Harold, 79, had advanced Alzheimer's. He couldn't walk because he had lost his sense of balance and routinely fell. He wore diapers because he couldn't control his bowels. He didn't recognize family members. When he slipped into a coma, he was hospitalized.

His daughter Doris reports, "One doctor after another doctor after another doctor would come in and my poor mother didn't know what to do. 'Try this!' 'Try that!' But all of his systems were failing."

Doris wrote about her father's situation on Facebook, and friends offered her many opinions about what to do. Finally, after her father had been in a coma for eight weeks, she spoke to her mother about what one of them had said: What quality of life did Harold have before this last episode? What purpose did all of these last-ditch treatments serve? Could they take him home and allow nature to take its course? Could they look into home hospice care?

Her mother, Beverly, was overwhelmed by the fact that she was losing her husband and wracked by uncertainty about what to do. Harold's doctors fiercely resisted Doris' proposed plan.

She notes, "Their position was, 'No, no, no, no! We'll try this one more thing!'"

Finally, Beverly realized that Harold wasn't going to wake up, and that even if he did, he had a terminal disease and wasn't going to be restored to his former self no matter what treatments he got. She decided, with support from Doris and other family members, to take Harold home.

Harold's family got a great deal of help from hospice services, and created a warm and loving environment for him. They talked to him, even though he wasn't conscious. They told stories and played his favorite music in a setting -- his home -- that he knew and loved. And two weeks later, still at home, he passed away surrounded by his family.

But Harold had spent months of his life in the artificial environment of a hospital, getting futile treatment after futile treatment, in a process that was also physically, emotionally, and financially draining for his family. His wife, Beverly, had gone through months of anguish, trying to decide what the right thing to do was.

Harold had previously discussed with his family and friends what he wanted -- and did not want -- under circumstances like the ones that arose. And he didn't want all those treatments.

So why did he get them?

He hadn't put his wishes in writing.

Beverly didn't have a document that she could show to the doctors that indicated what Harold wanted -- and, just as important, what he didn't want. In effect, she didn't have Harold backing her up in her conversations with his doctors. Without having something that Harold had prepared and signed, it was hard for her to take a stand and reject treatments that the doctors wanted to give him.

When the weather forecast predicts a foot of snow, you might make a point of buying milk, bread and batteries. When you plan to go out of town, you might make a point of doing laundry so that you'll have clean clothes for your trip. If you own a house, you almost certainly carry insurance so that in the unlikely event of some major disaster, you can rebuild your home.

In these and in many other circumstances, you plan ahead.

But very few of us plan for the possibility that we might become so ill or injured that we are unable to make decisions about the medical care we get. An AARP survey of members in one state revealed that "only 17 percent have spoken to a physician" about their wishes for end of life care.

Do you think that you'll die suddenly but peacefully in your sleep -- or alternatively, that you'll die abruptly as a result of an accident or a heart attack? A study in the Journal of the American Medical Association found that only 15 percent of people die sudden deaths. Most of the rest experience some period of decline before they die -- whether months or years.

You can save yourself and people who care about you an enormous amount of grief and harm by planning ahead in case you aren't one of the 15 percent but instead are one of the other 85 percent. And that means putting your wishes for your care in writing. A form called an "advance directive" is designed for this purpose.

The rules for writing advance directives that work well vary a little from state to state. AARP offers an interactive map that links to the specifics for each state at www.aarp.org/relationships/caregiving/info-01-2011/caregiver_map.html. When you click on any state, you will find more information, action steps you can take, blank forms that you can print out and fill in, and other resources to help make this task simpler and clearer.

You might also find it useful to look at a document called "Five Wishes," which is an advance directive form written in very clear, straightforward language with easy-to-understand directions. It can be found at www.agingwithdignity.org/five-wishes.php.

One decision that you will need to make is who to name to act as your agent in talking with doctors if you can't do it yourself. My next column will discuss how to choose an agent -- the best choice isn't always obvious.