Chronic pain is generally characterised by pain that persists for a period of three months or more. It can occur as a symptom or comorbidity of other conditions; however, the International Classification of Diseases 11th Revision of the World Health Organisation in collaboration with the International Association for the Study of Pain (IASP) recognises some forms as chronic pain, including fibromyalgia, as a distinct health condition and not a symptom of another disease. Fibromyalgia is believed to affect around 2.7% of the general population, with some figures suggesting that prevalence may be higher in the UK. The condition is more common among women than men and more commonly affects people over the age of 50, with lower socioeconomic status, and those who live in rural areas.
The diagnosis of fibromyalgia is based on a clinical evaluation, whereas the validity of biomarkers is limited. In 2018, new diagnosis criteria were proposed for fibromyalgia. In Quebec, Canada, the Ministry of Health defined the diagnosis of fibromyalgia according to three characteristics. Firstly, the presence of pain in 9 possible sites. In addition, the multisite pain must be accompanied by other manifestations (i.e., fatigue or sleep problems) and must have been present for at least 3 months. Finally, a full assessment must be performed to exclude the possibility of any other differential diagnoses.
Treatment of Fibromyalgia
Treatment of fibromyalgia should be multimodal, including a combination of pharmacological, physical, and psychosocial approaches. Physical approaches, such as exercise, Pilates, and aquatic exercise, and psychosocial approaches including psychotherapy, should usually be combined with pharmacological treatment aimed at reducing pain and comorbidities such as depression, anxiety, and fatigue.
According to the Quebec algorithm for the management of fibromyalgia and the Canadian guidelines for the diagnosis and management of fibromyalgia syndrome, the first-line pharmacological treatment of fibromyalgia includes antidepressants and anticonvulsants. Opioids (except for tramadol), non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol are not recommended considering their lack of efficacy for this type of disorder. The Canadian guidelines suggest that a trial of prescribed cannabinoid-based medications may be initiated, particularly in cases where patients have severe sleep problems.
While current clinical practice guidelines are built on solid evidence from randomised control trials and meta-analyses, medication prescription and use in the clinical context can be quite different – especially in the context of chronic pain management which is often characterised by off-label prescribing and use, multimorbidity, and polypharmacy. A recent study aimed to “establish a profile of pain medications used by people living with fibromyalgia” and to “compare this profile to the Canadian clinical practice guideline for the diagnosis and management of fibromyalgia syndrome.”
Design and Methods of the Study
From February to June 2022, 141 adults who were living with chronic pain and were using medications to manage their pain in Canada (recruited from participants of the ChrOnic Pain trEatment (COPE) Cohort) were invited to complete a structured telephone interview about medications used. A total of 63 participants self-reported having received a diagnosis of fibromyalgia and were included in the final patient sample.
A three-part questionnaire was conducted during a telephone computer-assisted interview. The first part of the questionnaire focused on sociodemographic questions. The second part consisted of more specific questions about pain (i.e., duration of pain in days/months or years, diagnoses other than fibromyalgia, access to a specialised pain clinic, and one open question on the use of physical and psychosocial treatments). The third part asked about different pharmacological treatments used currently for chronic pain management. The Medication Quantification Scale 4.0 was used, allowing participants to describe medications currently used, the number of medications used, and the perceived risk of use.
Results of the Study
Of the 63 individuals who took part in this study, almost half (44.4%) reported another chronic pain diagnosis in addition to fibromyalgia, with 15.9% of people having more than two pain diagnoses. The most common additional diagnosis was osteoarthritis (20.6%). Polypharmacy (current use of five or more medications) was found for more than half of the sample (52.4%) while excessive polypharmacy (current use of 10 or more medications) was reported by 9.6% of participants. This included analgesics and co-analgesics, over-the-counter medications, medical cannabis, prescribed cannabinoids, and “as needed” medications.
The five medication subclasses most frequently used were paracetamol (73.0%), oral NSAIDs (60.3%), serotonin and noradrenaline reuptake inhibitors (55.6%), calcium channel blockers anticonvulsants – gabapentinoids (36.5%), and medical cannabis (34.9%).
More than 85% of the participants used physical and/or psychosocial treatments to relieve their pain at the time of the interview. This included physical exercise (31.5%), meditation (25.9%), massage therapy (25.9%), heat and cold (24.1%) and physiotherapy (24.1%).
Comparisons with fibromyalgia clinical practice guidelines and reports
In Canada, two drugs are authorised by Health Canada for the treatment of fibromyalgia: duloxetine and pregabalin. Among the participants in this study, 60.3% reported using at least one of the two recommended drugs. Almost a third (31.8%) were using both medication subclasses. It is possible that participants who did not report current use of these medications had tried them in the past, but they were not tolerated or were not effective at the prescribed dosage.
Prescribed cannabinoids (e.g., nabilone) and medical cannabis use were reported by 34.9% of participants despite a paucity of evidence in this population. Half of participants reported using NSAIDs and more than a third reported using opioids despite the established lack of effectiveness for fibromyalgia. Such differences between recommendations and medication use could be explained by gaps between the available evidence and what really happens in clinical practice. The data collected in this study highlight that medication subclasses that patients considered most at risk of adverse effects were used least.
These findings demonstrate the discordance between evidence-based recommendations and medication use which highlights the complexity of pharmacological treatment of fibromyalgia and the need to better equip clinicians and patients. The authors note that “possible ways of reducing the gap between the results of scientific studies and clinical practice is to frequently update guidelines with active strategies to implement recommendations along with medical education.” Furthermore, they suggest that, from a patient empowerment and deprescription perspective, self-management strategies should be promoted.