PF707 INCIDENCE AND OUTCOMES OF REFRACTORY IMMUNE THROMBOCYTOPENIC PURPURA IN CHILDREN; A SINGLE INSTITUTION EXPERIENCE
Authors: Ito M. , Yagasaki H. , Nakahara E. , Morioka I. 
Published: June 2019

Background:The treatment of refractory immune thrombocytopenic purpura (ITP) in children is challenging. Although various medical approaches have been used to treat refractory ITP, few data are available on the long‐term incidence of outcomes in children with refractory ITP.Aims:In this study, we aimed to reveal the outcomes of 87 children with ITP in our institution during the last 19 years.Methods:We retrospectively reviewed the clinical data of children who were newly diagnosed with ITP from April 1998 to March 2017 at the Nihon University Itabashi Hospital. Patients aged below 16 years were included in this study. Patients with follow‐up duration of less than 3 months were excluded. In this study, refractory ITP was defined as a platelet count of <50 × 109 /L, which did not respond to intravenous immunoglobulin (IVIG) and prednisolone (PSL). The definition of the treatment response was as follows: complete response (CR) or partial response (PR), platelet count sustaining more than 100 × 109/L or between 50 and 100 × 109/L at 6 months after change in the treatment approach, respectively. Since 2009, we have introduced cyclosporine (CSA) for refractory ITP; we have diagnosed refractory ITP as refractory thrombocytopenia, which is a subtype of refractory cytopenia of childhood, and then we have used CSA for such patients. In this study, we compared the incidence of CR plus PR in refractory ITP at 3 years after diagnosis in the 1998–2008 group and in the 2009–2017 group. This retrospective study was approved by the institutional review board.Results:A total of 87 children with ITP were identified (50 males and 37 females): 42 children (48%) in the 1998–2008 group and 45 children (52%) in the 2009–2017 group. There were 9 patients (21%) with refractory ITP in the 1998–2008 group and 8 patients (18%) in the 2009–2017 group. Treatment chart in 17 patients with refractory ITP are shown in Figure 1. We changed the diagnosis of ITP to refractory thrombocytopenia in the all patients with refractory ITP in the 2009–2017 group, and initiated treatment with CSA. CSA was started at a dose of 4–6 mg/kg/day (per oral), and the trough level was adjusted between 100 and 150 ng/ml. Two patients achieved CR by CSA therapy alone at 16 and 119 days after starting CSA therapy, respectively. One patient achieved PR with the addition of PSL. Five patients did not respond to CSA therapy alone and then received IVIG at the CSA trough level of more than 100 ng/ml. With this approach, 4 patients achieved CR at a median time of 21 days (range, 13–38) after starting CSA therapy. Overall, 7 out of the 8 patients with refractory ITP in the 2009–2017 group maintained CR plus PR at 3 years after diagnosis. No severe CSA‐associated adverse event was seen in any patients. In contrast, only 2 out of 9 patients with refractory ITP in the 1998–2008 group achieved CR spontaneously (without additional treatment) at 3 years after diagnosis. Moreover, 2 patients obtained CR after splenectomy, and the other 5 patients remained with thrombocytopenia.Summary/Conclusion:CSA with or without IVIG therapy was effective in most cases (88%) of childhood refractory thrombocytopenia. These findings indicate that childhood thrombocytopenia is partially mediated by T cells. Although splenectomy was a conventional treatment for refractory ITP, it surely increases the long‐term risks of venous and arterial thrombosis as well as sepsis from Streptococcus pneumoniae. Therefore, CSA with or without IVIG therapy is feasible in children with refractory ITP to avoid splenectomy.image