour divided by dry weight (kg) and averaged in a week (mL/h/kg). UFR and covariates at baseline (within 6 months from EHD initiation) were used in the time-fixed model, while, the mean values of UFR and covariates every 3 months in a time-updated manner were used in the time-dependent model.


The mean age was 62 years and male participants comprised 65%. Median UFR was 7.0 mL/kg/h. The median time since starting dialysis was 1.8 [IQR, 0.1–5.6] years. During a median of 6.4 [IQR, 3.4–10.3] years, 230 patients died. Overall survival at 5 years from the baseline was 79% (95% CI, 76–83%). Baseline UFR was not associated with all-cause death (Log-rank test P=0.091, Figure A). In the multivariable-adjusted models, baseline UFR was not associated with the outcome, while low or high time-updated UFR was associated with the outcome (Figures B and C).


UFR at the start of EHD was not associated with all-cause mortality, while time-updated UFR <7 mL/kg/h, which may represent reduced dietary intake, was associated with short-term prognosis.


  • Government Support – Non-U.S.