A sentence in a Health section article yesterday on the effect of Medicare's Diagnosis Related Groups on hospitals was incorrect. It should have read: If a hospital spends less than the DRG reimbursement, it makes money; if it spends more, it loses. A different Health article inaccurately reported which of his guns Ernest Hemingway used to commit suicide. He used a shotgun, not the gun his father had used to kill himself.

Although suicide among the young has drawn most of the attention recently, rates are even higher among old people. Suicide rates in American males rise steadily with age, and older men have the highest suicide rate of any group in the nation.

"It's a critical problem," said Dr. Robert Butler, former director of the National Institute on Aging and now chairman of the geriatrics department at Mount Sinai School of Medicine in New York.

People 65 and older make up about 12 percent of the population, but they account for between 20 and 25 percent of the suicides, Butler said.

The most widely publicized recent example is low-fat diet promoter Nathan Pritikin, who slashed his wrists and bled to death last week in an Albany, N.Y., hospital.

Pritikin, 69, founder of the Pritikin Longevity Centers in California, Florida and Pennsylvania, was suffering complications from a flare-up of leukemia. He had been admitted under an assumed name Feb. 11 to Albany Medical Center Hospital, where he was receiving chemotherapy.

Treatment of the leukemia, which had been in remission for more than 20 years, led to what a Pritikin center spokeswoman in California called a "chain reaction of side effects," including anemia, kidney failure and liver problems. Pritikin was reportedly despondent about his deteriorating condition.

"It's rather astonishing that a man who established a longevity center should take his life in such a violent way," said Derek Humphry, director of the Hemlock Society in Los Angeles, which seeks legalization of suicide for mentally competent patients who choose to end their lives.

In 1982, the overall suicide rate in the United States was 12.3 per 100,000, according to the National Center for Health Statistics. The rate among people 65 and older was 18 per 100,000, or 50 percent higher, although it has been declining in recent years for reasons that still baffle the experts.

And the comparable rates were 31 per 100,000 men aged 65 to 74, 45 per 100,000 men aged 75 to 84, and 50 per 100,000 men 85 and older -- quadruple the national rate.

The rate is several times higher in men than women, whose suicide rate peaks in middle age and then declines steadily.

Of course, the vast majority of older people -- including those who are sick, lonely, out of work and chronically depressed -- do not take their own lives. Even those who fit the pattern of risk for suicide, said Ronald Maris, a sociologist at the University of South Carolina, usually avoid it, whether out of religious convictions, family obligations, a reverence for life, fear of suicide's stigma on survivors or because they simply cannot tolerate violence.

Precise data on suicide are scarce, because a suicide is often difficult to distinguish from an accidental or natural death, particularly in the elderly.

The fact is that no one knows exactly how many people take their own lives, but most experts assume that suicide is underreported. Families and doctors often cooperate in disguising less-than-obvious suicides, particularly in older persons, out of fear of the stigma attached.

Older people are more likely than young people to carry out a threatened suicide.

"When an older person threatens suicide," Butler said, "they mean it. And if they attempt it, more of them are going to carry it out, relative to younger people."

"The elderly are usually deadly serious when it comes to suicide," said John McIntosh, a psychologist at Indiana University at South Bend.

There are several patterns of suicidal older people, depending on their health, financial situation and family history, said sociologist Maris.

"But if I had to pick one prototypical case," Maris said, "it would be somebody who is isolated socially, clinically depressed, feeling hopeless and somewhat angry."

Often, he said, they also are in failing health, have violent means available, such as a gun, and have a history of suicide in the family.

Ernest Hemingway, for example, killed himself with a gun his mother sent to him -- the very gun his own father had used to commit suicide.

Despite a common misconception, Maris said, suicide usually results not from an impulsive reaction to a single crisis but from a lifelong accumulation of problems and feeling -- such as loneliness, ill health, anger, depression, alchoholism. That is particularly true in aged people.

Given such problems, elderly people may feel more desperate about what they see as the lack of alternatives available to them, said Dr. Nathan Billig, director of the geriatric psychiatry program at Georgetown University Medical Center.

Factors such as alcoholism, living alone, physical illness and depression -- especially in combination -- put an elderly person at higher risk of suicide, he said.

"All of those are setups for feelings of helplessness and hopelessness that can -- but do not necessarily -- lead to suicide," Billig said.

Recognition of suicidal warning signals in the elderly is difficult, because older people tend not to use the word "depression" much and often keep such feelings to themselves.

"They often don't let us know about it unless we ask," Billig said. An older person's depression may be "camouflaged" in complaints about physical ailments, such as persistent headaches or arthritis.

In some ways the terminal cancer patient, such as Pritikin, is a classic example of a potential suicide, Maris said, because after a while even medication won't help.

"It may help you have a better night's sleep, but you know you're not going to get better," he said. "You're never going to get well."

The Hemlock Society was founded in 1980 to help people make choices about how they would deal with terminal illness. The motto of the society, which has 11,000 members, is "Good life, good death through control and choice."

Director Humphry's book "Let Me Die Before I Wake," which describes methods and recommended drug dosages for a nonviolent, painless death, has sold 40,000 copies.

"We believe people should be able to request help in dying, under carefully guarded circumstances," said Humphry. "We believe someone who is dying and mentally competent should be able to say to a doctor: 'I can't take this anymore. It's unbearable. Please leave me the overdose.'

"But because you can't make that request, people do terrible things to themselves -- such as Pritikin slashing his wrists and double killings by elderly couples who have lived together for 30 and 40 years."

Pritikin's death prompted hundreds of people to sign up for his controversial health program, said a spokeswoman for the California center.

For fees of up to $6,000, patients spend several weeks of intensive education, exercise and strict dieting at the Pritikin centers. The diet -- low in fat, sugar and salt -- is the basis of what has come to be known as the Pritikin Program, promoted heavily through the centers, sales of Pritikin-brand foods and a series of best-selling books.

Pritikin and his supporters claimed that the diet program could prevent and reverse heart disease. But critics, while supporting the general goal of reducing dietary fat, said the diet was needlessly strict and some of Pritikin's claims unproven by scientific studies.

Experts agree that more research is needed on suicide in all ages, but particularly in the aged, since it is most prevalent in that group.

High suicide rates among the elderly have been largely overlooked amid understandable concern about rising suicide rates among young people, Butler said.

Americans tend to view adolescent suicide as more tragic and terrible than suicide in the old, said pyschologist McIntosh.

"We don't seem to be as broken up about suicide in an old person," McIntosh said. "It's almost as if it's okay. We are a society where youth is valued more than old age."