Treatment of Idiopathic (autoimmune) Thrombocytopenic Purpura (ITP): A Single Mexican Institution Experience

Background: ITP is an autoimmune disorder in wich an IgG autoantibody is formed that binds to platelets. The platelet autoantibody may bind complement, but platelets are not destroyed by direct lysis, rather, destruction takes place in the spleen, where splenic macrophages with Fc receptors bind to antibody coated platelets. It has an incidence from 50 to 100 cases per million persons per year and half of these occur in children. The infantile form affects both sexes the same, with greater incidence between the 2 and 4 years, major bleeding is common, the response to the treatment is good and mortality is low. In the adult form, women are effected more the men in relation 3 to 1, specially between 15 and 40 years, with minor bleeding, it may requires long treatment and it has greater mortality. The diagnosis is based in medical history and physical examination, valuing the type of bleeding and data of systemic diseases that can cause thrombocytopenia; by laboratory the CBC is necessary, coagulation tests, immunological panel and study of bone marrow, antiplatelet autoantibodies are not necessary; in special cases the imaging studies will be indicated. The treatment is established by guides from the American Society of Hematology.

Material and methods: consecutive patients with newly diagnosed ITP were enrolled between October 2004 and April 2008 to study the treatment, response, evolution, fatality and current status. Ambulatory patients received prednisone (PDN), and hospitalized patients received methylprednisolone (MPD). In these second groups platelets transfusions were given as necessary.

Results: 88 patients were eligible: 24 were 15 years or younger and 64 were older. Among infantile patients relation female/male was of 1 to the 1 (12/12), major bleeding in 29% (7/24), platelet count less than 20,000 per cubic millimeter in 83% (20/24), chronic course 12% (3/24), no death by any cause, the lab studies without immunological alterations. In the adult patients relation female/male was of 3 to 1 (48/16), major bleeding 23% (15/64), platelet count less than 20,000 per cubic millimeter in 43% (28/64), chronic course 23% (15/64), death by hemorrhage 3% (2/64), nonrelated deaths 8% (5/64), only one patient had positive autoimmune panel without systemic autoimmune disease. Initial treatment with MPD in 45 patients, 8 evolved to chronic disease (18%) and was 7 deaths; 43 patients received PDN as initial treatment, 6 evolved to chronic disease (14%) and had not fatalities in this group. Refractory to steroids patients from both groups received other treatments: 12 (2 children) splenectomy with 8 in complete response, 2 (one child) with chronic disease in complete remission with azathioprine; and 2 deaths without any response; 2 patients did not accept splenectomy and are receiving azathioprine with complete response. Thirteen patients received platelet transfusions, 6 evolved to chronic disease and 7 deaths: 2 by hemorrhage and 5 by non related causes, mainly sepsis.

Conclusions: similar epidemiology that is reported in the world; minor frequency of immunological alterations; the majority of patients had remissions with initial treatment and in the evolution to chronic disease it does not concern the initial treatment, but platelet transfusions do; greater mortality of the MPD arm due to a more aggressive disease.