Classification of immune thrombocytopenia (ITP). The name ITP changed from idiopathic thrombocytopenic purpura to immune thrombocytopenia in recognition of5the immune-mediated mechanism of disease and the low rates of purpura and other bleeding symptoms. Classifications include primary ITP (no underlying condition that may be associated with thrombocytopenia) vs. secondary ITP (underlying condition, such as autoimmune disease, infection, cancer or medications), phases of disease (newly diagnosed ITP [within 3 months from diagnosis], persistent ITP [lasting between 3 and 12 months] or chronic ITP [lasting > 12 months]), and severity of disease (severe vs. refractory). Severe ITP is presence of clinically relevant bleeding symptoms at presentation sufficient to mandate treatment, or the occurrence of new bleeding symptoms requiring additional therapeutic intervention with a different platelet-enhancing agent or an increased dose. Refractory ITP describes cases that fail splenectomy and exhibit severe ITP or have a risk of bleeding that requires therapy. Non-splenectomized patients are defined as responders and non-responders to various drug therapies, and are not generally considered refractory (though some authorities now use the term refractory ITP to describe failure to respond to multiple therapies whether or not they include splenectomy, since splenectomy is not performed as often as it once was).
