New York ? A significant number of the elderly — more than one in four — will eventually need someone to make end-of-life decisions about their medical care, a new study suggests.

The results illustrate the value of people making their wishes known in a living will and designating someone to make treatment decisions for them, the researchers said.

In the study, those who spelled out their preferences in living wills usually got the treatment they wanted. Only a few wanted heroic measures to prolong their lives.

The researchers said it’s the first accounting of how many of the elderly really end up needing medical decisions made for them.

Last year, end-of-life care became embroiled in the health care reform debate. A provision in the legislation would have allowed Medicare to pay doctors for counseling patients about end-of-life issues like living wills.

Critics labeled the counseling “death panels” and the proposal was eventually dropped before the researchers could get their report out. They had pushed to complete the study because of the national debate, but it took time to get it published, said the study’s leader, Dr. Maria Silveira. She teaches at the University of Michigan and does research for Veterans Affairs.

The study is in today’s New England Journal of Medicine.

The researchers concluded that advance directives — living wills and health proxies chosen to make end-of-life decisions — are “important tools for providing care in keeping with patients’ wishes.”

The use of these directives has increased in the U.S. despite debate about their effectiveness. For the past two decades, hospitals and facilities that take Medicare patients are required to provide information on them.

A living will states a person’s choices for treatment if he becomes incapacitated, but critics complain they are too vague to be helpful. A health care proxy names another person — usually a relative or friend — to make medical decisions if needed. Many people have both.