Are opioids effective for low back pain?

09 Nov 07

The use of opioids in the long-term management of chronic low back pain seems to be increasing – but what are the benefits and risks of these drugs?

Methods

To try to determine the efficacy of opioids in adults with chronic low back pain, we electronically searched CENTRAL, CINAHL and PsycINFO to May 2006; MEDLINE and EMBASE to May 2007. We supplemented our search by reviewing relevant systematic reviews and identified trials.

We included randomised or quasi-randomised controlled trials assessing the use of opioids (as monotherapy or in combination with other therapies) for longer than four weeks, in adults with chronic LBP. Studies were included if they compared non-injectable opioids with other treatments. Comparisons between opioids were excluded.

Results were statistically pooled using RevMan 4.2. We reported on pain and function using standardised mean difference (SMD) with 95% confidence interval (95% CI) and on side-effects using absolute risk difference (RD) with 95% CI.

Main results

We included four trials. Three compared tramadol with placebo. Pooled results revealed that tramadol was more effective than placebo for pain relief, SMD 0.71 (95% CI 0.39 to 1.02), and improving function, SMD 0.17 (95% CI 0.04 to 0.30). The two most common side-effects of tramadol were headaches, RD 9% (95% CI 6% to 12%) and nausea, RD 3% (95% CI 0% to 6%).

One trial comparing opioids to another analgesic (naproxen) found opioids were statistically significant for relieving pain but not improving function. When re-calculated, the results were not statistically significant for either pain relief (SMD -0.58; 95% CI -1.42 to 0.26) or improving function (SMD -0.06; 95% CI -0.88 to 0.76).

Authors’ conclusions

Despite concerns about the use of opioids for long-term management of chronic low back pain, there are few high-quality trials assessing their efficacy. The trials in this review, although achieving high internal validity scores, were characterised by a lack of generality, inadequate description of study populations, poor intention-to-treat analysis and limited interpretation of functional improvement.

Based on our results, the benefits of opioids for the long-term management of chronic low back pain remain questionable. Further high-quality studies are needed.