Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disorder characterized by very low platelet counts and a resulting risk of severe bleeding complications. Primary, immune-mediated ITP is treated with therapies ranging from splenectomy to intravenous immunoglobulin, treatments for which the risks sometimes outweigh the benefits. ITP can also occur secondary to other disorders, including HIV infection, chronic hepatitis C infection, myelodysplastic syndromes, and as a consequence of cancer chemotherapy.
There are currently limited therapeutic options for the management of ITP and often these may be inappropriate for some patients with ITP. However, there are new therapies for ITP on the horizon, and it is important that clinicians are kept informed on the latest clinical trial results. This education will help hematologists, oncologists, and other health care professionals managing patients with ITP and related thrombocytopenic complications in the areas of diagnosis and management of ITP in a wide variety of clinical situations.
ITP is one of the most common forms of autoimmune disease affecting adults and children. It occurs with an incidence of approximately 5-10 per 100,000 persons per year among adults and approximately 4-5 per 100,000 per year in children.1,2,3 In children, the prevalence of ITP is reported to be 4.6 per 100,000 in Europe and 7.2 per 100,000 in North America, while the prevalence for adults in the US is 9.5 per 100,000.4,5 There is general agreement that the disorder occurs with a female preponderance and some agreement that it occurs most frequently in young adults (with a peak of occurrence between 15 and 40 years), although increasing incidence with age has been reported.6,5
In addition to classification based on patient age, ITP is classified by duration of thrombocytopenia (acute or chronic).5,7 Acute ITP refers to duration of 6 months or less and is the form most commonly seen in children.2 The features of ITP in children are often different from those in adults. Childhood acute ITP is typically manifested by the rapid onset of severe thrombocytopenia that often occurs following a viral illness and is frequently self-limiting, remitting spontaneously without treatment in about 80% of cases.2 In contrast, chronic ITP is the dominant form occurring in adults, typically with an insidious onset with no preceding viral illness and rare spontaneous remission.8 Chronic ITP may persist for as long as 30 years and can be associated with platelet counts remaining at one-third to one-half of the normal value of 150 x 109/L.2 A chronic form of ITP, similar to that seen in adults, is seen in 10-15% of children.8 The long-term outlook for the majority of individuals with chronic ITP, however, is generally favorable.2,9