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Dialysis three times a week may not be enough


A major study challenges the way diabetics and others with failing kidneys have been treated for half a century, finding that three-times-a-week dialysis to cleanse the blood of toxins may not be enough.

Deaths, heart attacks and hospitalizations were much higher on the day after the two-day interval between treatments each week than at other times, according to the results published this week in the New England Journal of Medicine.

Kidneys rid the body of waste and fluids. Most people with failing kidneys stay alive by getting their blood purified by a machine three days a week at dialysis clinics – usually on Mondays, Wednesdays and Fridays or on Tuesdays, Thursdays and Saturdays. In both cases, there's a two-day break between the last session of the week and the next one.

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The three-day dialysis schedule has been around since the mid-1960s and gives patients a weekend break from the gruelling hours of being hooked up to a machine.

However, doctors have suspected that the two-day hiatus between treatments was risky, and smaller studies have found more heart-related deaths on the day after the gap.

"All the fluids and toxins are built up to the highest extent on Monday morning right before dialysis," said Anthony Bleyer of Wake Forest Baptist Medical Center in North Carolina, who has done similar studies.

The latest research, funded by the U.S. National Institutes of Health, is the largest yet. It was done by Robert Foley of the University of Minnesota and colleagues. All reported receiving fees from dialysis clinics and suppliers.

The team analyzed medical records of 32,000 people who had in-centre dialysis three times a week from 2005 through 2008. The average age was 62 and a quarter had been on dialysis for a year or less. After about two years of follow-up, 41 per cent had died, including 17 per cent from heart-related causes.

Monday was the riskiest day for people on a Monday-Wednesday-Friday schedule. For those on a Tuesday-Thursday-Saturday schedule, the riskiest day was Tuesday.

Researchers found a 22-per-cent higher risk of death on the day after a long break compared with other days of the week. Put another way: For every 100 people on dialysis for a year, 22 would die on the day after the long interval versus 18 on other days.

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Hospital admissions for stroke and heart-related problems more than doubled on the day after a long break than on other days – 44 versus 20 for every 100 people treated.

Fixing this problem, however, could be daunting for patients, and busy dialysis centres would require a rethinking of how dialysis is currently delivered.

There has been recent interest in more frequent dialysis after studies hinted that it made people feel healthier.

For instance, a growing number of patients in both the United States and Canada have been doing dialysis at home, allowing them to cleanse their blood more often.

With so-called nocturnal dialysis, they are hooked up to a machine six nights a week, for about seven hours a stretch while they sleep.

In conventional dialysis, blood is pumped in and out of the body quickly, which can wreak havoc on blood pressure and the heart. In nocturnal dialysis, blood is pumped and cleansed more slowly, and research has shown it is far less damaging to the heart. Some studies have shown that patients on home dialysis had better heart function, lower blood pressure, a reduced need for medication and a better quality of life than those on in-hospital dialysis.

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However, this method of dialysis is not for everyone. It requires intense training and patients need a helper at home, experts point out.

The other option is a kidney transplant. But the supply of available organs falls far short of what's needed.

For those who must rely on hospital dialysis, Dr. Bleyer said people can take simple steps to reduce their risk by not drinking too much fluid between long dialysis breaks and eating a healthy diet.

The Associated Press with files from The Globe and Mail

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