Epidemiology and comorbidities of patients with chronic urticaria in Taiwan: A nationwide population-based study

Background: Comprehensive data regarding the epidemiology of chronic urticaria (CU) in general populations are scant. Objectives: To investigate the prevalence, incidence, and comorbidities of CU in general population. Methods: The data were sourced from the National Health Insurance Research Database (NHIRD) for 2009-2012. Patients who had a primary/secondary ICD-9-CM diagnosis code of 708.1, 708.8, or 708.9 during the year with at least two outpatient visits and an antihistamine prescription, were identified as the cases of CU for each year. The incidence, persistence and comorbidities of CU were examined. Results: The prevalence of CU ranged from 0.69% to 0.79% for each year from 2009 to 2012, and the incidence was around 0.50% per year from 2010 to 2012. Comparing to the Standard Population, the standardized prevalence ratios (SPRs) for the rheumatic diseases, thyroid disorders, inflammatory diseases, and psychiatric disorders among CU patients were 2.74, 1.81, 1.57 and 1.87, respectively. Conclusion: The prevalence of CU in Taiwan is about 0.69-0.79%. CU is associated with a significantly increased risk of psychiatric disorders, inflammatory diseases, thyroid disorders, and rheumatic diseases. Except for thyroid disorders, the prevalence of these comorbidities tends to increase the longer CU persists. (C) 2017 Published by Elsevier Ireland Ltd on behalf of Japanese Society for Investigative Dermatology.