What do you do when a letter in a prestigious medical journal has been so routinely mis-cited it’s taken on a life of its own? Like when pharmaceutical companies have used its data to spin their dangerous painkillers as safe, and the resulting overprescription fueled an opioid epidemic now consuming the country?

So this week, the New England Journal of Medicine, which published the original letter in 1980, is issuing a corrective. It’s a new study, a bit meta, from a team led by David Juurlink at the University of Toronto that tracked how the five-sentence letter passed through the game of academic citation telephone to become evidence that opioids are safe for chronic pain. In fact, it said no such thing.

In the 1980s, Hershel Jick, a doctor at Boston University Medical Center, had a database of hospital records that he used to monitor side effects from drugs. Journalist Sam Quinones tells the story in his book, Dreamland: The True Tale of America's Opiate Epidemic. Something, perhaps a newspaper article, got Jick interested in looking at addiction. So he asked a graduate student, Jane Porter, to help calculate how many patients in the database got addicted after being treated with pain medicines, and dashed off a letter to the New England Journal of Medicine. Its brevity was commensurate with the effort involved. Here it is in full:

Recently, we examined our current files to determine the incidence of narcotic addiction in 39,946 hospitalized medical patients who were monitored consecutively. Although there were 11,882 patients who received at least one narcotic preparation, there were only four cases of reasonably well documented addiction in patients who had no history of addiction. The addiction was considered major in only one instance. The drugs implicated were meperidine in two patients, Percodan in one, and hydromorphone in one. We conclude that despite widespread use of narcotic drugs in hospitals, the development of addiction is rare in medical patients with no history of addiction.

He didn’t think much of it. Years later, Jick would tell Quinones, “That particular letter, for me, is very near the bottom of a long list of studies that I’ve done.” And for most of the 1980s, the letter didn’t attract much attention either.

But as it began to accrue citations, its findings also began to mutate. Porter and Jick had only looked at hospitalized patients in regimented settings, but that detail got lost in the push to prescribe opioids to patients at home—an entirely different scenario.

Purdue Pharma, which makes OxyContin, starting using the letter’s data to say that less than one percent of patients treated with opioids became addicted. Pain specialists routinely cited it in their lectures. Porter and Jick’s letter is not the only study whose findings on opioid addiction became taken out of context, but it was one of the most prominent. Jick recently told the AP, “I’m essentially mortified that that letter to the editor was used as an excuse to do what these drug companies did.”

If you don’t track down the original letter, it’s not obvious how brief and narrow its findings truly are. (Until NEJM put its full archives online in 2010, the only way to track it down was to find a physical copy in an academic library.) And it seems like many people didn’t. As Quinones writes in his book, the brief letter became a lot grander in retellings:

One researcher, writing in 1990 in Scientific American, called Porter and Jick an “extensive study.” A paper for the Institute for Clinical Systems Improvement called Porter and Jick “a landmark report.” Then the final anointing: Time magazine in 2001 story titled “Less Pain, More Gain,” called Porter and Jick a “landmark study” showing that the “exaggerated fear that patients would become addicted” to opiates was “basically unwarranted.”

There is a perhaps understandable source of confusion. Scientific journals pride themselves on peer review—where outside experts evaluate research—but the Correspondence section that published Porter and Jick’s letter doesn’t usually follow the same standard. It makes some sense. The Correspondence section usually consists of short letters to the editor or somewhat informal observations from doctors and scientists. Porter and Jick’s letter appeared alongside others like, “Bacteriuria in Schoolgirls” and “Problems with Peppermint-Flavored Lidocaine.” (Another piece of old Correspondence in NEJM infamously launched an unfounded panic over MSG in Chinese restaurants.)

A spokesperson for the journal says that the Correspondence section today is subject to peer review on a case-by-case basis, but it is unlikely that the original Porter and Jick letter was peer reviewed. That’s not to say that Porter and Jick’s finding would not have passed muster, or that it is not useful in hospital settings. But the NEJM has built up considerable prestige by publishing truly landmark peer-reviewed studies, and that halo of prestige gave even this brief letter outsized importance. Published in NEJM? Sounds legitimate—especially if you don’t read the actual letter.

Citations of the letter have fallen in recent years, as doctors have seen firsthand just how addictive opioids can be. On NEJM’s website, the Porter and Jick letter now has an editor’s note that reads, “For reasons of public health, readers should be aware that this letter has been ‘heavily and uncritically’ cited as evidence that addiction is rare with opioid therapy.” The note then links to the new study published this week. It’s the only time the current editor, Jeffrey Drazen, has appended such a note in his 17-year tenure.

The outsized influence of the Porter and Jick letter is no secret, but this study sets it in the formal scientific record—in the same journal where it all started.