A prospective comparative study of 2540 infants and children with newly diagnosed idiopathic thrombocytopenic purpura (ITP) from the Intercontinental Childhood ITP Study Group.

Objective: To analyze prospectively the impact of age at diagnosis in childhood idiopathic thrombocytopenic purpura (ITP).

Methods: International registry from June 1997 to May 2001, with analysis of data from baseline and 6-month-follow-up questionnaires.

Results: Data from 2540 patients were analyzed, including 203 infants (7.6%), 1860 children > or =1 to <10 years of age (69.1%), and 477 children and adolescents between > or =10 and <16 years of age (17.7%). The mean platelet count at diagnosis was similar in all three groups, as was the percentage of patients with initial platelet count <20x10(9)/L. The male/female ratio was highest in infants and decreased with age (P=.009). Immunoglobulin therapy was used more often in infants and corticosteroids in patients > or =10 years of age. Follow-up information at 6 months was available for 1742 children (68.6%). Chronic ITP was seen less frequently in infants (23.1%) than in children >10 years of age (47.3%, P<.0001). Intracranial hemorrhage occurred in 3 of 1742 children during the first 6 months after the diagnosis of ITP.

Conclusions: Pediatric patients with ITP from infancy to adolescence exhibit heterogeneity in clinical, demographic, and treatment factors.