“Long Interdialytic Interval and Mortality Among Patients Receiving Hemodialysis”
Robert N. Foley et al, N Engl J Med 2011; 365:1099-1107

This article in the September 22nd edition of the New England Journal of Medicine stirs up further controversy over the traditional schedule of hemodialysis for patients with end-stage kidney failure.

For most patients who require it, maintenance dialysis tends to be performed three times a week – typically “Monday, Wednesday, and Friday”, or “Tuesday, Thursday, and Saturday”. This leaves most patients with two 1-day intervals between sessions, and one 2-day interval (either between Friday and Monday, or Saturday and Tuesday).


Some Background
Since the occurrence of cardiovascular complications is high in these patients, the group of researchers hypothesized that the risk of such problems would be heightened after the longer, 2-day interval between dialysis sessions.


What They Found
They studied 32,065 patients with end-stage renal disease who were receiving hemodialysis three times weekly from 2004-2007. They compared the rates of death and cardiovascular-related hospital admissions on the day after the 2-day interval. They found an increase in morbidity and mortality on the day after the long dialysis weekend. Events that were increased at this time included:

  • Mortality (all-cause mortality in general, as well as death due to infection, myocardial infarction, and other cardiac events in particular)
  • Hospital admissions (for problems such as stroke, congestive heart failure, abnormal heart rhythym, myocardial infarction)

So clearly a longer interval of 2 days between dialysis presents an increased risk for patients. What the study didn’t address, however, was whether what the patients were doing on that “day off” could have played a role in the events leading up to morbidity or mortality. Regardless, however, the long dialysis weekend still seems to spell trouble for patients.


What Does It All Mean?
Consequently, it seems that more dialysis is better – although this is not a new concept to healthcare professionals who deal with such patients on a daily basis. Despite being widely known that the end of the long dialysis weekend is a time of heightened risk to dialysis patients, relatively few studies have actually evaluated the association. It has gained more interest in recent years, however, allowing some clinical trials to demonstrate improved outcomes in patients as a result of daily dialysis sessions. 

Although the answer seems to lie in providing daily dialysis sessions, it probably isn’t as simple as it sounds. Inevitably, problems such as patient compliance, and the mechanics of providing daily dialysis will likely come into play. Additionally, as is the case with all-things-medical, no doubt the sheer business and financial implications of such daily treatment will continue to hinder the situation.



  1. Doesn’t dialysis take hours to complete? Someone would be tethered to a machine for half their life. Do people ever get depression over that quality of life?

    • Yes Jacqui, they do – most take around 4 hours. The time depends on many things though, including what’s happened to your body in between sessions. So I suspect their duration would decrease a little if frequency was increased. A small mercy!