Prevalence of fibromyalgia in a Brazilian series of patients with multiple sclerosis

Background The prevalence of pain in patients with multiple sclerosis is remarkable. Fibromyalgia has been considered as one of the forms of chronic pain encompassed in multiple sclerosis, but data are restricted to studies from Europe and North America. Objective To assess the prevalence of fibromyalgia in a series of Brazilian patients with multiple sclerosis and the characteristics of this comorbidity. Methods The present cross-sectional study included 60 consecutive adult patients with multiple sclerosis. Upon consent, participants underwent a thorough evaluation for disability, fatigue, quality of life, presence of fibromyalgia, depression, and anxiety. Results The prevalence of fibromyalgia was 11.7%, a figure similar to that observed in previous studies. Patients with the comorbidity exhibited worse scores on fatigue (median and interquartile range [IQR]: 68 [48–70] versus 39 [16.5–49]; p < 0.001), quality of life (mean ± standard deviation [SD]: 96.5 ± 35.9 versus 124.8 ± 28.8; p = 0.021), anxiety (mean ± SD: 22.7 ± 15.1 versus 13.8 ± 8.4; p = 0.021), and depression (median and IQR: 23 [6–28] versus 6 [3–12.5]; p = 0.034) indices than patients without fibromyalgia. There was a strong positive correlation between depression and anxiety scores with fatigue (r = 0.773 and r = 0.773, respectively; p < 0.001). Conversely, a moderate negative correlation appeared between the Expanded Disability Status Scale (EDSS), fatigue, and depression scores with quality of life (r= −0.587, r= −0.551, r= −0.502, respectively; p < 0.001). Conclusion Fibromyalgia is a comorbidity of multiple sclerosis that can enhance fatigue and decrease quality of life, although depression, anxiety, and disability are factors that can potentiate the impact of the comorbidity.