Predilution online hemodiafiltration is associated with improved survival compared with hemodialysis

On-line hemodiafiltration is an increasingly common alternative to chronic hemodialysis in some countries, based on the results of randomized controlled trials of post-dilution on-line hemodiafiltration. There are now more than 60,000 patients treated with on-line hemodialfiltration in Japan, over 95% of whom use predilution on-line hemodiafiltration; however, large-scale data on clinical outcomes with this modality are lacking. We created a propensity-matched cohort of 5,000 pairs of patients treated with conventional hemodialysis or predilution on-line hemodiafiltration, using the Japanese Society for Dialysis Therapy Renal Data Registry database from December 31, 2012 to December 31, 2013. One-year all-cause and cardiovascular mortality were compared between the groups. Predilution on-line hemodiafiltration was associated with improved overall survival compared to hemodialysis (hazard ratio for all cause-mortality 0.83, 95% confidence interval 0.705–0.986), with a trend towards improved cardiovascular survival. Among patients treated with predilution on-line hemodiafiltration, those treated with high substitution volumes (≥40.0 L per session) had improved all-cause and cardiovascular survival compared to those treated with low substitution volumes (<40.0 L per session) or those on hemodialysis. The optimal substitution volume associated with improved overall survival was estimated to be 50.5 L [95% confidence interval 39.0–63.5 L]. This observational study suggests that predilution on-line hemodiafiltration, especially with high substitution volumes, may improve all-cause and cardiovascular survival, but randomized controlled trials are needed.