Opioids No Better for Acute Neck and Back Pain Than Non-Opioid Treatment

No significant difference was found in pain scores for opioid analgesics versus placebo for acute lower back or neck pain, the OPAL clinical trial found.

At 6 weeks, mean pain scores on a 10-point scale were 2.78 in the opioid group versus 2.25 in the placebo group (P=0.051), Chung-Wei Christine Lin, PhD, of the University of Sydney in Australia, and co-authors reported in The Lancet.

Both groups received guideline-recommended care, including non-steroidal anti-inflammatory drugs (NSAIDs). Adverse events were similar in the two groups (35% in the opioid group and 30% in the placebo group, P=0.30).

"This trial has clearly shown there is no benefit to prescribing a short course of an opioid medicine for pain management in people with acute back or neck pain, and in fact, it could cause harm in the long-term even with only a short course of treatment," co-author Andrew McLachlan, PhD, also from the University of Sydney, wrote in an email to MedPage Today.

As many as two-thirds of Australians are prescribed opioids when they present with lower back and neck pain, despite clinical guidelines recommending them as a last resort, the authors noted. In the U.S., a study using data from 2013-2016 found that 32.3% of patients visiting the emergency department for acute lower back pain were prescribed opioids. In 2022, the CDC changed its opioid prescribing guidelines for acute, subacute, and chronic pain.

"The OPAL trial is a single trial, but it raises serious questions about the use of opioid therapy for acute low back and neck pain," wrote Mark Sullivan, MD, PhD, and Jane Ballantyne, MD, of the University of Washington in Seattle, in an invited commentary.

One explanation for the study's findings could revolve around the definition of chronic versus acute pain, they suggested. Participants were required to have only 1 month pain-free prior to their current pain episode, they noted.

"If many of these participants had recurrent pain, this might account for the non-response to opioid therapy," Sullivan and Ballantyne wrote. "Low back pain has been reported to transform over a year from a more sensory and nociceptive pain problem to one that is more emotional and nociplastic" and these nociplastic syndromes, which "can include chronic low back pain, are defined by altered nociceptive processing and are known to respond poorly to opioid therapy."

The editorialists also pointed out that, based on the Current Opioid Misuse Measure, 20% of the opioid group and 10% of the placebo group were at risk of opioid misuse at the 1-year mark. "These cognitive and affective changes could persist beyond the period of opioid use," they noted.

OPAL ran at 157 primary care or emergency department sites in Sydney from 2016 to 2022. It included 347 adult participants presenting with a primary complaint of lower back pain or neck pain, whose current episode had been 12 weeks or less, and who had spent at least 1 month prior to the episode pain-free in these areas.

The opioid group started an oral dose of 5 mg oxycodone and 2.5 mg naloxone twice a day, gradually titrated up to 10 mg oxycodone twice a day, depending on the patient, for a maximum of 6 weeks. Both groups received guideline-recommended care including reassurance of a positive prognosis, advice to stay active, and treatment including non-opioid analgesics.

More than half of participants in each group used concomitant medications for back and neck pain. "Over the 52 weeks of the trial, 37% of participants reported taking NSAIDs in our opioid treatment group and 42% in the placebo group," a difference that was not statistically significant, McLachlan said.

Overall, 49% of participants were female and mean age was 44.7, with 174 randomized to the opioid group and 173 to the placebo group. A total of 33 and 15 patients, respectively, were lost to follow-up or withdrew from the study by week 6. Follow-up was at 2, 4, 6, 12, 26, and 52 weeks.

The primary outcome was measured with the Brief Pain Inventory at 6 weeks. Secondary outcomes included pain severity at other weeks, physical functioning in the back and neck, physical and mental quality of life, and global perceived effect. For secondary outcomes, there was either no difference or small effects favoring placebo. The most common adverse events were nausea and vomiting, constipation, headache, dizziness, and somnolence.

A limitation of the study was that 25% of the data were missing at the primary timepoint, which may have introduced bias, the researchers noted. Only 58% of participants reported their compliance to the medication regimen (taking 80% or more of the medication), and of these, just more than half were compliant. In addition, little data were collected about the kind of guideline-recommended care provided.

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