BAKERSFIELD, Calif. -- A growing number of the 400,000 Americans currently on dialysis are over 80 years old.

Though most elderly patients with kidney failure have a limited life expectancy, many doctors assume that treating the symptoms of their kidney failure with dialysis will improve their quality of life, even if it cannot extend their life expectancy.

But new research from Stanford University has suggested that the opposite is true.

Researchers compared nursing home patients' ability to care for themselves before and after dialysis treatment and found that the patients experienced a significant decline in their ability to perform simple daily tasks, such as feeding themselves, getting dressed, or brushing their teeth, after starting dialysis.

In fact, in the first year of dialysis, only 13 percent of the more than 3,000 patients they followed maintained the level of functioning they had had in the previous year.

In the future, researchers said that they hope that doctors and patients will take into account all the drawbacks of dialysis treatment for elderly patients, including its effect on their everyday functioning and quality of life.