Epidemiology of urticaria in Spain.

Summary Background: In spite of the frequency of chronic urticaria there are very few epidemiological studies of its prevalence and distribution. Objective: We wanted to approach the real prevalence of chronic urticaria in a population-based study and to depict demographic distribution and personal perception of the disease. We also wanted to describe the frequency of acute urticaria episodes in the population studied. Methods: We conducted a population-based study among adults in Spain. We questioned 5003 individuals after calculating a sample size for a maximum variability (conservative approach p=q=0.5) Results: We found a 0.6% (95% CI: 0.4-0.8) prevalence of chronic urticaria. The prevalence is significantly higher in women than in men with a OR=3.82 (95%CI 1.56-9.37). Chronic urticaria is a self-limited disease, yet in 8.7% of cases chronic urticaria lasts from one to 5 years and in 11.3%, for more than 5 years. The average age of onset is 40 years. Conclusions: We offer large epidemiology study data on the prevalence of chronic urticaria. The prevalence of chronic urticaria has not yet been defined in an adult population-based study. With this work we offer such data to describe the prevalence and features of this disease.