INDIANAPOLIS -- There may have been as many as three times more heroin-related deaths in Marion County over the past six years than the official numbers let on, according to a study just published by an IUPUI professor.

Assistant Professor Brad Ray studies substance abuse at IUPUI's School of Public and Environmental Affairs. He and his team looked at nearly 1,200 overdose deaths in Marion County between 2010 and 2015 to determine how they were being categorized – and whether heroin played a bigger role than the numbers suggest.

In a study published in the Journal of Urban Health, Ray's team says the answer to that question is likely yes, because of the way people who die with multiple drugs in their system are coded by the coroner.

"They'll code it as, if it was just heroin, they'll say heroin caused the death," Ray said. "If it was heroin, oxycodone and alcohol, then they might say it was an opioid-related death. If it was heroin, cocaine, marijuana, alcohol, benzodiazepines, then they would say it's a poly-drug death."

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Out of 1,199 accidental drug-overdose deaths in Marion County from 2010-2015, the Marion County Coroner's Office classified 141 as caused by heroin.

Ray's team looked at those reports and found that as many as 455 of those deaths were likely heroin-related.

Ray stressed that the deaths are already being counted, but that it's important from a public health policy perspective to know whether an opioid-related overdose is caused by pills – oxycodone, for example – or by heroin or fentanyl.

"We want to know that people are not just dying of opiates – we want to know if it's heroin," Ray said. "Because that's going to be different in how we intervene. And whether or not it's fentanyl, because that's going to be different in how we want to intervene and look at that."

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From 2010-2015 in Marion County, Ray's team found that total opioid-related overdoses per year doubled, from 129 in 2010 to 260 in 2015. But Ray says his research shows that increase was driven primarily by a 400-percent increase in heroin-related deaths – an increase from 22 in 2010 to 111 in 2015.

Data from Indianapolis Emergency Medical Services shows the number of doses of the anti-overdose medication naloxone has also skyrocketed since 2010. Read more about that here.

He says that info is one of the most important takeaways of the study.

"What we're seeing here in Indiana is in 2012 and 2013 we really started to regulate our prescription drugs. We saw some crackdowns on pill mills, we saw reductions in prescribing because of new regulations, so we saw this reduction in pills," Ray said. "And so as a result we saw an iatrogenic effect (an illness caused by medical treatment), which was that there were people moving from pills to heroin. It's a cheaper alternative. I mean, it's $60 for a pill, and $10 for a bag of heroin. If you think about this, with pills, you know what you're getting. You're getting the same pill every time. You know exactly what's in there. But with heroin, you don't know what you're getting. That variable effect is why people are dying. They don't know how much they can take, how much they can handle, and what's in there. And so that heroin and fentanyl – those illicit substances – are largely what's driving our increases in overdoses. And for that, we need treatment. We need to really, in this state, rethink some of our treatment."

A bill sponsored by state Sen. Jim Merritt (R-Indianapolis) currently under consideration by the General Assembly would address some of Ray's suggestions. The bill, SB 74, would require coroners investigating overdose deaths to perform a "drugs of abuse" panel to detect the presence of Schedule I and II drugs, like heroin and fentanyl. The Indiana State Department of Health would then receive those results.