Randomized trial of anti-D immunoglobulin versus low-dose intravenous immunoglobulin in the treatment of childhood chronic idiopathic thrombocytopenic purpura

Abstract

Background: Chronic idiopathic (immune) thrombocytopenic purpura (ITP) develops in approximately 20% of children with acute ITP. Six years ago, low-dose intravenous immunoglobulin (IVIG) treatment of childhood ITP was started at the Pediatric Hematology Unit, Ain Shams University, while intravenous anti-D has been introduced in Egypt in 2001.

Objectives: To assess the efficacy and safety of intravenous anti-D compared to low-dose IVIG in the treatment of children with chronic ITP.

Patients and methods: This randomized trial comprised 34 patients with chronic ITP (18 boys and 16 girls) with recurrent bleeding episodes. Median age of the patients was 6.5 years, duration of thrombocytopenia was > 6 months, and platelet count (PC) was < 30 x 10(9)/l (30 K). The patient cohort was divided into two subgroups: group A comprised 18 patients treated with anti-D in a dose of 50 microg/kg i.v. initially, and in 12 of them repeated doses (50 microg/kg) were given every 4 weeks, and group B consisted of 16 children who received IVIG in a dose of 250 mg/kg for 2 consecutive days. Bleeding manifestations, complete blood cell and reticulocyte counts were assessed at baseline and 3, 7, 14 and 28 days after infusion.

Results: Clinically, more than 80% of the patients (82.3%) showed good control of bleeding. On day 3, 33.3% of group A versus 37.5% of group B, and on day 7: 66.6% of group A versus 75% of group B patients demonstrated a good response (PC > 50 K and/or doubling of baseline PC). On days 14 and 21, no significant changes in PCs were observed between both groups. However, only 11.1% of group A and 12.5% of group B patients could maintain PC > 100 K on day 28, while 38.8 versus 37.5% of group A and group B, respectively, still had PC > or = double the initial count. The peak response to anti-D was noticed 7 and 14 days following infusion and to IVIG on days 3 and 7. Repeated doses of anti-D could maintain PC > 50 K (or > double the baseline PC) in 75% of patients 1 week after infusion, and in 60% of them by day 28, with good control of bleeding. Splenectomy was postponed and/or avoided in 4 (33.3%) patients on anti-D maintenance therapy who experienced recurrent severe bleeding episodes before starting therapy. The safety of anti-D was judged by the degree of intravascular hemolysis. The mean hemoglobin decrease was 0.8 +/- 0.4 g/dl; in 61.1% of patients the Hb level dropped but none of them experienced a drop of more than 3 g/dl or required transfusion.

Conclusion: Both single intravenous anti-D and low-dose IVIG effectively increased PC in children with chronic ITP at risk of bleeding or those with previous bleeding episodes. Repeated doses of anti-D could maintain PC above the critical values or double baseline counts in nearly two thirds of the patients showing good control of bleeding and may serve as an alternative to splenectomy in these patients.