At least one-third of hospital patients older than 70 leave more frail than when they arrived, and many become too weak to go home. Nursing home care or rehabilitation often are needed, and even then, research suggests more than two-thirds remain weaker a year after being in the hospital.

Elder-care experts challenge the idea that this decline is an inevitable part of growing old. They say conventional hospital care focusing on treating disease rather than preventing frailty contributes to the problem.

"Non-medical people say, `Grandma went to the hospital with pneumonia ... and she was never the same again," said Dr. Kenneth Covinsky, a geriatrics specialist at University of California at San Francisco. "Pneumonia is a serious illness, but it is treatable" and should not leave patients disabled.