Association of primary immune thrombocytopenia and common allergic diseases among children

Growing evidence has revealed a link between autoimmune and allergic diseases. However, few studies have assessed the relationship between allergic diseases and primary immune thrombocytopenia (ITP), an autoimmune disease frequently occurring in children. This population-based case–control study investigated the association between common allergic diseases and the subsequent risk of developing ITP during childhood. This study investigated 1,203 children younger than 18 y of age who were diagnosed with ITP between 1998 and 2008, as well as 4,812 frequency-matched controls. The odds ratios of the association between ITP and preexisting allergic diseases were calculated. Children with every type of allergic disease examined in this study (except asthma) exhibited an increased risk of developing ITP; the lowest adjusted odds ratio (aOR) was 1.39 for allergic conjunctivitis (95% confidence interval (CI) = 1.09–1.79), whereas the greatest aOR was 1.84 for allergic rhinitis (95% CI = 1.49–2.27). The aORs increased with the number of concurrent allergic diseases to 2.89 (95% CI = 1.98–4.22) for children with at least three allergic diseases. Children with atopic diathesis have a greater risk of subsequently developing ITP. The fundamental determinants of this relationship warrant further study.