Assessment of the role of aeroallergens in patients with chronic urticaria

Abstract

Background The cause of chronic urticaria (CU) remains unidentified in many patients. It may include medications, food and autoimmunity. However, the possible role of inhalant allergens (aeroallergens) has not been confirmed. Objective The purpose of this study was to investigate the possible role of aeroallergens in patients with chronic idiopathic urticaria (CIU), and without allergic respiratory diseases. Patients and methods Two hundred patients with CU and no associated allergic respiratory diseases were recruited over an eight-month period from the Allergy Outpatient Clinic at Ain Shams University Hospital, Egypt. CU was diagnosed by history, physical examination and laboratory tests, which included tests for autoimmunity. Patients who had no obvious etiological factor for CU were further studied for sensitivity to common aeroallergens by skin prick test (SPT); cases that were positive for aeroallergens were further investigated by a specific IgE study. In addition, 200 healthy controls were also subjected to SPT. Results Twenty-six of 200 patients (13%) had an etiological factor for urticaria, and were excluded from the study. The remaining 174 patients (87%) were diagnosed as CIU, and underwent SPT. Skin test positivity to aeroallergens only was significantly higher among patients with CIU than among controls (17.2% as compared to 3.5%). Among patients with CIU, the most common aeroallergens were mites (13.8%), followed by pollens (5.2%), and mixed molds (4%). All these aeroallergens were significantly more prevalent among cases than among healthy controls. Multiple allergen sensitivity was also significantly more prevalent among cases than controls. Specific IgE level was elevated (superior to 0.35 kU/L) to allergens in all cases with positive SPT. Conclusion Aeroallergens should be considered as a possible etiology of CU, even if not associated with allergic respiratory diseases.