Studies Find Long Term Use of Opioids Ineffective
/By Pat Anson
Results from two new studies suggest that opioid pain medication is useful for treating short-term acute pain, but the benefits decline when opioids are taken long term.
In the first study, researchers at the University of Alberta conducted a systematic review of 27 randomized controlled trials of opioids used in the treatment of osteoarthritis or chronic low back pain. Trials were excluded from the review if participants had back pain from surgery, cancer, lumbar spinal stenosis, radiculopathy, sciatica, or rheumatic conditions.
The study findings, recently published in the British Journal of General Practice, show that opioids work well in the first four weeks of acute pain, but provide little or no benefit if used for longer periods. If taken for more than 12 weeks, researchers say opioids may increase a patient's sensitivity to pain – a controversial theory known as hyperalgesia.
"If someone breaks a limb, has surgery or a dental problem, where you anticipate the problem is going to resolve in a relatively short time, it's probably OK to give an opioid for that," says principal investigator Scott Garrison, MD, Professor of Family Medicine at the University of Alberta.
"Opioids still have a role in managing acute pain. But if the patient has a condition where this pain is going to be chronic, I think you should reconsider whether you should be offering an opioid, because you may only be giving very short-term pain relief with the possibility of worse pain in the long run, not to mention other potential problems from the opioids."
Garrison and his colleagues made a point of excluding studies from their review if they used a trial design known as "enriched enrollment randomized withdrawal" or EERW. Critics of the EERW method claim it skews data in favor of long-term opioid use.
While the researchers acknowledge that opioids provide clinically meaningful pain relief for acute pain, they discourage patients from ever taking them. In his own family practice, Garrison says patients refuse to take opioids once he warns them about potential side effects.
"It's very hard to get people off opioids once they have started them, but when patients are given this information about potential harms, they don't want the drug," Garrison said. "Absolutely every patient who is told this up front ends up not taking the opioid. It's so hard to stop, but it's so easy not to start if people are fully informed."
No Changes in Brain Anatomy
The second study also concluded that long-term opioid use does not reduce pain or improve physical function in people with chronic back pain. But the research team at Northwestern University found that long-term opioid use does not cause lasting harm to the brain.
The study compared 70 patients who took opioids for chronic back pain to 70 similar patients who were opioid naive. On average, the opioid group took low to moderate doses for 7.8 years.
The study findings, published in the journal Brain, show the opioid and non-opioid groups reported nearly identical levels of pain, about 5.4 on a zero-to-10 pain scale. The opioid group had slightly worse results for physical function and mental health.
When MRI images were taken of both groups, researchers found little evidence that years of taking opioids altered the brain's anatomy.
"The psychological and brain properties of the participants on long-term prescription opiates were essentially intact," said senior study author A. Vania Apkarian, PhD, director of the Center for Translational Pain Research at Northwestern University Feinberg School of Medicine.
"That's good news because there's this fear nowadays that as soon as you start ingesting opiates, your brain is going to go crazy, and it doesn't," Apkarian said. "But the bad news is that we saw no sign that their pain had gotten any better by using this drug for so many years."
This is believed to be the first study to look at long-term opioid consumption and its effect on the brain. While the MRIs showed no changes in brain anatomy, the images did find differences in the opioid group in how brain regions function and communicate with each other.
That was particularly true in parts of the brain involved in reward and motivation, suggesting that long-term opioid use may encourage drug-seeking behavior.
Previous studies of long-term opioid use found that only a small percentage of patients become addicted or abuse their medication and the risk of long-term use is low.
A large study in Australia that followed over 1,500 patients on opioids for five years found that “problematic opioid use” was infrequent. Less than 10% of patients asked for higher doses or for a prescription to be renewed early. By the end of the study, patients were more likely to have stopped taking opioids (20%) than to be diagnosed with opioid dependence (8%).
