Frequent Nocturnal Dialysis Offers Cardiac and Other Benefits

CALGARY, Alberta, Sept. 18 -- Nocturnal dialysis at home six times a week markedly reduced left ventricular hypertrophy in patients with end-stage renal disease compared with conventional treatment, according to a preliminary study.

Over six months, a decrease in left ventricular mass was accompanied by lower blood pressure and reduced need for blood pressure medications, lower parathyroid hormone and serum phosphate levels, and improvement in some health-related quality-of-life measures, Bruce F. Culleton, M.D., and colleagues at the University of Calgary reported in the Sept. 19 issue of the Journal of the American Medical Association.

Despite advances in dialysis and medical therapies, patients with end-stage renal disease have annual mortality rates exceeding 15%, with heart failure or sudden death responsible for the majority of deaths, Dr. Culleton, now with Baxter Healthcare in Deerfield, Ill., wrote.

Recent case-control and cohort studies have suggested that nocturnal dialysis might improve clinical outcomes health-related quality of life, the researchers said.

To investigate, they conducted a two-group, parallel, randomized controlled trial for six months at two Canadian university centers from August 2004 through December 2006.

A total of 52 patients were randomly assigned in a 1:1 ratio to receive nocturnal hemodialysis five to six times a week for a minimum of six hours a night or conventional hemodialysis three times a week.

In 44 patients who'd had baseline magnetic resonance imaging, left ventricular mass decreased a mean 13.8 g in those given nocturnal dialysis, compared with an increase of 1.5 g in those receiving conventional dialysis, for a difference of 15 .3 g (95% CI, 1.0-29.6 g, P=.04), the researchers reported.

This change was accompanied by improvements in systolic blood pressure (P=0.01 after adjustment) and mineral metabolism.

Specific improvements included a reduction in or discontinuation of antihypertensive medications for 16 of 26 patients in the nocturnal dialysis group. Only three of 25 patients in the conventional dialysis group achieved that mark (P

Study limitations, they wrote, included its small size and short duration of follow-up. It was also underpowered to detect differences in major cardiovascular events or survival.

"We believe the ultimate proof of the clinical value of nocturnal dialysis requires large-scale multicenter randomized trials with hard clinical endpoints," they said.

It is unlikely, they added, that future studies will be powered to detect differences in clinical outcomes such as mortality. As an example, they pointed out that a power analysis performed for a similar study showed that enrollment of more than 5,000 participants would be needed to achieve 90% power to detect a 30% reduction in mortality.

However, cost analyses are planned, and if nocturnal dialysis has a favorable cost-benefit profile compared with other dialysis therapies, "then consideration should be given to expansion of nocturnal dialysis centers, specifically for patients who wish to trade a more demanding therapy for less cardiovascular risk and a potential of improved quality of life," Dr. Culleton and colleagues said.

In an accompanying editorial, Alan S. Kliger, M.D., of Yale noted that the Canadian study is important for nephrology, clearly demonstrating reduced left ventricular hypertrophy with nocturnal hemodialysis.

It would be interesting, he said, to see the effect of nocturnal dialysis on cardiac structure and function beyond the six-month period of the study.

Dr. Kliger noted that the dialysis machines used for the nocturnal patients were similar to those used elsewhere. However, in the U.S. many home dialysis programs use different machines that are small, easier to use at home, and are designed to deliver longer, slower-flow dialysis. Thus the current study results may not be transferable.

Nevertheless, Dr. Kliger wrote, while further studies may provide additional information, Dr. Culleton's study suggests that nocturnal dialysis may help improve the high morbidity and mortality of North American dialysis patients.

Dr. Kliger is chair of the steering committee of the Frequent Hemodialysis Network, a randomized controlled trial of nocturnal and daily hemodialysis in progress, sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases and the Centers for Medicare & Medicaid Service.