The study, “Bidirectional association between fibromyalgia and gastroesophageal reflux disease: two population-based retrospective cohort analysis,” was published in the journal Pain.
The study’s senior author was Chia-Hung Kao, MD, a professor at the Graduate Institute of Clinical Medical Science and School of Medicine at the China Medical University in Taichung, Taiwan.
Patients with fibromyalgia have gastrointestinal disturbances including irritable bowel syndrome and GERD, which is characterized by gastric acid entering the esophagus, oral cavity, or the lungs, causing regurgitation and heartburn.
However, the mechanisms underlying this relationship are unclear, although animal studies have suggested that acidity in the esophagus may be a critical factor.
Patients with GERD frequently use proton pump inhibitors (PPIs) to decrease the production of gastric acid. But the long-term use of this group of drugs may alter susceptibility to bacterial pathogens in the gut and cause vitamin B12 and magnesium deficiencies, which are regarded as potential contributors to developing fibromyalgia.
In the other direction, fibromyalgia patients on PPIs for other gastrointestinal problems may also be at risk of developing GERD.
Scientists conducted a large population-based study to assess this bidirectional association between fibromyalgia and GERD, and to determine if patients with either disease have a greater risk of developing the other condition. To do this, patients were compared with healthy individuals. For the analysis, researchers used a nationwide database from the National Health Insurance of Taiwan.
Two study groups were established: The first included 35,117 fibromyalgia patients, and the second included 34,630 GERD patients. Patients were diagnosed between 2000 and 2010. The incidence of GERD in the first group and of fibromyalgia in the second was determined by the end of 2011. Controls had neither disease.
Results showed a bidirectional relationship between the two diseases. The overall incidence of GERD was 1.6-fold greater in the fibromyalgia group than in controls, after controlling for sex, age, comorbidities, and medications. Conversely, the GERD group had a 1.5-fold higher incidence of fibromyalgia than controls.
In addition, data showed that fibromyalgia patients take longer to develop GERD than GERD patients to develop fibromyalgia, which may be associated with the higher prevalence of comorbidities in the GERD group, the team said.
Furthermore, the incidence rates of either disease in the other condition’s group increased with age.
The team believes that among the possible mechanisms in fibromyalgia patients that may explain this association are psychiatric comorbidities, such as depression and anxiety, exhaustion and stress, and the lack of physical exercise, which may lead to mood disorders. In addition, sleep deprivation in GERD, which can exacerbate pain, may be another key factor.
Of note, GERD patients with peptic ulcer disease and those taking nonsteroidal anti-inflammatory drugs (NSAIDs) showed greater risk of developing fibromyalgia. This may be explained by the altered intestinal permeability in these patients.
Overall, “the present study suggests a bidirectional relationship between [fibromyalgia] and GERD,” the authors concluded. “There is a greater risk of developing GERD for [fibromyalgia] patients than developing [fibromyalgia] for GERD patients,” they added. by Jose Marques Lopez