A prognosis is a prediction of the probable course and outcome of a disease or the likelihood of recovery from a disease. People often think that the doctor knows and can predict how long an ill person will live but is withholding this information from them. The truth is that, generally, no one knows when an ill person will die. Families should not press for exact predictions or rely on those that are offered. Such exact predictions are often wrong because there is so much variation in how long people can live with a disease. Sometimes very sick people live a few months or years, well past what seems possible. Other people die quickly. If a dying person wants a particular person there at the time of death, arrangements may have to accommodate that wish for an indefinite amount of time. Yet, predicting when a person will die of a disease is sometimes necessary. For example, hospice care usually requires a doctor's prognosis of less than 6 months to live.
Rather than asking their doctor “How much time do I have?” or “Am I likely to die within 6 months?,” people might ask for the typical range of survival—the shortest and longest amount of time a person has lived with a similar illness. Another prediction doctors can often make is whether the ill person is now sick enough that they would not be surprised if death were to occur within a year. At that point, life is tenuous, and the possibility of worsening health and likely death lets the person plan to live as fully and comfortably as possible.
Sometimes, doctors offer hope by describing remarkable recoveries without also mentioning the high likelihood that most people who have such serious conditions will die much more quickly. Gravely ill people and their families eventually find this "hope" to have been misleading and belittling. Instead, ill people and their family members are entitled to the most complete information available and the most realistic prognosis possible. However, they may have to clearly express their preference for such information over an excessively optimistic account.
Symptoms progress differently with different diseases. For a person dying of cancer, energy, function, and comfort usually decrease substantially only in the last month or two before death. The person then is visibly failing, and the fact that death is near becomes obvious to all. Other diseases, such as Alzheimer's disease, liver failure, and kidney failure, follow a steady decline from the beginning. Severe heart disease and chronic obstructive pulmonary disease cause a steady decline, but with episodes of serious worsening. These episodes are often followed by improvement, but usually death comes within a few days of being stable.
Last full review/revision October 2007 by Joanne Lynn, MD, MA, MS