Risk factors for future development of systemic lupus erythematosus in children with idiopathic thrombocytopenic purpura.

The risk of later development of systemic lupus erythematosus (SLE) in childhood idiopathic thrombocytopenic purpura (ITP) is currently unknown. We retrospectively evaluated the incidence and risk factors of this complication in 222 children with ITP who were followed for a mean of 4.2+/-4.9 years. During that time 3.6% of the children (8/222) developed SLE; all were females with positive anti-nuclear antibody (ANA), older (12.7+/-3.6 vs. 6.4+/-4.3 years old; P<0.01), and were more likely to have chronic ITP (87.5 vs. 46%; P=0.02), and had high titers of ANA. The majority of children with ITP who had a positive ANA (14/22, 64%) did not develop SLE.