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Intravenous Immunoglobulin Is Effective Therapy for Acute Idiopathic Thrombocytopenic Purpura

Question

  • In otherwise healthy children with acute onset idiopathic thrombocytopenic purpura (ITP), does treatment with IVIG versus no treatment result in more rapid resolution?

Clinical Bottom Lines

  1. High doses of IVIG and prednisone can produce a rapid increase in platelet counts in children with acute ITP and platelet counts under 20,000 (those at high risk for intracranial hemorrhage).
  2. The rate of platelet count response was significantly faster in those given treatment, and most rapid for those given immunoglobulin.
  3. Two patients (NNT=2) would have to be treated with IVIG compared to no treatment in order to have one whose platelet count rose above 50,000 in less than 3 days.  Three patients (NNT=3) would have to be treated with IVIG compared to prednisone for the same outcome.


Summary of Key Evidence

  1. A randomized trial of 53 patients compared intravenous immune globulin G (IVIG), oral prednisone, and placebo in the treatment of acute ITP.1
  2. Nineteen patients received IVIG at 1 gm/kg daily for two days, 18 received prednisone at a dose of 4 mg/kg (tapered over 21 days), and 16 received no therapy.  Baseline clinical characteristics were similar for all three groups.  The administration of drugs was not blinded.
  3. Prior to randomization, subjects were stratified by severity of hemostatic defect.  Inclusion criteria included: age over 6 months and under 18 years; platelet count less than 20,000; a bone marrow aspirate consistent with ITP; and no evidence of chronic ITP.
  4. Primary outcomes for the study were: number of days with a platelet count under 20,000 and the number of days required to reach a platelet count over 50,000.  Secondary outcomes were the occurrence of any adverse effect of therapy.
  5. Median duration of severe thrombocytopenia after treatment was 1 day for IVIG (p<0.001) and 2 days for prednisone (p<0.01) compared to 4 days for no therapy.  Results between the two treatment groups were not significantly different.
  6. The median time to reach a platelet count above 50,000 was 2 days for those in the IVIG group (statistically different than both prednisone and no therapy)
  7. Seventy-five percent of those treated with IVIG had some combination of nausea, vomiting, headache, and fever.  The most common adverse reaction to prednisone was weight gain.

Additional Comments

  • The main reason for treating children with acute ITP is the prevention of intracranial hemorrhage (ICH), a complication that occurs in 1% of affected children.  Randomized studies would require prohibitively large numbers of patients in order to use this as an outcome of interest.
  • Given that acute ITP in childhood is usually self-limited disease, the inclusion of a no-therapy group in this study is helpful (and rather unique among other published studies).  Both therapies performed better than no therapy.
  • Cost and availability of IVIG are important considerations.

Citation

  1. Blanchette VS, Luke B, Andrew M, et al.  A prospective, randomized trial of high-dose intravenous immune globulin G therapy, oral prednisone therapy, and no therapy in childhood acute immune thrombocytopenic purpura.  J Pediatr 1993; 123:989-95.

CAT Author: Luisa Madronero, MD

CAT Appraisers: John Frohna, MD

Date appraised: January 25, 1999

Last updated June 15, 2003
Department of Pediatrics and Communicable Diseases
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