Demographic data, natural history, and prognostic factors of idiopathic thrombocytopenic purpura in children: a multicentered study from Argentina.

Background: Demographics, outcome, and management of idiopathic thrombocytopenic purpura (ITP) in children present differences between countries. Although several factors influence outcome, it is impossible to predict at diagnosis which patients will have acute or chronic disease. High rates of spontaneous remission in chronic ITP have been reported.

Procedure: Data concerning 1,683 patients with ITP diagnosed from 1981 to date are presented; outcome was evaluated in 1,418 children.

Results: Remarkable presenting features were an incidence peak in the first 2 years of age and male predominance in patients <24 months of age. Three age groups with different recovery rates (P < 0.001) were established (2-12 months: 89.8%; 1-8 years: 71.3%; 9-18 years: 49.0%). Platelet count <10 x 10(9)/L and history of previous illness were associated with higher remission rates only in patients >12 months of age. The score developed by the NOPHO Group showed a predictive value of 83.9% for acute ITP. Spontaneous remission between 6 months and 11 years from diagnosis was achieved by 107 of 325 (32.9%) non-splenectomized children with chronic ITP, and in 44.9% of them between 6 and 12 months from diagnosis.

Conclusions: Age and score were main prognostic factors. Infants <1 year of age are a special group with a brief course and very high recovery rate that are not influenced by other prognostic factors. Definition of groups based on age and scoring could be useful to establish differential management guidelines. The cut-off value to define chronic ITP should be changed to 12 months.