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INCHEON, South Korea — People with osteoarthritis are more likely to be diagnosed with other pain-related comorbidities such as fibromyalgia, chronic fatigue syndrome (CFS), gout, and irritable bowel syndrome and psychological comorbidities such as depression, according to observational data presented at the World Congress on Osteoarthritis (OARSI) 2025 Annual Meeting.

The study also found that all these five conditions were themselves associated with an increased risk for incident osteoarthritis, and in the case of fibromyalgia, there may be a causal association.

Physiotherapist and epidemiologist Subhashisa Swain, MPH, PhD, of the Nuffield Department of Primary Care Health Sciences at the University of Oxford, Oxford, England, presented an analysis of data from the multicenter European Comorbidities in Osteoarthritis (ComOA) study, which is examining electronic health records to identify associations between 61 different comorbidities with osteoarthritis and the clusters and trajectories of those comorbidities and osteoarthritis.

In this analysis, researchers looked at data from 845,373 patients with osteoarthritis and 2,556,243 age- and sex-matched controls, with both groups being around 53% women and with a mean age of around 62 years and 61 years, respectively. They chose five pain-related or psychological comorbidities to study: Fibromyalgia, CFS (also known as myalgic encephalomyelitis), gout, irritable bowel syndrome, and depression.

Researchers found that all five comorbidities were significantly associated with incident osteoarthritis, ranging from a 24% increase in risk with depression (95% CI, 1.16-1.33) to a 92% increase in risk with fibromyalgia (95% CI, 1.49-2.49).

Similarly, when looking prospectively, people with osteoarthritis had an increased incidence of all five comorbidities. Again, fibromyalgia was associated with the greatest increase in risk — 42% (95% CI, 1.29-1.57) — and the lowest was seen with CFS, which was associated with a 9% increase in the incidence of osteoarthritis.

“There is consistent bidirectional association between these five chronic conditions and osteoarthritis from observational data,” Swain told attendees.

The researchers also conducted a Mendelian randomization analysis that used UK Biobank data to look for possible causal associations that might point to underlying genetic explanations. To do this, researchers used multisite chronic pain as a proxy for fibromyalgia and tiredness as a proxy for CFS. They found that depression, CFS, and fibromyalgia all showed potential causal associations for osteoarthritis. The strongest effect was seen with fibromyalgia, which was associated with an odds ratio of 2.44 and which was also the only comorbidity that osteoarthritis in turn showed a possible causal association for.

“We wanted to see who drives what,” Swain told Medscape Medical News. “That also implies that it is a cluster of conditions, which exist together, and it’s just a matter of time which comes first and which comes later.”

As a physiotherapist, Swain said he would sometimes see patients with Kellgren and Lawrence grade 3 osteoarthritis and with very damaged joints but who don’t experience pain. “Because they practice tai chi or yoga or meditation, so their tolerance of pain is much higher,” he said. In the case of the link with fibromyalgia in particular, he said that it might be related to central pain mechanisms and sensitization.

Commenting on the presentation, session moderator and orthopedic surgeon Gun-Il Im, MD, PhD, of the Integrative Research Institute for Regenerative Biomedical Engineering at Dongguk University, Goyang, South Korea, said the findings highlight the importance of treating the whole patient, rather than simply focusing on their knee or site of pain. “You need a holistic approach to solve this problem; you need multi-specialty approach,” Im told Medscape Medical News.

He also noted that people with pain were less likely to exercise, which would in turn potentially aggravate their cardiovascular or metabolic disease, “and with poor health, you are more depressed — they are all associated,” he said.

The ComOA study was supported by the FOREUM Foundation for Research in Rheumatology, the Swedish Research Council, and the Swedish Rheumatism Association. No relevant conflicts of interest were declared.