Text Box: CLINICAL BEHAVIOR OF CHRONIC IDIOPATHIC THROMBOCYTOPENIA (ITP) IN CHINESE CHILDREN Wong MSC, Chan GCF, Ha SY, Lau YL Department of Paediatrics, Queen Mary Hospital, University of Hong Kong, HK, China Objectives: The reported clinical course and treatment outcome of childhood chronic ITP are quite variable. We attempted to identify its pattern in Chinese children. Methods: A retrospective review (Jan 1990 to Dec 2000) of children with low platelet count (plt <150x109/L) for more than 6 months without identifiable cause were performed. The indication of treatment was when plt £20x109/L. Remission is defined as plt ³150x109/L. Results: Thirty-four children were identified within this 11 years (yr). Their median age at diagnosis was 6.7 yr. (range from 0.4 to 16.8 yr.). M: F was 15:19. Bone marrow aspiration was performed in 30/34 cases. The median plt count at presentation was 24x109/L (range 2 to 135x109/L). 16/34 (47%) children eventually achieved remission, their chance of remission at 1st, 2nd, 3rd, 4th and 5th years after diagnosis were 3%, 12%, 24%, 38% and 47% respectively. For the 18 children with persistent low plt, their median follow-up was 3.5 yr. (range 0.9 to 5.9 yr.). Concerning therapy, 17/34 (50%) required no treatment while for the remaining 17, treatments including steroid (n=10), IVIg (n=10) or splenectomy (n=3) could induce prolonged complete remission (plt >150x109/L) in only 2 patients despite usual temporary improvement. 26/34 had abnormal autoimmune marker(s) at presentation but none evolved into specific autoimmune disease later on. There was no correlation between the remission status, response to treatment and the presence of autoimmune markers. No life threatening bleeding was recorded in our cohort. Conclusion: About half of our chronic ITP patients achieved remission within 5 years. Medical treatment does not seem to alter the natural course of the disease but they could induce transient response in most cases. Positive autoimmune markers are common among chronic ITP patients and have no significance in predicting outcome. 2393