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

Few population-based studies have focused on the epidemiology and comorbidities of chronic urticaria (CU) or chronic spontaneous urticaria (CSU). The objective of this study was to obtain information on the epidemiology and comorbidities associated with CU and CSU in Korea. We conducted a cross-sectional analysis using a national health insurance database. An algorithm based on the International Classification of Diseases, 10th revision, was used for the identification of patients with CU and CSU, and an age-sex adjusted logistic regression model was used to assess the risk of comorbidities in these patients. The average annual prevalence rates of CU and CSU during the 4-year period between 2010 and 2013 were 3.08% and 1.40%, respectively. The prevalence rates of CU and CSU were higher in women than men (1:1.39 and 1:1.34, respectively) and peaked at 0-9 and 70-79 years, respectively. After adjustment for age and sex, the patients with CU and CSU were found to have a significantly higher prevalence rate of CU/CSU-related diseases, compared with those without CU (mean adjusted odds ratio, 8.46; 95% confidence interval, 8.10-8.83). Allergic rhinitis, drug allergies, asthma, thyroid diseases and cancers were the most common comorbidities. Stomach, thyroid, liver and prostate cancers were the most prevalent cancers. This study provides large epidemiological data on the prevalence rates of CU and CSU, and their comorbidities, in Korea. Patients with CU and CSU impose a higher burden, in terms of specific comorbidities, than those without CU.