By Pat Anson, Editor

Two studies released this week suggest that pre-existing medical conditions and substance abuse play a strong role in determining whether a patient becomes a long-term opioid user or is hospitalized by an overdose.

The findings could help doctors identify pain patients more likely to develop opioid addiction, instead of flatly assuming that opioids are risky for everyone.

The first study, published in JAMA Surgery, looked at over 36,000 adults who were given a limited supply of opioids to control their pain after surgery. None of the patients had an opioid prescription in the year preceding their operation.

Only about 6 percent of the patients were refilling opioid prescriptions three to six months after their surgery.

The rate didn’t differ significantly between those who had a minor operation and those who had major surgery.

When researchers dug deeper, they found that many of the long term opioid users had similar medical issues. People with arthritis were about 60 percent more likely to keep filling prescriptions, while smokers were about 25 percent more likely. Those who suffered from depression and anxiety were about 20 percent likely to keep taking opioids.

"This points to an under-recognized problem among surgical patients," said lead author Chad Brummett, MD, director of the Pain Research division in the University of Michigan Medical School Department of Anesthesiology. "This is not about the surgery itself, but about the individual who is having the procedure, and some predisposition they may have."

More than 50 million surgical procedures are performed in the U.S. every year. If the study's findings hold true for all patients, researchers say over 2 million people who were "opioid naïve" before surgery could wind up receiving the drugs for months afterward.

Medical Conditions Linked to Overdoses

The second, much larger study looked at a database of over 18 million patients who had an opioid prescription between 2009 and 2013. Over 7,200 opioid overdoses that required hospitalization were identified.  

Researchers found that a previous diagnosis of substance abuse was the single factor most strongly associated with an overdose.  Bipolar disorder, schizophrenia, stroke, renal disease, heart failure and non-malignant pancreatic disease were also strongly associated with overdose risk. 

The risks linked to many of these pre-existing health conditions were so strong they outweighed the risk associated with taking high daily doses of opioids over 100 mg morphine equivalent dose (MED).

“The authors have been able to demonstrate in a very large population there are many risk factors far more important than opioid dose that predict overdose,” said Lynn Webster, MD, a leading expert in pain management and past president of the American Academy of Pain Medicine. 

“I have been lecturing and writing for a decade that dose is less of a contributing factor for overdoses than mental health and history of substance abuse disorders. This study supports what I have been saying.”

The study also identified the prescription opioids most strongly associated with overdose were fentanyl, morphine and methadone. Interestingly, the use of benzodiazepines and antidepressants was riskier than taking hydrocodone, oxycodone and tramadol.   

The study, published in the journal Pain Medicine, was conducted by Venebio, a Virginia-based research group.

"Pain and its management are complex and multidimensional, and the risk of an opioid overdose is likewise dependent on many factors," said Barbara Zedler, MD, lead author and chief medical officer of Venebio. "Primary care professionals express concern about prescription opioid misuse and find managing patients with chronic pain to be stressful. Many feel inadequately trained in prescribing opioids and treating or managing opioid use disorder or addiction." 

Venebio has developed an opioid risk screening tool – called the Venebio Opioid Advisor (VOA) – to help doctors identify patients at risk of having an opioid overdose. According to company officials, VOA predicts the likelihood of an overdose with nearly 90 percent accuracy.

“The apparent accuracy is extraordinary and if broadly implemented should save lives,” said Webster. “I hope the CDC, CMS (Centers for Medicare and Medicaid Services) and policymakers study this paper before they suggest further changes that could cause more suffering and harm for people in pain.”

According to the CDC, over 15,000 overdose deaths in U.S. in 2015 were linked to prescription opioids, although there’s no way of knowing whether the drugs were taken medically or recreationally. Another 18,000 overdoses involved heroin or illicit fentanyl, which have replaced painkillers as the driving force behind the nation’s opioid epidemic.