Amy Winehouse’s death from alcohol poisoning in 2011 gave rehab advocates a chance to cluck. The demise of the singer who so publicly slammed their profession—“I just need a friend/ I’m not gonna spend 10 weeks/ Have everyone think I’m on the mend”—was an irresistible chance to offer their “if onlys.” If only she had reached out to us. If only she had gotten help.

This is what makes Asif Kapadia’s Amy, one of five nominees for Best Documentary Feature this year, so interesting. Winehouse did seek help. She even attended rehab, the very institution she dismissed as a PR charade, at least twice. But rehab didn’t save her. Nor did it save Cory Monteith, Whitney Houston, or many others.

The life and death of Amy Winehouse isn’t a lesson in celebrity hubris. It’s an example of how poorly researched our system of addiction medicine really is. We spend $13 billion every year on addiction treatment with very little proof that it works. Studies on the efficacy of inpatient rehab are contradictory, and those that find strong, positive results are limited to certain kinds of patients who may not reflect the general population. The system seems to work for some people, but we have no idea why it works for them or, more importantly, why it fails so many others.

There is a maxim used in other fields of medicine, that if you can choose from among many treatments for a single disorder, none is very effective. Once doctors develop an effective treatment, the alternatives fall away. Nowhere is this problem more evident than in addiction medicine. The most venerable treatment regime, the 12-step program, has limited supporting data, despite decades of history and millions of patients. Prescription drugs to treat addiction likewise perform inconsistently in studies.

“Rehab,” often used to refer to inpatient or residential addiction treatment, is especially problematic. Rehab centers have the feel of pre-modern sanatoria. Most (but not all) are based on the 12-step program, but they have varying add-on philosophies and “treatments,” depending on the patient’s financial health.

Consider the swanky Cirque Lodge in Sundance, Utah, rehab of choice for celebrities such as Demi Moore and Lindsay Lohan. For a reported $1,000 per day, patients heal through heli-hiking (“Alcohol and drug rehab takes on a different perspective at 10,000 feet!”) and can take on the largest indoor ropes course “anywhere in the alcohol and drug rehab industry.” As far as I can tell, there have been few randomized trials on the efficacy of heli-hiking for alcoholism. And if you’re choosing an addiction treatment program based on the size of its ropes course, you probably haven’t hit rock bottom.

Overpriced woo, however, is only a symptom of a larger problem. Our addiction care system is a Wild West show, according to a 2012 Columbia University report. Addiction counselors, who do the majority of the day-to-day work at most rehab centers, aren’t required to have even a bachelor’s degree in 44 states. The doctors who sometimes supervise them receive little or no addiction medicine training during medical school, and there are no residency programs for the field. (Most doctors will tell you that residency, the three- to five-year practical training program that follows medical school, is where they really learned their trade.) Interested parties can pursue an addiction medicine fellowship, typically in the form of a one-year program tacked on at the end of any old medical specialty. Not to pick on Cirque Lodge, but its medical director began his career as a pulmonologist.

This mess wouldn’t be so objectionable if it were a mess that worked, but no one knows if it does. What data we have on inpatient rehab is limited to very specific and unusual populations. Doctors who themselves suffer from addiction, for example, are required by law to undergo treatment and regular testing for a five-year period—a very convenient situation for researchers who want to track their progress. Studies of recovering doctors suggest that rehab works pretty well—about 80 percent stay drug-free during the testing period. But this is a highly educated, highly motivated group of people with much to gain and everything to lose from a single slip-up. Do they really represent the general population of substance abusers, or the celebrity case studies?

Lisa Merlo, a University of Florida psychiatrist who has conducted much of the physician-addict research, says we’re still trying to figure out how to study other groups. “If an addict is doing poorly, they don’t come in for care. It’s a difficult population to follow,” she explains. Addicts are nothing like cancer patients, who actually want to come back for follow-up care.

In light of these evidentiary challenges, it’s difficult to justify rehab centers’ enormous expense. A 2003 study found that rehab facilities cost approximately $15,000 per successfully treated patient, compared with about $6,000 for outpatient treatment. Since most studies—which, admittedly, have the same problems tracking patients—suggest inpatient rehab is no better than outpatient treatment, rehab seems like an unnecessary luxury. Especially when you throw in the heli-hiking.

Politicians have been lining up lately to throw money at addiction medicine. Earlier this year, Medicaid raised the possibility of funding inpatient addiction research, reversing decades of resistance. There’s nothing wrong with giving it a try, but that money ought to come with some heavy strings attached. Participating institutions should have to devise convincing strategies to follow their patients for at least five years so they can report reliable data on outcomes.

The irony of Amy Winehouse going to rehab (twice) was irresistible. As Kapadia documents, everyone from late-night hosts to her close friends had a nice laugh at her expense. The far greater absurdity, however, is the postmortem claims by addiction specialists that they could have saved her. Her death stands for how little we understand about substance abuse and recovery. Breaking addiction is hugely challenging, but it’s time to meet that challenge with rigorous science. Ropes courses optional.

Read more in Slate about the 2016 Oscars.