Fibromyalgia remains one of the most challenging conditions for insurers to assess due to its complex, often invisible, symptoms and historically limited scientific understanding.

Understanding the scale and distribution of fibromyalgia is crucial for contextualising claims. It is estimated to affect 2-4% of the global population, with some sources suggesting up to 6%. In the UK, that equates to approximately two to three million people being affected at any one time. There is also a gender disparity, with 70–80% of diagnosed cases found in women. More often than not, there is a delay in diagnosis, which can impact the patient’s mental health.

However, recent large-scale genetic studies are beginning to shed light on its biological background, offering new perspectives that could influence how claims are evaluated.

Two major genome-wide association studies (led by Michael Wainberg at Mount Sinai Hospital in Toronto and Joel Gelernter at Yale Medical School), involving millions of participants, have identified genetic variants linked to fibromyalgia. These findings reinforce the hypothesis that fibromyalgia is primarily a disorder of the central nervous system, with many implicated genes playing roles in neuronal function and pain processing.

Variants found in genes like huntingtin (associated with Huntington’s disease) suggest that fibromyalgia may involve subtle neurological changes, though not necessarily neurodegeneration.

Some variants are also linked to PTSD, indicating overlapping pathways in pain perception and emotional regulation.

Furthermore, separate research continues to support an autoimmune hypothesis, with studies showing that antibodies from fibromyalgia patients can induce pain sensitivity in mice.

While these studies are yet to be peer-reviewed, these findings have several implications for the claims arena:

• Validation of diagnosis: The identification of genetic markers and neurological involvement lends credibility to fibromyalgia as a legitimate medical condition, countering outdated perceptions of it being “made up” or exaggerated.
• Causation complexities: Fibromyalgia is likely multi-causal, involving genetic predisposition, immune responses, and environmental triggers. This complexity means that symptom variability among claimants is expected and medically plausible.
• Treatment limitations: Current interventions - exercise, antidepressants, and cognitive therapies - are reported to have mixed success. The lack of definitive treatment should not be interpreted as a lack of severity or legitimacy of the condition.
• Functional impact: Symptoms such as hypersensitivity to stimuli, chronic pain, and fatigue can impair daily functioning even in the absence of visible pathology.
• Need for nuanced evaluation: Given the evolving science, claims involving fibromyalgia should be approached with a balanced understanding of both the medical evidence and the claimant’s lived experience. Objective measures may be limited, but subjective reports are increasingly supported by biological research.

Conclusion

As research progresses, fibromyalgia is transitioning from a “mystery illness” to a condition with identifiable biological roots. Claims handlers and solicitors alike should stay informed of these developments to ensure fair, evidence-based evaluations. Recognising fibromyalgia’s legitimacy and complexity is essential for ethical and accurate claims handling.

Tim Large leads Clyde & Co's Chronic Pain Subject Matter Group.