Are Opioids Effective in the Treatment of Chronic Low Back Pain?

April 17, 2019


By Anna Hirsch

Peer Reviewed

The use of opioid medications for chronic low back pain, or for any chronic non-cancer pain complaint, is still a source of controversy in the medical community, with a large divide between the recommendations of professional societies and actual physician prescribing data. In the last four years, the American Association of Neurology,1 the Centers for Disease Control,2 and the American College of Physicians3 have all issued guidelines urging caution with the use of opioids for chronic back pain, specifically emphasizing the poor-to-moderate quality of the evidence demonstrating benefit from this therapeutic modality. All three organizations reinforce that opioids should only be used after failure of other non-opioid and non-pharmacologic treatment options and recommend that if physicians choose to prescribe opioids, they should use the lowest possible doses with frequent reassessment of the risks and benefits of treatment for their patients. Yet, in stark contrast to these recommendations, an analysis of data from the Medical Expenditure Panel Survey estimates that 12.6% of patients with back pain not caused by an acute injury received opioid prescriptions, and that rate was significantly higher (26.2%) in patients with a positive PHQ-2 screen for depression at the time of prescription.4 Further support for these figures comes from the National Health and Nutritional Examination Survey, in which 14.5% of patients with chronic low back pain reported long-term opioid use.5

Previously, the best evidence to support the use of opioids for chronic low back pain–and the evidence on which the three organizations based their recommendations–came from a few dozen short-term randomized controlled trials comparing the use of opioids against placebo for the treatment of back pain. A meta-analysis published in 2016 in JAMA Internal Medicine analyzed the results from 13 of these trials, which included 3419 subjects with chronic pain and followed them for a duration of three months or less.6  They found moderate-quality evidence that opioids reduced subjects’ pain scores throughout the study period in a dose-dependent fashion, but without any clinically important pain relief within the guideline-recommended 40-240 mg of morphine equivalents per day. There was also no clinically significant impact on disability measures in any of these trials, nor did treatment or follow-up extend past three months. Furthermore, half of the 13 trials had a study withdrawal rate >50%, mainly due to lack of efficacy or adverse events (most commonly headache, somnolence, dizziness, constipation, nausea). Overall, the generalizability of this evidence was limited by small trial sizes and short follow-up periods, leading to a lack of data about the serious complications and adverse events associated with long-term opioid use, which include bowel obstruction, sleep apnea, bone fractures, endocrine dysfunction, myocardial infarction, hyperalgesia, and addiction-related sequelae.7-9

Within the last six months, the first long-term trial assessing the use of opioids for chronic back or osteoarthritis pain was published. The Strategies for Prescribing Analgesics Comparative Effectiveness (SPACE) trial randomized 240 patients from VA primary care clinics to receive either opioid or non-opioid therapy (starting with acetaminophen or NSAIDs) in an open-label,  treat-to-target strategy.10 Patients were assessed based on their self-reported pain-related function, pain intensity, and medication-related symptoms throughout the study period. After 12 months, there was no significant difference in pain-related function between the two groups, pain intensity was significantly better in the non-opioid group, and the incidence of adverse medication-related symptoms was significantly higher in the opioid group. Major strengths of this trial include a study withdrawal rate of only 2.5%, a duration four times as long as other published RCTs, and comparison to standard-of-care non-opioid medical therapy instead of placebo, which better approximates actual clinical practice. Notable weaknesses include lack of blinding, dependence on self-reported measures for the primary and secondary outcomes, and lack of generalizability of the study population, which included approximately 88% Caucasian males with a higher-than-average prevalence of comorbid mental health conditions.

Currently, the SPACE trial stands alone in a sea of low-quality evidence attempting to answer this controversial and heavily politicized question: are opioids ever indicated for the treatment of chronic pain conditions? It remains to be seen exactly how this study will influence the rates and patterns of opioid prescribing for low back pain in the coming years. It is possible that, as more evidence accumulates about the long-term risks of opioid therapy and the superiority or non-inferiority of non-opioid treatment modalities, the scales may tip away from the use of opioids for the treatment of chronic low back pain, and the practice will be abandoned altogether.

By Anna Hirsch is a 2nd year medical student at NYU School of Medicine

Reviewed by Richard Greene, MD, department of medicine, NYU Langone Health

Image courtesy of Injurymap.com through Wikimedia Commons: https://www.injurymap.com/free-human-anatomy-illustrations

References 

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