To the Editor:
We appreciate the comments by Dr. Rothschild1 regarding the effect of opioids on adherence to an exercise program in patients with fibromyalgia (FM). Dr. Rothschild has suggested that sleep dysfunction due to opioids may be an important factor to explain poor adherence to exercise recommendations. The argument that opioids could accentuate the sleep disorder in persons with FM is correct. Whether sleep disorder per se, by whatever mechanism, is the unique reason to explain both the findings of the study by Kim and colleagues, as well as much of the symptomatology of FM, remains debatable2.
Sleep problem is a recognized core symptom of FM, and may manifest as difficulty falling asleep or staying asleep, frequent awakenings, or feeling unrefreshed after a period of sleep3. Poor sleep will contribute to fatigue and affect the ability to engage in a physical activity program. By adding another factor that affects sleep, such as opioid medication, the consequences may be compounded. Opioids are known to affect sleep in a number of ways, including reduction in rapid eye movement and slow wave sleep, as well as development of central sleep apnea4,5. We therefore entirely agree that disordered sleep may be an additive factor to poor function in patients with FM. However, other side effects of opioids such as drowsiness, fatigue, and depression must also be taken into account. Although never formally tested as a therapy for FM, with the exception of tramadol, opioids in patients with FM are associated with poorer health and psychosocial status and are not recommended by any current FM guidelines6,7. Nevertheless, opioids are currently used by almost a third of patients with FM in North America, and are perceived by patients to be among the most effective medications for treatment of FM2,8.
In view of the complexity of FM, compounded by an array of opioid-related adverse effects, it is too simplistic to invoke opioid-induced sleep disturbance as the principle reason for nonadherence to an exercise program. Regardless of the exact or predominant mechanism involved in nonparticipation, we believe that the message of adverse events related to medication use in patients with FM is loud and clear. The effect of medications on symptoms of FM cannot be overestimated, with the knowledge that opioids in particular may contribute to many symptoms prevalent in patients with FM. Any drug treatment used to manage FM must be regularly evaluated for continued efficacy and side effects, with careful attention to ensure that medication side effects do not outweigh the therapeutic benefit.