The majority of fibromyalgia patients are taking medications unsupported by evidence for their condition, with over a third using opioids, an Australian study suggests.

Researchers say the finding highlights how most fibromyalgia patients struggle to find effective or tolerable medications, despite the widespread use of evidence-based treatments such as amitriptyline and duloxetine.

The chart review included 474 patients who had attended the Monash Fibromyalgia Clinic in Melbourne between January 2019 and June 2022, 108 of whom also completed an anonymous questionnaire to assess current therapeutic use at the close of that period.

Some 48.5% of chart review patients and 58.3% of questionnaire participants reported using at least one evidence-based medication, most frequently low-dose amitriptyline, duloxetine or pregabalin.

Usage rates of the three, which ranged from 30%-21% per the questionnaire, reflected the fact these were the guideline-recommended medications with the strongest supporting evidence, the researchers reported in Internal Medicine Journal (link here).

It also aligned with the clinic’s prescribing practices and medication availability in Australia, although there were currently no drugs specifically subsidised on the PBS for fibromyalgia, they noted.

Interestingly, these three medications were also the most commonly-previously trialled by chart review patients, with past usage rates eclipsing current usage rates, reflecting the limits of variable tolerability and efficacy, according to the authors.

Perhaps more troubling was the very high rate of medications not recommended in the guidelines, with 60% using paracetamol and 48% NSAIDs, per the questionnaire.

Of some concern, much of this use had not appeared in the patients’ charts, indicating these records “may not be current or complete even in a specialist clinic”, the researchers added.

Opioid use

And given the clinic did not prescribe opioids and encouraged their cessation, the fact that 37% of chart review patients were currently on an opioid was another issue, likely reflecting prescriptions obtained elsewhere.

In addition, fewer patients reported past than current opioid use, suggesting they were continuing long term.

“With 5.7% of chart review patients taking opioids alone for their fibromyalgia, there is room to educate and optimise management strategies in this patient group,” the authors said.

A quarter of chart review patients and 11% of questionnaire respondents who reported current opioid use disclosed taking multiple opioids, they added.

The study also indicated that cannabinoid use was increasing in the patient group, with 6% of those in the chart review and 15% of questionnaire recipients reporting currently taking it in some form.

Notably, only half sourced it through a prescription, while 88% of those using cannabinoids reported concurrent opioid use.

“This combination heightens the risk of other complications and has been associated with increased anxiety and depression, two common fibromyalgia comorbidities,” the researchers noted.

They concluded: “Patients do not always disclose all of their management strategies and use of pharmacologically active substances, and chart records may not be current or complete even in a specialist clinic.”

“Awareness of this can foster a safer pharmacotherapeutic environment with more insightful prescribing habits, reminding clinicians  to  inquire  about  all  possible  management strategies.”