According to a study in the September issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS), the risk of continuing to use strong pain-relieving drugs many months after surgery increases with non-pain related factors, such as previous use of pain medications, symptoms of depression, and high perceived risk of addiction.

Dr. Ian Carroll of Stanford University and lead author, said: “Each of these factors was a better predictor of prolonged opioid use than postoperative pain duration or severity.”

In order to recognize preoperative factors that predict continued use of opioid drugs long after an operation, the experts analyzed factors associated with long-term use of strong pain medications in 109 patients who were undergoing various types of operation, such as chest surgery, breast cancer surgery, or joint replacement.

Patients were evaluated before undergoing surgery for factors that the researchers believed could potentially influence the use of pain medications.

After the procedure finished, each patient underwent regular assessment of their use of opioid medications, such as morphine and other associated drugs.

Five months after operation, 6% of the subjects still had a doctor’s order to take opioid drugs.

After adjusting for other factors, scientists discovered 3 factors that were independently related to long-term opioid use:

  • Patients who were using opioids for pain relief before their procedure, prescribed or not, had a 73% increased chance of using the drugs at follow-up.
  • Those who rated themselves at increased risk of developing an addiction had a higher chance of long-term drug use. The risk was increased by 53% for each 1-point increase on a 4-point scale of perceived addiction risk.
  • Those with symptoms of depression had a 42% increased risk for every 10 points on a standard scale (the Beck Depression Inventory).

These 3 factors were significant no matter which type of surgery the patient underwent, and were also better predictors of long-term opioid drug use than the severity of pain or how long the pain lasted after operation.

The authors explained:

“As patients recover from surgery, they face an ongoing choice either to continue taking prescribed opioids or to stop opioids and undertake non-opioid pain treatment.”

There has been little research on the factors that affect ongoing use of strong pain medications after surgery. Opioid drug use in patients with chronic pain is more associated with psychological distress and substance abuse than to the intensity of the pain.

According to the team, long-term opioid use is also linked to non-pain-related factors in patients having an operation. They discovered that there would be 1.1 million new users each year, if there 6% rate of long-term drug use applied to the average 17.6 million people undergoing procedures each year.

There has been a rapid increase in the use of prescription opioid drugs over the years, for both doctor prescribed pain treatment and recreational use.

Some of the long-term opioid use in this research could have been legitimate, Dr. Carroll and colleagues pointed out. However, the findings raise concerns about the “disconnect” between the reason these drugs are prescribed and the non-pain related risk factors.

They concluded that more studies need to be conducted in order to clarify the relationship between opioid abuse and addiction and the three risk factors found in this study.

Written by Sarah Glynn