Little Evidence Supports Opioid Use for Chronic Pain

A new study reveals that there is paltry evidence for the long-term safety and efficacy of opioids in the treatment of chronic pain.

Researchers at the Oregon Health & Science University (OHSU; Portland, USA) and the University of Washington (Seattle, USA) searched MEDLINE, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, PsycINFO, and other sources for randomized trials and observational studies that evaluated the effectiveness and harms of opioid therapy in adults with chronic pain who were prescribed long-term (over three months) therapy.

The results showed that no study of opioid therapy evaluated long-term outcomes related to pain, function, quality of life, opioid abuse, or addiction. Conversely, observational studies suggested that opioid therapy for chronic pain is in fact associated with increased risk for overdose, opioid abuse, fractures, myocardial infarction (MI), and markers of sexual dysfunction, although there are few studies for each of these outcomes; for some harms, higher doses were associated with increased risk. The study was published on January 13, 2015, in Annals of Internal Medicine.

“The lack of scientific evidence on effectiveness and harms of long-term opioid therapy for chronic pain is clear and is in striking contrast to its widespread use for this condition and the large increase in prescription opioid-related overdoses,” concluded lead author Roger Chou, MD, of OHSU, and colleagues. “Evidence is insufficient to determine the effectiveness of long-term opioid therapy for improving chronic pain and function. Most randomized, controlled trials of opioids for chronic pain were shorter than 6 weeks, and nearly all ran for no longer than 16 weeks.”

Prescriptions of opioid medications for chronic pain have increased dramatically, a trend that has been accompanied by greatly increased levels of opioid overdose, abuse, addiction, and diversion. When compared with placebo, opioid therapy has been found to be associated with alleviation of pain in the short term, but most opioid trials do not extend beyond six weeks and are of limited relevance to long-term opioid use.

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Oregon Health & Science University
University of Washington