SYRACUSE, N.Y. - New York doctors prescribe more opioid drugs if they get payments, free meals and other gifts from prescription painkiller manufacturers, according to a study.

The 3,389 New York doctors who received more than $3.5 million in payments from opioid manufacturers between 2013 and 2015 prescribed a lot more of the drugs than doctors who did not get payments, the study shows.

The study by the New York State Health Foundation looked at how opioid prescribing for Medicare enrollees changed after doctors got gifts and speaking or consulting fees from pharmaceutical companies.

It found that for every $1 doctors get in payments, they prescribe at least $10 more in additional opioids.

"Manufacturers are getting a lot of value from these financial relationships with doctors," said Mark Zezza, the foundation's director of policy and research.

New York and the nation are experiencing an opioid overdose epidemic. Opioids include prescription drugs such as Oxycontin and illicit drugs like heroin.

The study, based on data obtained from Medicare, does not identify New York doctors who got opioid-related payments.

The study found a correlation between the size of payments doctors get and the amount of opioids they prescribe.

Doctors who got $20 or less in payments wrote opioid prescriptions worth $34,000 over the two-year period. Those who received between $20 and $50 prescribed almost $50,000 worth of opioids, while a small group of doctors who got payments of more than $10,000 prescribed more than $1.24 million in opioids.

While the study showed a clear link between payments and increased prescriptions, it could not determine if any of the prescribing was inappropriate, Zezza said.

INSYS Therapeutics made $1.9 million of the opioid-related payments to New York doctors, more than any other drug company. INSYS makes Subsys, a spray form of fentanyl approved by the FDA for use by cancer patients.

New York and other states are accusing the company in lawsuits of marketing the drug for broader use beyond cancer patients and downplaying its risk of addiction.

Purdue Pharma, which makes Oxycontin and other opioids, made more than $591,000 in payments.

It is being sued by Onondaga, Oswego and many other counties across the state that have accused the company of downplaying the risks of its drugs.

"Spending by drug companies may be fueling the epidemic," David Sandman, the foundation's president, said in a prepared statement. "Policymakers and law enforcement should take a hard look at these financial entanglements."

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