Epidemiology of urticaria in Spain.

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.