Chronic urticaria in blacks: Is autoimmunity an important etiological factor?

Background: The etiology and pathophysiology of chronic urticaria is poorly understood with several implicated factors. The role of autoimmunity has been explored by several studies with such studies on chronic urticaria lacking in the black population despite the significant morbidity caused by chronic urticaria. Aim: We assessed the possible contribution of autoimmunity in the etiology of chronic urticaria using autologous serum skin testing (ASST). Materials and Methods: Sixty consecutive patients with chronic spontaneous urticaria (CSU) with age- and sex-matched controls in a ratio of 2:1 had ASST done for comparison. Student's t-test and Chi-square were used to compare means and percentages, respectively. Results: The male:female ratio of CSU was 1:2.5 with females presenting more often. The ASST was noted to be significantly positive in patients compared to controls with a positivity rate of 68.3% in the former compared to 16.7% in the latter (P = 0.0001). A higher incidence of angioedema was also documented in patients with a positive ASST in association with urticaria (23/28, P = 0.04). Conclusion: Overall, we conclude from our study that autoimmunity may be a possible cause of chronic urticaria in Nigerians which may also be extrapolated to other black population. Patients with positive ASST may have more severe disease which may be important when educating and counselling the patients about the course of the disease. This study is the first to assess the possible role of autoimmunity in a predominantly black population and will serve as a baseline for future studies.