Outcome of Intramuscular Anti-D In Children with Chronic Immune Thrombocytopenia (ITP) and Severe Thrombocytopenia: A Case-Control Study,
Authors: Sirachainan Nongnuch , Anurathapan Usanarat , Chuansumrit Ampaiwan , Songdej Duantida , Wongwerawattanakoon Pakawan , Hutspardol Sakara , Kitpoka Pimpun 
Published: October 2019

Abstract
Abstract 3285

Introduction:
Chronic ITP accounts for 20–30% of children with ITP. Treatment includes immunosuppressive agents and splenectomy to maintain platelet count above 20,000/uL. The limitation of treatment was the risk of infection and malignancy. Intravenous anti-D showed some effectiveness in patients with acute and chronic ITP; however, this medication is unavailable in some countries. Objective: To determine the effectiveness and outcome of intramuscular anti-D in children with chronic ITP. Methods: Patients, children age≤18 years, diagnosed with chronic ITP with platelet count <20,000/uL, were enrolled. Treatment protocol, intramuscular anti-D (Igamed®) of 10 mcg/kg/dose, was divided into 3 phases of varied regimens: phase I - anti-D daily for 5 days; phase II - anti-D weekly for 12 weeks and withheld when platelet counts ≥20,000/uL; and phase III - anti-D once every 2 weeks for 24 weeks. Direct Coombs' test and LDH and hemoglobin (Hb) levels were monitored on day 3, 5 and 7 during phase I; every week during phase II and every 2 weeks during phase III. The response was defined by platelet count>20,000/uL. Results: Twenty-five patients with chronic ITP, median (range) age 7.8(3.8–15.5) years, were enrolled, 9 patients [median age 11.3(4.6–15.5) years, females:males = 2:7] were treated with anti-D while 16 patients [median age 6.6(3.8–12.3) years, females:males = 4:12] were not. Median platelet count at the time of enrollment was 7,000(2,000–18,000)/uL. Median platelet counts in anti-D treatment [9,000(2,000–18,000)/uL] and non-treatment [4,500(2,000–16,000)/uL] groups at the time of enrollment were not significantly different. During phase I, the median platelet counts in all treated patients significantly increased from 9,000(6,500–14,700)/uL to 32,000(22,430–46,000)/uL, p= 0.012. The maximum response was during days 4–5 after treatment. Seven patients received anti-D weekly in phase II and every 2 weeks in phase III with a total of 84 episodes each in both phases. The results revealed platelet count≥ 20,000/uL in 21 episodes [25(8.3–78.2)%] in phase II and 25.5 episodes [30.7(0–50)%] in phase III. Direct Coombs' tests were positive (3+ to 4+) in all patients; however, Hb level was not changed. The median follow-up time after enrollment in anti-D treatment group was 2.2(0.6–3.7) years. One patient in anti-D treatment group was in remission (platelet>100,000/uL) at 1.3 and 0.8 years after diagnosis and enrollment, respectively and 8 patients in non-treatment group were in remission at median time of 4.1(1.6–5.4) and 2.0(0.8–4.2) years after diagnosis and enrollment, respectively, p= 0.22. Conclusion: Intramuscular anti-D demonstrated the 100% response when given 10 mcg/kg/dose for 5 days. The once a week and once every 2 weeks showed only 25% and 30% response, respectively. Anti-D treatment during 37 weeks did not affect the long-term outcome. No complication was detected. Therefore, intramuscular anti-D given 10 mcg/kg for 5 days can be an alternative method to raise platelet count for immediate invasive procedure requirement in chronic ITP patients with severe thrombocytopenia.

Disclosures:
No relevant conflicts of interest to declare.