HealthDay News — The effectiveness and safety of long-term opioid therapy for treatment of chronic low back pain remains unproven, findings from a meta-analysis suggest.
“The literature does not support that opioids are more effective than other groups of analgesics for [low back pain] such as anti-inflammatory drugs or antidepressants,” Luis Enrique Chaparro, MD, from Hospital Pablo Tobon Uribe in Medellin, Columbia, and colleagues reported in Spine.
The meta-analysis was an update to an existing 2007 Cochrane Review with data from 12 new randomized controlled trials conducted through October 2012.
Overall, 15 trials with 5,540 participants met inclusion criteria. The studies assessed the use of noninjectable opioids in chronic low back pain for at least four weeks versus placebo or other treatments. However, comparisons of different opioids were excluded.
Although not associated with long-term effectiveness, there is evidence that opioid treatment may provide short-term relief for chronic low back pain compared with placebo, the researchers found.
In five studies that assessed tramadol (N=1,378), there was “low quality evidence” indicating the medication improved pain scores better than placebo (standard mean deviation −0.55; 95% CI: −0.66 to −0.44) and “moderate quality evidence” of benefit on functional outcomes (SMD −0.18; 95% CI: −0.29 to −0.07).
Two studies involving 653 participants assessed transdermal buprenorphine. The researchers found “very low-quality evidence” that transdermal buprenorphine is better than placebo in improving pain (SMD, −2.47; 95% CI, −2.69 to −2.25); however, there was no difference in functional outcomes among patients assigned to the medication versus placebo.
Six studies involving 1,887 patients assessed strong opioids including morphine, hydromorphone, oxycodone, oxymorphone and tapentadol. The researchers found “moderate-quality evidence” that opioids were better for improving pain (SMD, −0.43; 95% CI: −0.52 to −0.33) and function (SMD, −0.26; 95% CI: −0.37 to −0.15) than placebo.
There was no difference between opioids and antidepressants for pain or function in two trials (272 participants). There were no reports of serious adverse effects, risks (addiction or overdose) or complications (sleep apnea, opioid-induced hyperalgesia, hypogonadism).
The overall quality of the trials included in the analysis was low to moderate. Study limitations include high dropout rates (>20%), short study duration (less than 15 weeks) and limited interpretability of functional improvement.
The researchers called for more high-quality randomized controlled trials to assess the long-term risks and benefits of opioid therapy for chronic low back pain.
Disclosures: Relevant financial activities outside the submitted work were reported: board membership, consultancy, honoraria, employment and royalties.