Clinically diagnosed urticaria and risk of systemic lupus erythematosus in children: A nationwide population-based case-control study

Background Urticaria is one of the most common diseases seen in clinical practice, whereas several reports have proposed that urticaria may have a link with autoimmune disorders. Few studies have examined the clinical association between urticaria with systemic lupus erythematosus (SLE). By conducting a nationwide population-based case-control study in Taiwan, we evaluated the risk of SLE in children with a prior clinical diagnosis of urticaria. Methods Using 2000-2011 claims data from the Taiwanese National Health Insurance Research Database, we identified 2105 SLE children during 2004-2011 as the study group, along with randomly selected 8420 non-SLE patients matched (1:4) for age, sex, and first diagnosis date as the control group. The correlation between urticaria and SLE risk was estimated using conditional logistic regression analysis. Results The prevalence rates of clinically diagnosed acute and chronic urticaria in SLE patients were 22.09% and 18.24%, respectively. A significant association was found between clinically diagnosed urticaria and childhood SLE, with a stronger risk associated with more episodes of urticaria (>= 3 visits, OR: 2.33, 95% CI 1.91-2.84). The risk was higher with chronic urticaria (OR: 2.21, 95% CI 1.85-2.64) than with acute urticaria (OR: 1.54, 95% CI 1.34-1.76). Subgroup analysis stratified by sex or age indicated that the risk associated with SLE was significantly greater among female children and adolescents with urticaria. Conclusions Our results suggest that children with urticaria have a significantly higher risk of SLE, with the risk increasing further among those with more episodes of urticaria or chronic urticaria.