Opioids and Fibromyalgia

Although chronic opioid therapy (COT) can be effective for many forms of chronic noncancer pain, there is little evidence that supports its use in the treatment of fibromyalgia. The authors of “Clinical Guidelines for the Use of Chronic Opioid Therapy in Chronic Noncancer Pain,” published in 2009 by the American Pain Society (http://bit.ly/lWFtTQ), wrote that “Although neuropathic and non-neuropathic pain conditions appear in general to respond similarly to COT, evidence that demonstrates the efficacy of COT for conditions with strong psychosocial contributors such as some types of chronic low back pain, daily headache, and fibromyalgia is sparse. There is insufficient evidence to recommend use of an intravenous opioid trial to predict likelihood of benefit from COT.”

Despite the dearth of high-quality evidence supporting the use of opioids (or at least the use of strong opioids) in the management of fibromyalgia pain, several studies have shown that these medications may be widely used in this patient population. The authors of “Opioid Use, Misuse, and Abuse in Patients Labeled as Fibromyalgia,” published in the American Journal of Medicine (http://bit.ly/nstDVx), conducted a chart review of 457 patients at a tertiary pain clinic who had received a diagnosis of fibromyalgia. The authors reported that, even though there is “limited information about opioid treatment in fibromyalgia, with all current guidelines discouraging opioid use,” they found that the records showed that nearly one-third of the patients had been prescribed opioids for their condition (nearly two-thirds of whom had received “strong opioids,” according to the authors).

Similarly, the authors of “The Use of Opioids in Fibromyalgia,” published in the International Journal of Rheumatic Diseases (http://bit.ly/qRIQZ1), also found that opioid medications are frequently prescribed to patients with fibromyalgia. They cited one study (http://bit.ly/pdIrew) that showed that up to 14% of patients with fibromyalgia who receive care at American academic medical centers are treated with opioid medications. Another study cited by the authors looked at records in a health insurance database and found that 37% of fibromyalgia patients received short-acting opioids and 8% received long-acting opioids. Given the lack of randomized controlled trials addressing the short- or long-term use of opioids in the treatment of fibromyalgia, plus the adverse effects associated with the use of opioids in patients with fibromyalgia—the authors mention constipation (“particularly unwanted in patients in whom irritable bowel syndrome often co-exists”), dose-dependent mental clouding and sedation that “may worsen the cognitive dysfunction sometimes associated with fibromyalgia,” and opioid-induced hyperalgesia—the frequency with which these medications are prescribed to these patients is puzzling. However, the authors did note that there are several randomized controlled trials that support the use of tramadol in fibromyalgia. Still, they concluded that “Opioids can be particularly problematic” in patients with fibromyalgia,” and that, given the dearth of “concrete evidence of their benefit, and the availability of other medications which act on pathophysiological mechanisms, it is difficult to see a current role for opioids in a long-term [fibromyalgia] management program.”

Why Aren’t Opioids Effective in Fibromyalgia Patients?

The authors of “Decreased Central μ-Opioid Receptor Availability in Fibromyalgia” (http://bit.ly/pzFpJv) found decreased μ-opioid receptor (MOR) availability in patients with fibromyalgia (FM). This observation of “specific regional alterations in central opioid neurotransmission” in FM suggests that “These mechanisms, possibly as a consequence of persistent pain, are involved in the clinical presentation and even the perpetuation of symptoms in this illness. Furthermore, because these receptors are the target of opiate drugs, a profound reduction in the concentration or function of these receptors is consistent with a poor response of FM patients to this class of analgesics.”

A fibromyalgia treatment resource from the American College of Rheumatology (http://bit.ly/pHa2q3) notes that although tramadol can be used to treat fibromyalgia pain, “Other opioids are typically not recommended for the treatment of fibromyalgia unless patients are refractory (or resistant) to other therapies. This is not due to issues with dependence, but rather because anecdotal evidence suggests these drugs are not of great benefit to most people with fibromyalgia and in fact may cause greater pain sensitivity or persistence of chronic pain.”

These recommendations are supported by the “EULAR Evidence-based Recommendations for the Management of Fibromyalgia Syndrome” (http://bit.ly/a2pqvV), which recommended the use of the opioid analgesic tramadol for the management of pain in fibromyalgia, noted that other weak opioids “can be considered in the treatment of fibromyalgia,” and said that strong opioids are not recommended.

Ultimately, although the decision to use tramadol or other opioid medications to treat chronic pain associated with fibromyalgia should ideally be based on the best evidence available, treatment choices should be made on an individualized basis through a process of shared decision making by patients and their physicians. As efforts to raise awareness about best practices regarding pain care among non-specialist physicians who treat patients for fibromyalgia and other forms of chronic noncancer pain begin to produce results, we should see an increase in the use of evidencebased treatment choices.