Adverse Effects of Conventional Thrice-Weekly Hemodialysis: Is It Time to Avoid 3-Day Interdialytic Intervals?

Background: Maintenance hemodialysis is typically scheduled thrice weekly due to simple logistic reasons; thus, the vast majority of hemodialysis patients receive renal replacement therapy for two shorter 2-day intervals and a longer 3-day interval. As compared to the 2-day interval, we review the ill effects of the longer 3-day interdialytic interval in this report. Summary: Large-scale observational studies show that both cardiovascular-related hospital admissions and mortality occur more frequently on the day following the long interdialytic interval than on any other day of the week. Although the reasons for excess mortality are obscure, several pathophysiologic mechanisms may be involved, such as a greater magnitude of change during the long interdialytic interval in the following parameters: volume status, electrolyte and acid-base status, arterial wall and left ventricle mechanics. These data raise the need for re-examining the issue of timing and frequency of prescribed dialysis regimens in an attempt to improve patient outcomes. Although enhanced-frequency and/or extended-time dialysis schedules may mitigate the risks of the long interdialytic interval, the benefit of such dialytic modalities on survival is not yet proven. Key Message: This article summarizes currently available epidemiologic and pathophysiologic evidence on the adverse effects related to the long interdialytic interval of thrice-weekly hemodialysis and discusses the need to research further alternative dialysis practices that could mitigate these risks.