Between 1998 and 2006, 456 patients in Oregon received lethal prescriptions. Of those, 292 patients actually used the drugs to kill themselves. That is 0.15 percent of all deaths in Oregon during the same time period.
The practice is more prevalent in the Netherlands. Of the 136,000 deaths annually, 1.7 percent - or 2,400 - are by voluntary active euthanasia and 0.1 percent by physician-assisted suicide.
Legalizing doctor-assisted suicide in Oregon and the Netherlands did not, as some critics predicted, result in disproportionate deaths among the elderly, poor, uninsured, disabled or mentally ill, a study led by the University of Utah shows.
Of 10 "vulnerable" groups examined in the study - which also included women, ethnic minorities, children and people with nonterminal, chronic illnesses - only AIDS patients chose euthanasia at elevated rates.
The study will be published in the October issue of the Journal of Medical Ethics.
It does not speak to the morality of a practice alternately labeled, "patient directed dying" or "mercy killing." Instead, the study is "resolutely, empirically neutral," said lead author and U. bioethicist Margaret Battin.
But it rebuts the popular, and powerful, "slippery slope" argument against euthanasia: The idea that making it legal for doctors to help patients die is incompatible with the role of healer, and could lead to widespread abuse.
Researchers asked: Would vulnerable populations "be pressured, manipulated or forced to request or accept physician-assisted dying by overburdened family members, callous physicians, or institutions or insurers concern about their own profits?"
The answer was no.
To the contrary, the privileged - those with an advanced education and greater financial security - appear more likely to end their lives this way, researchers found.
The study is the first to look at data from Oregon and the Netherlands.
Dutch law does not require that a patient be terminally ill, but that he or she be facing "unbearable, hopeless suffering."
Oregon's law is more restrictive. It allows doctors to prescribe lethal medications to patients who have been diagnosed by two physicians as having a terminal illness and less than six months to live.
The data also cover different time periods, but overlap in striking ways, said Battin.
The median age of those who elect help in dying is 70, seven years below the average life expectancy in both countries. Eighty percent are cancer patients, followed by people diagnosed with Lou Gehrig's disease.
The findings are grouped according to the strength of the data. The evidence was strongest against there being a higher risk for the elderly, women and uninsured.
But the evidence that a greater risk did exist for AIDS patients is equally strong. In Oregon, between 1998 and 2006, only six AIDS patients ended their lives with the help of a doctor.
But that's 30 times the rate of a comparable group of people who died with chronic respiratory disorders, the study says.
That comes as a surprise to Stan Penfold, director of the Utah AIDS Foundation.
Before 1997, AIDS was considered "a death sentence," but treatment has improved and is now widely available, said Penfold. "People can survive pretty well, even those who get on meds late in the progression of their disease," he said.
Battin, a U. philosophy professor and adjunct professor of internal medicine, is a respected scholar, specializing in suicide, death and dying. Most of her research is neutral.
At least two of the dozens of articles and books she has written, however, argue in favor of the legalization of assisted death. Also, Battin is on the advisory board of the Death with Dignity National Center, a nonprofit group that defends Oregon's euthanasia law.
Oregon is the only state where the practice is legal.
Battin would not discuss her views, saying, "There are times when articulation of one's own view is appropriate and times when it's not."
She noted that other researchers who collaborated on the project have opposing opinions. On the team are: public health physician Agnes van der Heide of Erasmus Medical Center in Rotterdam, Netherlands; psychiatrist Linda Ganzini at Oregon Health & Science University in Portland; and physician Gerrit van der Wal and health scientist Bregje Onwuteaka-Philipsen of the VU University Medical Center in Amsterdam.
The study isn't the first to rebut the "slippery slope" argument, a concern cited by the American Medical Association, American College of Physicians and U.S. Supreme Court.
"It keeps popping up, even in the face of nine years of data showing it doesn't happen, because it's a scare tactic," said Death with Dignity director Peg Sandeen.
"It's scary to think the wrong people will die for the wrong reasons."
Stephen Drake, an analyst at Not Dead Yet, a disabled-rights group opposed to euthanasia, claims the study used "soft" data self-reported by doctors.
Proponents of assisted death argue the methodology was peer reviewed.
"It's the most pre-eminent examination of the data with the slippery slope question in mind," said Kathryn Tucker, legal affairs director at Compassion & Choices.
kstewart@sltrib.com