A new study conducted by researchers at the University of Pittsburgh found that US counties that receive more opioid-related pharmaceutical industry payments had more opioid-related deaths.

The top three counties with the highest concentration of opioid-related deaths were Harrison County in Kentucky and Cabell County and Wayne County in West Virginia.

In total, the pharmaceutical industry paid $9.8 million to 31,532 medical providers in 2016.

In the past few years, the role that pharmaceutical companies played in fueling the opioid crisis has started to come to light.

The New York Times unveiled in an investigative report in May that Purdue Pharma knew its opioid drugs were being abused in 1996, shortly after they came on the market. But the drugmaker concealed the information and continued to market its drugs until the early 2000s.

Opioid overdoses caused more than 42,000 deaths in the US in 2016, and 40% of those deaths involved prescription drugs, according to the Centers for Disease Control and Prevention. Opioid-related deaths increased 345% from 2001 to 2016, according to a study published in June in JAMA.

Read more: 'The pain takes over and it's torture': Inside the search for new ways to treat pain as America fights against opioid addiction

Now, a new report published in the Journal of General Internal Medicine found that US counties where doctors got more payments from opioid manufacturers also had more opioid-related deaths. The researchers, from the University of Pittsburgh, compared government data on overdose deaths with payments data collected by the Centers for Medicare & Medicaid Services.

"This is provocative data that can really serve as a substrate for us to do more work," said Dr. Benjamin Davies, one of the authors of the study and an associate professor of urology at the University of Pittsburgh School Of Medicine.

In 2016, the pharmaceutical industry doled out nearly $10 million to US physicians for opioid-related marketing. That includes speaking and consulting fees, meals, travel, honoraria, and education. As the researchers mapped the spending pattern against the map of opioid-related deaths, they found that the counties with the highest overdose death rate per capita also had the highest opioid-related industry payments, adjusted for population.

The study found that the top three counties with the highest concentration of opioid-related deaths were Harrison County in Kentucky and West Virginia's Cabell County and Wayne County.