Unexpected findings
The new results were somewhat unexpected, said Mr. Wewege.
“When we set out to do this review, we envisioned the evidence would be a lot more comprehensive. We didn’t think it would be so disconnected and there would be so few trials looking at the different comparisons that would lead us to have low confidence in most of the findings.”
Various factors contributed to this low confidence, he said. One was the risk of bias – about 90% of trials had some concerns or high risk of bias. Another factor was the heterogeneity in effect estimates.
Most of the evidence is based on studies comparing different analgesics to placebo, Mr. Wewege noted. The lack of head-to-head drug comparisons is because “the easiest way to get a drug approved is just to demonstrate it’s better than placebo,” he said.
In addition to these new findings, clinicians should consider a medication’s availability, their own expertise, and patient preferences when selecting an analgesic, said Mr. Wewege. He noted most patients with acute low back pain get better within a few weeks without any intervention.
“Patients should be reassured that things will heal naturally and that they are not going to be in pain forever,” he said.
Determining optimal treatment is key
Chris Gilligan, MD, associate chief medical officer, Brigham and Women’s Hospital, and associate professor of anesthesia, Harvard Medical School, both in Boston, said determining which medications are optimal is “key,” as acute low back pain is very common and analgesics are used frequently.
The new review does provide information on which medications have the strongest evidence for pain reduction, said Dr. Gilligan. “On the one hand, it directionally points you towards certain medications, and even certain classes of medication, for comparative effectiveness.”
However, he said, the confidence for this effectiveness is low or very low, “so I wouldn’t overweight it.”
The data on adverse effects, where the confidence is mostly moderate to low, might have more of an influence on prescribing, he said.
“For example, there’s some indication tramadol may be more closely associated with adverse events in patients with acute low back pain and that would add to our caution about using tramadol; it’s not that we would never use it, but [we]would take that into account.”
Dr. Gilligan agrees clinicians should be cautious about prescribing analgesics for low back pain. One reason for being conservative in terms of treatments, he noted, is that “acute low back pain has a very favorable natural history.”
While clinical practice guidelines recommend nonpharmacologic therapies as first- and second-line treatment for acute, nonspecific low back pain, Dr. Gilligan noted that as with drugs, evidence for nondrug therapies also has low or very low confidence.
The study received funding from a 2020 Exercise Physiology Research (Consumables) Grant from the University of New South Wales, which was used to obtain translations of studies published in languages other than English.
Mr. Wewege was supported by a Postgraduate Scholarship from the National Health and Medical Research Council of Australia, a School of Medical Sciences Top-Up Scholarship from the University of New South Wales, and a PhD Supplementary Scholarship from Neuroscience Research Australia. Dr. Gilligan reports that he conducts clinical trials with companies and groups, including the National Institutes of Health related to medications, devices, and procedures for pain.
A version of this article first appeared on Medscape.com.