Should Dialysis Frequency Be Slightly Increased?

It’s customary for patients having renal dialysis for end-stage renal disease (ESRD) to receive dialysis three days a week – i.e. two one-day and one two-day intervals between sessions.  This ‘cadence’ has developed over many years, and is generally accepted as the best compromise between effectiveness, safety, and convenience.  But Minnesota kidney specialists have wondered if a two-day interval was detrimental to the patient, so they conducted a retrospective study of data from a nationally representative sample of US patients who received dialysis three times a week. Their findings are published in the New England Journal of Medicine.     

Just over 32,000 dialysis patients were followed for an average of 2.2 years. Rates of death and cardiovascular-related hospital admissions on the day after the two-day interval were compared with rates for other days.

The patients were aged 62, on average, and had been on dialysis for one year or less at their entry to the study.  All-cause mortality rates were highest on the day of dialysis after a two-day interval;  mortality was then about the same (lower) level for the other days of the week – 22.1 vs. 18.0 deaths per 100 person-years.  Deaths from cardiac causes, infection, cardiac arrest, and myocardial infarction (MI, or heart attack) were all significantly increased for the two-day compared with the one-day intervals.

Admission for any cardiovascular event was also highest on the dialysis day after a two-day interval. Heart attack, heart failure, stroke, and irregular heartbeat were all significantly more common after the two-day dialysis interval.  

Dialysis is expensive, and the logical consequence of this study might be to switch patients to one-day intervals throughout, which would entail an extra dialysis day every 2 weeks.  Maybe one needs to make a cost analysis of this step, compared with ‘no change’.  Even then, however, patients will probably elect to continue to have their weekends free, and take the slight but significant increased risk in stride.