Story highlights A 1980 letter has been frequently cited as proof of the safety of long-term opioid use

One of the authors is quick to point out that the letter was misrepresented

Meanwhile, municipalities are stepping up in the fight against opioid abuse

(CNN) Every day, 91 Americans die from an opioid overdose. Drug overdoses overall -- most of them from opioid painkillers and heroin -- are the leading cause of accidental death in the US, killing more people than guns or car accidents. In fact, while Americans represent only about 5% of the global population, they consume about 80% of the world's opioid painkillers. But how did we get to this point?

there were only four cases of addiction. Many public health experts point to a simple five-sentence letter to the editor published in a 1980 edition of the New England Journal of Medicine. The 101-word letter, titled "Addiction Rare in Patients Treated with Narcotics," was signed by Jane Porter and Dr. Hershel Jick of Boston University, who said that of their 11,000-plus patients treated with narcotics,there were only four cases of addiction.

And although this letter provided no further evidence and was not a peer-reviewed study, it has often been cited as proof of the safety of prescribing long-term narcotics for chronic pain.

since its publication. The analysis found 608 citations of the initial letter as of May 30, 72% of them pointing to it as proof that addiction was rare among long-term narcotic users. This week, the journal published yet another letter to the editor, this one an analysis from researchers at the Institute for Clinical Evaluative Sciences of how frequently Porter and Jick's letter has been cited by other researchers and physicians in studies and journalssince its publication. The analysis found 608 citations of the initial letter as of May 30, 72% of them pointing to it as proof that addiction was rare among long-term narcotic users.

Dr. David Juurlink, one of the researchers involved in the analysis, wrote in an email that the "5-sentence letter to the editor in medicine's most prestigious journal was leveraged as proof that opioids could be used safely over the long term, even though it offered no evidence to support that claim. It's clear that many of the authors who cited it hadn't actually read it."

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