The slippery slope is an argument frequently invoked in the world of bioethics. It connotes the notion that a particular course of action will lead inevitably to undesirable and unintended consequences. Saying no to the original action, even if that act is moral in itself, may, in light of the slope that looms, be the ethical thing to do.

Slippery slope arguments have been especially pervasive in discussions of euthanasia, in which physicians actively end patients’ lives, and physician-assisted dying (or physician-assisted suicide), in which physicians supply medications to patients that enable them to end their own lives.^1,2 The concern, fueled by the German experience with racially motivated euthanasia in the last century, has been that approving either of these procedures for a few individuals will inevitably lead to overuse and abuse.

In this issue of JAMA Internal Medicine, Snijdewind et al³ and Dierickx et al⁴ report recent findings about physician-assisted suicide and euthanasia from the Netherlands and Belgium, respectively. Although neither article mentions the term slippery slope, both studies^3,4 report worrisome findings that seem to validate concerns about where these practices might lead. These findings, and other recent data regarding the speeding of patients’ deaths,^5– 8 make this a key moment to revisit efforts in the legalization of assisted dying in the United States and elsewhere, and, specifically, the role of the medical profession.

Snijdewind et al³ report data from the End-of-Life Clinic, an organization established in the Netherlands in 2012 to consider euthanasia or physician-assisted suicide requests from patients whose primary physicians turned down a request or declined to participate. Although not legal, speeding of death is tolerated in the Netherlands for patients with unbearable conditions, without prospect of relief. The End-of-Life Clinic is thus a second opinion for patients who claim this status and who seek aid in dying.

In total, 645 people applied to the clinic during a 1-year period. Physicians approved 162 requests (25.1%), rejected 300 (46.5%), and reached no decision in the remaining cases. Some of the rationales given are reassuring. For example, requests characterized by psychological as opposed to physical suffering were more likely to be rejected, as were requests by individuals who lived alone. Thus, fears were mitigated that solitary, depressed individuals with potentially reversible conditions might successfully end their lives.

However, other findings are very worrisome. Most notably, 6.8% of those who successfully obtained euthanasia or physician-assisted suicide were categorized as tired of living. A total of 3.7% reported only psychological suffering. Although it is possible that such people were suffering unbearably and not apt to improve, the term tired of living is vague and thus disturbing. Similarly, 49.1% of those whose requests were granted characterized part of their suffering as loneliness. Loneliness, even if accompanied by other symptoms, hardly seems a condition best addressed by offering death. Finally, that 53.7% of approved requests are among those 80 years and older raises red flags. Is old age itself being conflated with suffering? Is it possible that there is a not-so-subtle ageism here among the physicians approving such requests?

The validity of these concerns is strengthened by reports that 1 (3.3%) in 30 people in the Netherlands died by euthanasia in 2012, roughly triple the percentage in 2002 when the practice was first decriminalized.⁹ According to a recent article in Newsweek, the definition of unbearable suffering in the Netherlands has been expanding every year.⁶

As Dierickx et al⁴ report, the rate of euthanasia is also increasing in Belgium where the practice is fully legal (although physician-assisted dying is not officially condoned). Whereas 1.9% of all deaths in Flanders, Belgium, in 2007 were by euthanasia, the percentage increased to 4.6% by 2013; this represents 1 in 22 deaths—even higher than the 1 in 30 deaths in the Netherlands. Their data also indicate that the percentage of euthanasia requests that were approved in Flanders increased from 55% in 2007 to 77% in 2013. As in the Netherlands, there are safeguards in place in Belgium; patients must have constant and unbearable physical or psychological suffering and make repeated, voluntary requests.

In Belgium, physical suffering without prospects of improvement was the most common reason given for granting euthanasia. However, as is the case in the Netherlands, there are worrisome trends. Applicants were allowed to list tiredness of life in their requests in 2013 (but not in 2007), and the fastest-growing populations receiving euthanasia include those potentially vulnerable to discrimination and stigma, such as women, people older than 80 years, those with less educational attainment, and nursing home residents. A June 2015 article⁵ in the New Yorker corroborated these concerns, telling the story of a depressed woman who was chatting and laughing on the way to her euthanasia appointment and reporting that other Belgians had been euthanized for such conditions as autism, anorexia, and chronic fatigue syndrome.

Both of these studies are well done but contain gaps. For example, the Netherlands data are limited in that the reported diagnoses were those offered by patients, not those ultimately made by the physicians who said either yes or no. In both studies, there are no descriptions of specific cases, so it is hard to know exactly what the physical and psychological suffering of the individuals in question actually looked like. Similarly, we do not know what those who identified themselves as lonely or tired of living were experiencing. Had they and their physicians exhausted all options that might have restored some of their happiness? Could and should public policy do more for them?

The slippery slope is not always a persuasive argument. However, these data and the other recent reports^5– 8 require that it be taken very seriously. On the one hand, some of the trends may be welcome. To the degree that there is unremitting suffering among these patients and physicians at the End-of-Life Clinic and in Flanders are providing expanded access, their efforts may be ethically defensible. On the other hand, though, the increasing rates of euthanasia may alternatively represent a type of reflexive, carte blanche acquiescence among physicians to the concept of patient self-determination. Or worse, is it simply easier for physicians to accede to these sad and ailing patients’ wishes than to reembark on new efforts to relieve or cope with their suffering? As one Dutch ethics professor has said, “The risk now is that people no longer search for a way to endure their suffering.”⁶ In other words, are the Netherlands and Belgium turning to physicians to solve with euthanasia what are essentially psychosocial issues? And one additional question: Did physicians in the End-of-Life Clinic diagnose unbearable suffering in patients previously not given that diagnosis because they are better diagnosticians or because the clinic was set up by Right to Die NL, a proeuthanasia organization?

Part of the problem with the slippery slope is you never know when you are on it. Is the use of euthanasia or physician-assisted suicide appropriate for 1 of 20 to 25 dying patients? What if the next round of data indicates that the number has increased to 1 of 10 or 15 patients? Careful, independent studies are crucial to ensure that the safeguards put in place in the Netherlands and Belgium are working and that these end-of-life strategies remain ones of last resort for desperate individuals, not the wrong response to frailty and loneliness.

The European data are particularly relevant for the United States. Although proven interventions that ease the suffering of dying patients, such as hospice and palliative care, remain underused, 25 state legislatures and the District of Columbia have considered legislation related to physician-assisted dying during 2015.¹⁰ Versions of physician-assisted dying are already allowed by legislation in Oregon, Washington, and Vermont and by court decisions in Montana and New Mexico. A 2014 Gallup poll found that 7 of 10 Americans believe physicians should be allowed to “legally end a patient’s life by some painless means.”⁶ Meanwhile, the Supreme Court of Canada ruled in February 2015 that terminally ill patients in that country have the right to physician-assisted suicide.

Although the euthanasia practices in the Netherlands and Belgium are unlikely to gain a foothold in the United States, a rapidly aging population demanding this type of service should give us pause. Physicians must primarily remain healers. There are numerous groups that are potentially vulnerable to abuses waiting at the end of the slippery slope—the elderly, the disabled, the poor, minorities, and people with psychiatric impairments. When a society does poorly in the alleviation of suffering, it should be careful not to slide into trouble. Instead, it should fix its real problems.

First published in JAMA Internal Medicine, August 10, 2015. Coauthored with Arthur L. Caplan, PhD.

doi:10.1001/jamainternmed.2015.4086.