Patients with fibromyalgia may experience fluctuations in symptoms over time, which may affect diagnosis and treatment, according to the study “Progression of fibromyalgia: results from a 2-year observational fibromyalgia and chronic pain study in the US,” recently published in the Journal of Pain Research.
Fibromyalgia is a disorder characterized by chronic widespread pain (CWP) accompanied by fatigue, sleep problems, and painful tender points. Because there is no specific laboratory test that can be used to diagnose fibromyalgia patients, assessment of signs and symptoms by physicians is the only reliable means for diagnosis.
There are widely variable prevalence estimates for fibromyalgia, which may range from less than 1 percent to 10.5 percent worldwide. This may be a result of symptom fluctuation in patients over time. In fact, although little is known about the behavior of fibromyalgia symptoms over time, studies have reported that one to two years after diagnosis, a high number of patients (20-47 percent) no longer meet the diagnostic criteria for fibromyalgia.
Researchers led by Edgar H. Adams wanted to better understand the fluctuations of fibromyalgia over a two-year period.
The cohort study examined 475 subjects recruited online who visited a site for physician evaluation of fibromyalgia (FM), and completed an online questionnaire to screen for chronic widespread pain (CWP). Depending on their diagnosis, patients were divided into three groups: those who had CWP and received physician diagnosis of fibromyalgia (FM+CWP+); patients with CWP but not diagnosed with fibromyalgia (FM-CWP+); and those who screened negative for CWP (FM-CWP-).
At a two-year follow-up, 226 patients participated, including 63 from the FM-CWP- group, 87 from the FM-CWP+, and 76 who had been included in the FM+CWP+ group. Among the FM+CWP+ subjects, 73.7 percent (56 out of 76) still met the study definition for fibromyalgia, whereas 11 patients transitioned to the FM-CWP- group and nine to the FM-CWP+ group.
Furthermore, two patients that had been included in the FM-CWP-, and eight from the FM-CWP+ group, met the study definition of fibromyalgia at follow-up. At baseline, these patients reported higher number of tender points and decreased physical function, compared to the patients who did not develop fibromyalgia.
The investigators also report that 76.7 percent of patients who transitioned in or out of the FM+CWP+ group experienced changes in the number of positive tender points, CWP, or both.
“The results suggest that some patients may experience fluctuation in symptoms, such as pain, physical function, and sleep over time, which may reflect the waxing and waning nature of fibromyalgia,” the authors concluded in their study.