Opioid analgesics not linked to clinical improvement in chronic low back pain

1. In a meta-analysis of randomized controlled trials, opioid analgesics for chronic low back pain were associated with small, but clinically insignificant improvements in the short- and intermediate-term. This was true even at the highest doses used.

2. While there was marginal improvement in pain (per pain scores), there was no significant decrease in the rates of disabilities from low back pain, and there were greater adverse events amongst those who used opioids.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Chronic low back pain is a prevalent affliction and one of the most common causes of disability. Opioid analgesics are commonly prescribed for this, but concerns over the morbidity and mortality, and potential for abuse has prompted re-evaluation of this approach. The described study performed a systematic review and meta-analysis to evaluate the use of opioids in the management of chronic low-back pain.

The study, which consisted of twenty randomized controlled trials, found that, while opioid analgesics did improve pain scores in short- and intermediate-term follow up, these improvements were not clinically significant, even at the highest doses of opioids. Opioid use also was not associated with decreases in rates of disabilities from low back pain, and was associated with greater adverse events. While the study did utilize only randomized controlled trials, much of the evidence was downgraded in quality grade due to publication bias and the prevalence of industry funding.

Click to read the study, published today in JAMA Internal Medicine

Relevant Reading: Opioids Compared With Placebo or Other Treatments for Chronic Low Back Pain: An Update of the Cochrane Review

In-Depth [systematic review and meta-analysis]: This study evaluated 20 randomized controlled trials following systematic review regarding the efficacy of opioids in the management of chornic low back pain. Clinical benefit was based on pain scores from a scale of 0 to 100, with a 20-point reduction considered clinically significant.

Thirteen trials evaluated short-term effects of opioids on chronic low back pain with moderate-quality evidence of pain score improvements of -10.1 (95%CI -12.8 to -7.8), though 31.4% to 61.9% of patients withdrew from studies due to side effects or lack of response. From 6 trials there was high quality evidence of intermediate term benefit, -8.1 (95%CI -10.2 to -6.0). There was no statistically significant improvement in disability scores at short or intermediate term follow-up. In evaluation of dose response, there was 12.0 point improvement in pain scores per 1 log unit increase in morphine equivalent (p = 0.046). This corresponded to an estimated benefit of 6.7 points at 40 mg morphine equivalents per day and 16.1 points at 240 mg/day. However, even at the highest dose evaluated there was still no predicted clinically significant benefit.

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