THURSDAY, Aug. 8 (HealthDay News) -- Dialysis patients whose doctors have fewer patients are less likely to die than those whose doctors have more patients, according to a six-year study.

Researchers looked at survival rates between 2001 and 2007 among dialysis patients cared for by 41 kidney specialists (nephrologists) in an urban California region. The nephrologists had between 50 and 200 patients.

Nephrologists whose patients had the best survival rates had significantly lower patient caseloads than those whose patients had the worst survival rates. For every additional 50 patients under a nephrologist's care, patients had a 2 percent higher risk of dying during the study time frame.

The study appears in an upcoming issue of the Journal of the American Society of Nephrology.

"Our data suggest that patients receiving care from nephrologists with lower caseloads may have greater survival," said Dr. Kamyar Kalantar-Zadeh, of the University of California Irvine Medical Center, and colleagues in a journal news release. "Such data may help direct health policies and guidelines more effectively."

Although the study tied a nephrologist's smaller caseload to a reduced death risk among patients, it did not establish a cause-and-effect relationship.

The researchers said additional studies are needed to confirm these findings and to investigate how kidney doctors' caseloads influence patient survival. They added that further research also is needed to determine the patient caseload threshold above which the benefits of a doctor's increased experience are outweighed by a decrease in quality of care and patient outcomes.

More than 1.5 million people worldwide undergo kidney dialysis, according to the news release.

More information

The National Kidney Foundation has more about kidney dialysis.