Continuous vs. intermittent dialysis produced same results, analysis shows
TUESDAY, Feb. 19 (HealthDay News) -- Studies show no particular advantage to any single treatment for acute renal failure, the sudden collapse of kidney function that carries with it a high risk of death, Canadian researchers report.
An analysis of 38 trials found no difference in the death rates, which are usually higher than 30 percent, for one method or another, according to a report in the Feb. 20 issue of the Journal of the American Medical Association.
Methods used in the various trials were continuous renal replacement therapy (CRRT), in which the person whose kidneys have failed gets continuous dialysis, a machine treatment that removes impurities from the blood, and intermittent hemodialysis, in which the purifying treatment is not continuous.
"There doesn't seem to be any difference in any measurable outcome that has been evaluated in trials," said study author Dr. Neesh Pannu, an assistant professor of pathology and critical care medicine at the University of Alberta, in Edmonton. "We were not able to identify any subgroup that might have any benefit from one method over the other."
But that can't be said with certainty because most of the trials were small, Pannu added. "There has been a relatively small number of patients, so it is hard to look at any subgroups," she said."This is a very difficult area, and it's hard to study it," said Dr. Richard Swartz, a professor of internal medicine at the University of Michigan and leader of one of the studies included in the analysis. "Acute kidney failure usually is a consequence of bad things happening to people. You have to look at what brought you to kidney failure -- heart disease, lung disease, systemic infections, all of those things contribute to mortality."
"Unless you can account for these comorbidities, you can't account for what a treatment is actually contributing," he said. "The more complex it gets, the harder it is to randomize patients into a study. Depending on what the patients suffer from, the outcomes are quite variable."
The incidence of acute kidney failure appears to be increasing, the report said, although exact numbers are lacking. Recent studies have indicated that chronic kidney disease is on the rise in the United States, with the increased linked to obesity, diabetes and high blood pressure. One report last year said the prevalence of chronic kidney disease had risen in a decade from 10 percent to 13 percent of the U.S. population.
Someone with chronic kidney disease can be kept alive for years, by dialysis and perhaps a kidney transplant. The outlook is much grimmer in many cases of acute kidney failure because of the medical problems that led the kidneys to suddenly stop working, Swartz said.
"We looked at all the patients we treated and tried to account for as many of these kinds of factors for which we could get data," he said. "We found it extremely difficult, and most of my colleagues would tell you the same thing."
There has been a belief that continuous dialysis might be better overall, especially for sicker patients, said Dr. Mitchell H. Rosner, an assistant professor of internal medicine at the University of Virginia. "It keeps blood pressure low and is slower and more gentle," he said. "But the data are showing more and more that, despite the theoretical advantages, when CRRT is put to the test, it doesn't perform as expected."
However, CRRT might still be preferable in some cases, Rosner said. "It sometimes is just not practicable to give intermittent dialysis," he said. "It requires more nursing and more effort. Continuous dialysis is simpler to do."
The decision can also be influenced by the capabilities of individual centers, Swartz added. "It depends on the expertise in doing a particular kind of treatment," he said. "That varies from center to center."
Causes and treatment of kidney failure are described by the U.S. Library of Medicine.
SOURCES: Richard Swartz, M.D., professor, internal medicine, University of Michigan, Ann Arbor; Mitchell H. Rosner, assistant professor, internal medicine, University of Virginia, Charlottesville; Neesh Pannu, M.D., assistant professor, pathology and critical care medicine, University of Alberta, Edmonton; Feb. 20, 2008, Journal of the American Medical Association
All rights reserved