Do We Need to Abandon High Ultrafiltration Rates in America?

By Peter Laird, MD

Dialysis practices around the world differ significantly from the practice patterns observed in America and many have long believed this is in part the explanation for our higher dialysis mortality.

I recently spoke with a manager of a dialysis unit and his experience with horrified Japanese patients who couldn't believe the blood flow rates used in America compared to Japan. Japan, Europe, Australia and New Zealand have long recognized the survival benefits of longer, slower and gentler dialysis compared to our American style violent sessions.

A recent paper looked at the ultrafiltration rates as a marker of survival. In this retrospective analysis of nearly 2000 patients, the authors categorized the patients into three groups: Ultrafiltration rates 10ml/h/kg, 10-13ml/h/kg, and those over 13ml/h/kg.  The results are striking:

Rapid fluid removal during dialysis is associated with cardiovascular morbidity and mortality

Compared to ultrafiltration rates in the lowest group, rates in the highest were significantly associated with increased all-cause and cardiovascular-related mortality with adjusted hazard ratios of 1.59 and 1.71, respectively. Overall, ultrafiltration rates between 10–13 ml/h/kg were not associated with all-cause or cardiovascular mortality; however, they were significantly associated among participants with congestive heart failure. Cubic spline interpolation suggested that the risk of all-cause and cardiovascular mortality began to increase at ultrafiltration rates over 10 ml/h/kg regardless of the status of congestive heart failure. Hence, higher ultrafiltration rates in hemodialysis patients are associated with a greater risk of all-cause and cardiovascular death.

Many authors have recently noted similar results, but this study, albeit retrospective, carries significant weight due to the numbers of patients analyzed.  The high American dialysis mortality must be viewed in terms of our different dialysis practices first before corrective steps are implemented effectively. Abandoning sodium modeling will likely lead directly to lowered inter-dialytic weight gains that prompt the high ultrafiltration rates.  It is time for American nephrologists to critically evaluate our practices and eliminate those that are associated with higher mortality, and embrace those practices that lower mortality.