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.