The severity of fibromyalgia syndrome (FMS) symptoms—with generally continuing high levels of self-reported symptoms and distress for most patients—does not show clinically meaningful improvement over time. However, up to about 25% of patients report at least moderate improvement.
Walitt and associates conducted a longitudinal study to assess 1555 patients who had a diagnosis of FMS from US rheumatologists. All patients completed 2 or more semiannual questionnaires. Physical component summary and mental component summary scores were calculated. Change in FMS symptom severity was assessed by comparing data at the first and last observations over a mean study duration of 4 years.
The mean FMS severity score was 22.7 at study onset and had an estimated 5-year improvement of 1.8 units. The 5-year improvement for pain, fatigue, and sleep was 0.4 units; there was no improvement in patient global severity. At the last observation, about 10% of patients had a substantial response, about 14% had a moderate response, and about 54% had no response. Overall, FMS severity worsened in 35.9% of patients and pain in 38.6%.
The authors noted that their data provide clinicians and patients with realistic expectations on the course of FMS in routine clinical care.