RESUMEN
BACKGROUND: The aetiology of chronic urticaria is heterogeneous. Physical urticaria (PU) is estimated at around 35%, autoimmune urticaria (AIU) at 25% and chronic idiopathic urticaria (CIU) at 35% of all chronic urticaria cases. METHODS: Differences in clinical and laboratory parameters among AIU, PU and CIU groups were examined. AIU was diagnosed if the basophil CD63 assay was positive. Demographic data, severity of symptoms and association with allergic and autoimmune diseases were analysed by the aid of a questionnaire. Immunoassays were carried out and the effectiveness of therapy was also investigated. RESULTS: Concerning the urticaria score, AIU patients had significantly higher total urticaria scores than patients with CIU (p = 0.013), dermatographic urticaria (p = 0.05) or cholinergic urticaria (p = 0.038). Between CIU and dermatographic urticaria and between CIU and cholinergic urticaria patients, we found insignificant differences in the urticaria score (p = 0.707 and p = 0.336, respectively). AIU was more frequently associated with autoimmune diseases in the personal history (p < 0.001) and with other types of urticaria in the family history (p < 0.001). Also, anti-thyroid antibodies were more frequently detected in the AIU group. Antihistamine therapy was less effective in the AIU group (12.8%) than in the PU (70.3%) and CIU groups (68.6%), but there were no significant differences between the CIU and PU groups regarding the effectiveness of antihistamine therapy. CONCLUSION: The autoimmune subgroup represents the most severe form of chronic urticaria. On the other hand, there were no significant differences between the CIU and PU groups neither in urticaria scores nor in response to antihistamine therapy.