Tens of thousands of people fatally overdose each year on opioids and other drugs. Sometimes medical examiners label them accidents, and sometimes they don't know what to call them.
But where humans waver, a computer program using a kind of artificial intelligence finds many are likely suicides -- possibly a third of them, according to a study by a Johns Hopkins School of Medicine researcher who partnered with a Utah high school student.
The information could bring sharper focus to the scope of epidemics of opioid abuse and suicides, as well as the need for resources.
"If we're trying to prevent deaths in the community, we have to figure out why people are dying," said Dr. Paul Nestadt, the Johns Hopkins assistant professor of psychiatry and behavioral sciences who was one of the study's authors.
"If people are dying by accidental overdose, the best interventions -- naloxone availability and treatment in the community for addiction -- are different from those for suicide, like the availability of hotlines and antidepressants," he said.
There have been other attempts to identify the suicides hidden in the overdose numbers. This study, recently published in the journal Suicide and Life-Threatening Behavior, backs up some of those findings. The Hopkins research, however, may be the first attempt to use so-called machine learning to verify the estimates.
Under the model, the researchers entered information about overdose deaths in Utah from 2012 to 2015 into an algorithm. The data included age, sex, race, history of mental illness, and stressors like job loss, Nestadt said. The algorithm, taught to recognize the importance of risk factors, combined the data to determine the probability that a case was a suicide.
Few overdose cases nationally are labeled suicides because, absent a suicide note, examiners are often unsure of the drug user's intent. That's led to overdose cases largely being called accidents or "undetermined."
Overdoses quadrupled over two decades to about 70,000 in 2017, mostly due to opioids that include prescription painkillers and illicit heroin and fentanyl. Suicides have risen by about a quarter to 47,000 in about the same time frame.
"There are two epidemics, suicide and opioids," said Dr. Ian Rockett, who has been researching the undercounting of suicides for a decade. "They tend to be treated separately, when there is considerable overlap."