For patients on Medicare to be eligible for hospice care, they have to be expected to live for less than six months. Hospices have a hard time predicting survival for people with dementia, and less than 1 percent of hospice patients in the United States have dementia as their main medical issue. Public-health researchers at Harvard, the University of Michigan, and the Ann Arbor (Mich.) VA Medical Center used data on some 11,000 nursing home patients to develop a way to predict death in patients with dementia.

What the researchers wanted to know: How likely are people with advanced dementia to live for six months or more?

What they did: The researchers used a government data set on nursing facilities that are certified by Medicare or Medicaid. Those facilities have to report on their residents' health when they're admitted and every quarter after that. For this study, they analyzed data on people who were 65 or over, were diagnosed with dementia, and had severe cognitive impairment. They used the data to make up a computer model of residents' characteristics and how likely they were to die within six months, then checked the model on another set of residents.

What they found: The model worked better than the guidelines usually used to predict the chances that someone with advanced dementia will die in the next six months. Characteristics that increase the risk of dying in six months include being male, older than 83, totally dependent on other people, and on oxygen.

What it means to you: It's possible to predict how likely a person with advanced dementia is to die in the next six months. But this is tricky stuff, and it works on percentages—someone who has a good chance of dying is still perfectly capable of living on. So, is it better to enroll more people in hospice care even though some could live for years, which is expensive, or to exclude people but have many die without hospice care?

Caveats: Everyone in the study was a new arrival at a nursing home, so the model might not hold true for people who'd been in a nursing home for longer or who live somewhere else.

Find out more: The National Hospice and Palliative Care Organization http://www.nhpco.org/

Read the article: Mitchell, S.L., Kiely, D.K., Hamel, M.B., Park, P.S., Morris, J.N., and B.E. Fries. "Estimating Prognosis for Nursing Home Residents With Advanced Dementia." Journal of the American Medical Association. June 9, 2004, Vol. 291, No. 22, pp. 2734–2740.

Abstract online: http://jama.ama-assn.org/