BACKGROUND:

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.

METHODS:

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.

RESULTS:

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.

CONCLUSION:

Children with atopic diathesis have a greater risk of subsequently developing ITP. The fundamental determinants of this relationship warrant further study.