Incidence and outcomes of refractory immune thrombocytopenic purpura in children: a retrospective study in a single institution

Treatment of children with refractory immune thrombocytopenic purpura (ITP) is challenging and poorly established. We retrospectively reviewed the clinical data of 87 patients under the age of 16 years who were diagnosed with ITP from April 1998 to March 2017 in our institution. Refractory ITP was defined as a platelet count of<50x10(9)/L at 14 days after receiving intravenous immunoglobulin (IVIG) and prednisolone. We presumed that there was a pathophysiological overlap between refractory ITP and refractory thrombocytopenia (RT): a subtype of refractory cytopenia of childhood (RCC). Immunosuppressive therapies including anti-thymocyte globulin and cyclosporine (CsA) have been adopted for children with RCC in Japan. Thus, from 2009 onwards, we changed the diagnosis from refractory ITP to RT and introduced CsA for refractory ITP/RT. Nine of 42 patients developed refractory ITP in the 1998-2008 group, who received conventional treatments such as IVIG and steroid therapy. Eight of 45 patients developed refractory ITP in the 2009-2017 group, who received CsA with or without IVIG therapy. The response rate at three years after diagnosis was significantly higher in the 2009-2017 group (98%) than in the 1998-2008 group (83%) (p=0.019). In conclusion, our strategy of introducing CsA for refractory ITP/RT contributed to better outcomes.