Background/Purpose: Opiate is not indicated in the treatment of fibromyalgia (FM). In fact, chronic use of opiate may even worsen the symptoms of fibromyalgia. There are reports in other pain conditions that long term use of opiate may even contribute to pain chronicity or the persistence of pain. Given the known medical complications from opiate (e.g., cognitive dysfunction) we hypothesized that the use of opiate may modify (or diminish) the effects of motivational interviewing (MI) treatment intervention on FM-relevant clinical outcomes.

Methods: This is a secondary data analysis of a 36-week randomized clinical trial to assess the efficacy of MI to promote physical activity among patients with FM. Participants were randomized to 1 of 2 treatment arms: 6 phone-based MI sessions (n=107) or an equal number of FM self-management instructions (attention control/AC, n=109). Subjects were evaluated at 4 time points: baseline, week 12 (post-intervention), week 24 and week 36. In the previous main outcome analyses†, MI was marginally superior (p=0.06) to AC in improving global FM symptom severity (as measured by Fibromyalgia Impact Questionnaire/FIQ total) from baseline to week 36. For the current analyses, the clinical outcomes were changes in FIQ total and SF36 physical function scores, from baseline to each follow-up visit. At study entry, subjects were categorized as opiate users vs. non-users.  Repeated measures ANOVA were used to assess treatment effects within each category.

Results: Approximately 5 subjects in MI and 8 subjects in the AC group had missing data; and therefore, were not included in the analyses.

Values are means (standard errors) Stratifying the data based on the use of anticonvulsant (i.e., pregabalin or gabapentin) at study entry, we found the reverse (data not shown).  Specifically, treatment benefits from MI were observed among anticonvulsant users, but not among non-users.

Conclusion: In contrast to opiate users, opiate non-users reported greater treatment benefits from MI. Based on our findings, a hypothesis can be made that opiate interferes with the (biological and/or psychological) mechanisms of psychoeducational treatment intervention for FM.  If replicated in future studies, opiate status may guide clinician on when best to offer MI for patients with FM. †Ang DC et al. Research to Encourage Exercise for Fibromyalgia. Clin J Pain 2013; 29:296-304