What is the background to this research?
Fibromyalgia is a long-term condition associated with widespread pain, fatigue, sleep problems, and difficulties with concentration. However, people with fibromyalgia can experience very different levels of symptoms and distress, and the condition can affect their daily lives in different ways. Some people manage their symptoms relatively well, while others experience severe symptoms and substantial difficulties. Previous research has mainly grouped people according to their symptoms, with less attention to psychological well-being and social circumstances. Understanding these differences may help explain why people experience fibromyalgia differently and support more individualised approaches to care.
What did we seek to find out?
We aimed to identify distinct subgroups of people with fibromyalgia by considering a broad range of characteristics, including physical symptoms, psychological and behavioural factors, and social and demographic circumstances. We also examined which characteristics were most useful in distinguishing these subgroups and whether the identified groups remained consistent across different analyses.
What did we do?
We analysed data from 4,172 UK Biobank participants who met the 2016 American College of Rheumatology criteria for fibromyalgia. Participants were aged 40–69 years when originally recruited into the UK Biobank study. We used a statistical method called model-based clustering to group people according to similarities across 28 characteristics, covering social and demographic circumstances, clinical symptoms, and psychological and behavioural factors. We then compared the characteristics of the groups and examined which factors best distinguished them. We also repeated the analyses using different approaches to assess whether the groups were consistent and reliable.
What did we find?
We identified three distinct subgroups of people with fibromyalgia:
- The Resilient Majority (62.3%) had relatively low levels of physical symptoms and psychological distress. This group also reported lower levels of social isolation than the other groups.
- The Severe Phenotype (20.1%) experienced the greatest burden of pain, fatigue, sleep problems, and psychological distress. All individuals in this group reported feeling down on more than half of the days assessed. They were also more likely to report lower household income, lower educational attainment, and social isolation. They had higher rates of visits to general practitioners and mental health specialists.
- The Socially Vulnerable Minority (17.6%) was characterised by greater ethnic diversity, more rural residence, and indicators of social isolation. Around 35% of this group were from non-White European backgrounds, and 31% lived in rural areas. These characteristics were not observed in the other two groups in this study. We think this is the first time that a research study has specifically identified this group.
Psychological and behavioural factors, as well as social circumstances, were more useful for distinguishing the groups than clinical symptoms alone. In particular, how often people felt down, the population density of their home area, ethnicity, the frequency of visits from friends or family, and smoking status were among the strongest distinguishing factors. The three groups were also consistently identified across different analyses, supporting the reliability of the findings.
Why does this research matter?
These findings suggest that fibromyalgia cannot be fully understood by looking at pain and other physical symptoms alone. Psychological well-being, social connections, and living circumstances may also be important in understanding people's experiences and needs. Recognising these differences could help healthcare professionals consider more individualised approaches to care, including psychological support for people with greater distress and community-based support for those facing social or geographical barriers.
Who funded this study?
This research was partially funded by the BK21 FOUR program of the Graduate School, Kyung Hee University (GSX-20241663). The research was also conducted as part of the PACFiND programme, funded by Arthritis UK (previously Versus Arthritis) [Grant No. 21958]. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Where can I read more?
You can read the full research paper in the Journal of Pain at the following link:
https://doi.org/10.1016/j.jpain.2026.106469
Kim S-A, Morton L, Macfarlane GJ, Summers JA. Fibromyalgia Subgroups Identified Using Model-Based Clustering: Results from UK Biobank. The Journal of Pain (2026).