Natural course of childhood chronic immune thrombocytopenia using the revised terminology and definitions of the international working group: a single center experience

BACKGROUND: The immune thrombocytopenia (ITP) criteria were newly standardized by the International Working Group. Thus, we analyzed the natural course of childhood chronic ITP to predict the prognosis based on the revised criteria. METHODS: The medical records of children with chronic ITP from May 2000 to February 2013 in our institute were reviewed. RESULTS: Forty-seven children with chronic ITP who were not undergoing corticosteroid therapy were included. Their initial platelet count was 23±25×10(9)/L, and age at diagnosis was 6.3±4.1 years. The follow-up period was 5.4±3.7 years. Among them, 44.7% (21/47) showed spontaneous remission and maintained a platelet count ≥100×10(9)/L. And 66.0% (31/47) maintained a platelet count ≥50×10(9)/L until the last follow-up date. The time periods required for the platelet count to be maintained ≥50×10(9)/L and ≥100 ×10(9)/L were 3.1±2.7 and 3.6±2.7 years. Age at diagnosis in the ≥50×10(9)/L group (5.7±4.4 years) was significantly lower than the age at diagnosis in the <50×10(9)/L group (7.4±3.3 years) (P=0.040). And follow-up period was the factor influencing prognosis between the ≥100×10(9)/L group and <50×10(9)/L group (P=0.022). CONCLUSION: Approximately 45% of children with chronic ITP recovered spontaneously about 3-4 years after the diagnosis and 2/3 of patients maintained a platelet count ≥50×10(9)/L, relatively safe state. Age at diagnosis of ITP and follow-up period were the factors influencing prognosis in this study.