The evaluation of prevalence of fibromyalgia in patients with chronic urticaria

BACKGROUND The pathophysiology of chronic idiopathic urticaria (CIU) is not fully understood; however, it has been hypothesized that a subset of people with CIU may have an autoimmune disease and that peripheral cutaneous nerve fibers may be involved in CIU. Similarly, it has been postulated that fibromyalgia syndrome (FMS) is an autoimmune disorder and may be associated with alterations of peripheral cutaneous nerve fibers. Accordingly, the present study aimed to determine whether the frequency of FMS is higher in patients with CIU. MATERIAL/METHODS A total of 72 patients with CIU and 67 sex- and age-matched healthy controls were included. Urticaria activity score (UAS), fibromyalgia impact questionnaire (FIQ), tender point number, and visual analogue scale (VAS) were assessed. RESULTS The frequency of FMS was similar between the groups (9.7% vs. 4.5%, p=0.32). However, symptom duration of FMS was significantly longer, and tender point number and FIQ were significantly higher in patients with CIU than in controls. In addition, patients with CIU had significantly higher VAS scores. UAS was significantly correlated with presence of FMS, symptom duration of FMS, tender point number, and FIQ and VAS scores. Logistic regression analysis revealed that UAS was an independent predictor of presence of FMS (b=0.34, p=0.003). CONCLUSIONS Frequency of FMS was slightly, but not significantly, higher in patients with CIU than in controls. However, symptom duration of FMS, tender point number, and FIQ and VAS scores were significantly higher in patients with CIU, and UAS reflecting severity of the disease was significantly and independently associated with presence of FMS.