Opioids and fibromyalgia: frequency of use and factors associated with increased consumption in patients remitted to a tertiary care center.

Background: Opioids are not recommended for fibromyalgia.

Objective: To investigate the frequency of opioid use in a large cohort of fibromyalgia patients and to identify factors associated with opioid consumption.

Methods: A retrospective, observational study of a large fibromyalgia cohort in a tertiary care center. We assessed fibromyalgia severity, functional capacity, anxiety, depression, drugs consumption and the patient's impression of change. We compared strong opioid consumers (SOC) and non-SOC. Inferential statistical and logistic regression analysis were used to identify factors associated with opioid consumption, and ANOVA for repeated measurements.

Results: We found a prevalence of 9.2% of SOC (100 patients) among 1087 patients in the cohort. During the last four years there was a significant increase on the incidence of SOC up to 12.8% (p = 0.004). There were no differences in demographic variables between SOC and non-SOC. Clinical variables were significantly more severe in SOC, and they consumed more non-opioid drugs (p < 0.0001). Opioid consumption was independently associated with other non-opioid drugs (Odds ratio 1.25, CI: 1.13-1.38), but not with the fibromyalgia severity. At three months, 62% of the patients had opioid withdrawal. There were no statistical differences in the fibromyalgia severity at the initial evaluation, or the patient's impression of change compared with those patients who continued opioids. Coping strategies were better in those patients who withdrew opioids (p = 0.044).

Conclusions: We observed an increase in opioid prescriptions during the last four years. Opioid consumption was associated with concomitant use of non-opioid drugs, but it was not associated with fibromyalgia severity.