People with rheumatoid arthritis (RA), endometriosis and inflammatory bowel disease (IBD) are at greater risk of developing fibromyalgia or chronic and widespread pain later in life, a population-based study in Sweden suggests.
The data are consistent with the central sensitization phenomena caused by these diseases, leading to onset of fibromyalgia and chronic pain, and highlight the need for pain itself to be a clinical focus in people with such conditions.
Widespread, long-lasting pain is a common symptom of several chronic diseases. Scientists suspect these pain episodes alter the way a person’s central nervous system — the brain and spinal cord — perceives pain.
It gets oversensitive and over-reactive to pain — a state called central sensitization — making a person experience pain with things that normally are not painful, like a simple touch (allodynia), and to feel more pain with stimuli that are typically not as painful (hyperalgesia).
To date, there is limited evidence supporting a cause and effect relationship between the underlying disease and the onset of widespread pain.
Researchers investigated if people with a chronic disease who have pain as a common symptom — including those with rheumatoid arthritis (RA), endometriosis, or inflammatory bowel disease (IBD) — are more prone to develop widespread pain, including fibromyalgia (FM) or chronic widespread pain (CWP), later in life.
For that, the team analyzed the health records of 889,938 adult patients followed from 2007 to 2016, and documented in the Swedish Skåne Healthcare register. Mean follow-up time was more than nine years.
People with rheumatoid arthritis served as a positive control, given that a link between this chronic disease and risk of fibromyalgia has previously been shown.
Over the study period, a total of 1,739 people with chronic widespread pain and 4,016 with fibromyalgia — translating into a final prevalence of 0.5% — were identified.
Both conditions were more common in women than in men; nearly all cases of fibromyalgia (94.9%) occurred in women and a large part (76.7%) of people with chronic widespread pain were females.
Further analysis revealed that all three investigated chronic diseases were significantly associated with greater susceptibility to fibromyalgia. Patients with RA or endometriosis also were at greater risk of chronic widespread pain.
Those with rheumatoid arthritis were nearly three times more likely to develop fibromyalgia or CWP later on, compared to patients without rheumatoid arthritis.
A similar tendency was observed in people with endometriosis — a 2.83 increased risk of fibromyalgia and a 5.02 increased risk of CWP — showing that endometriosis is a risk factor of almost equal magnitude as the better studied rheumatoid arthritis.
People with IBD were also more susceptible, with a 2.32 higher risk of developing fibromyalgia.
“In conclusion, this study shows that RA, endometriosis and IBD strongly predispose for later widespread pain, a common hypothesis previously difficult to verify due to lack of longitudinal data,” the researchers wrote.
The findings are “consistent with a hypothesis of central sensitization as an effect of a painful underlying condition,” they said, adding this could have potential implications for clinical practice with regard to awareness and treatment of pain.
“Diagnosing and treating pain conditions as diseases in their own right, also among patients suffering from other chronic disease, could improve these patients’ function and quality of life and may even avoid generalization of pain,” the team concluded.