If you need dialysis for advanced kidney disease, where you get it could make a big difference. A large study found that patients in certain large chain facilities are significantly more likely to die than those treated elsewhere. Mortality was also higher in for-profit than non-profit dialysis centers.

“The differences were not minor,” said Yi Zhang, Ph.D., lead study author. “We need to find out what caused them.”

Zhang is a senior research associate at Medical Technology and Practice Patterns Institute in Bethesda, Md. Her study appears online in the journal Health Services Research.

The researchers analyzed data involving 34,914 Medicare patients treated in 3,601 non-hospital dialysis centers in 2004. They compared statistics for each of five chains, and for non-chain for-profit and nonprofit facilities.

After adjusting for patient factors that might affect , such as age and concurrent diseases, the researchers found that the risk of death over an 18-month to 30-month period was 19 percent and 24 percent higher for patients of the two largest chains – both of which were for-profit – than for patients of a medium-size nonprofit chain.

Overall, patients were 13 percent more likely to die if they attended for-profit rather than non-profit facilities.

These findings are particularly meaningful in light of ongoing trends toward consolidation, the authors wrote: the two largest chains now treat nearly 60 percent of all dialysis patients.

The study “raises questions instead of giving definitive answers,” Zhang said. “Mortality rates among dialysis patients have improved, but are still unacceptably high. Finding a way to improve survival is an important public health issue."

Differences between facilities, including such staffing patterns as numbers of physicians and the ratio of registered nurses to technicians, “need to be examined in future studies,” she said.

The findings of this study “may be alarming for some patients who receive their care in for-profit chains, but it certainly doesn’t mean for-profits are bad or should close up shop,” said Brennan Spiegel, M.D., associate professor of medicine at West Los Angeles VA Medical Center. “Ultimately, consumers are cared for by individual people, not by an organization, and I know that many units in for-profit chains are doing great.”

The study’s “top-down” overview of groups of facilities points to the need to examine in detail patient, staff and management characteristics that might explain mortality differences between units in a single organization as well as between organizations, he said.

“We’re learning about these big communities from the view at 30,000 feet. Now we have to go down to ground level, walk around the blocks, and visit the houses,” Spiegel said.

More information: Zhang Y, Cotter DJ, Thamer M. The effect of dialysis chains on mortality among patients receiving hemodialysis. Health Services Research online, 2010.