title: Frequency of inhibitor development in severe haemophilia A children treated with cryoprecipitate and low-dose immune tolerance induction.
abstract: The frequency of factor VIII inhibitor development was evaluated in a hundred severe haemophilia A patients < 18 years of age (mean 10.4 +/- 5.1 years); 25 were previously untreated patients (PUPs), with a mean age of 11.2 +/- 2.9 months. All were followed up for 3 years from December 1996. Immune tolerance (IT) was induced with low-dose factor VIII (FVIII); 25-50 IU kg(-1) every other day for the 10 haemophiliacs who developed persistent inhibitors. The incidence of inhibitors for PUPs was 3/25 (12%; 95% confidence interval [CI], 0. 7-24.7%) and were detected after 4, 15 and 20 exposure days (mean 13 +/- 8.2 days; 95% CI, 3.7-22.2%). Children with maximum inhibitor levels of > 40 Bethesda units (BU) per mL (n=4) received IT therapy as 25 U kg(-1) FVIII in the form of cryoprecipitate every other day for 1-4 months (mean 2.4 +/- 1.6 months; 95% CI, 0.8-3.9%), which was successful in all of them. FVIII (50 U kg(-1)) was given every other day for six patients with maximum inhibitor level > 40 BU mL(-1) for 3-9 months (mean 5.4 +/- 3.2 months; 95% CI, 2.9 -7.9%) with success in 4/6 (66.6%; 95% CI, 28.8-104.3%). Patients who showed a good IT response had an inhibitor level < or = 30 BU mL(-1), were < or = 9 years of age at inhibitor development with few exposure days to FVIII and had an early immune tolerance. In conclusion, inhibitor development in severe haemophilia A children exclusively treated with cryoprecipitate is low. Early low-dose IT induction for high responders may be achieved successfully if inhibitor level is < or = 50 BU mL(-1).
authors: Department of Paediatric Haematology, Ain Shams University, Cairo, Egypt.
authors: M S
authors: MS
authors: ElAlfy
authors: M S
authors: MS
authors: El Alfy
authors: A A
authors: AA
authors: Tantawy
authors: M H
authors: MH
authors: Ahmed
authors: I A
authors: IA
authors: Abdin
mesh_terms: D000293:Adolescent; D000906:Antibodies / Q000097:blood / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005169:Factor VIII / Q000276:immunology* / Q000302:isolation & purification / Q000627:therapeutic use*; D005615:Freezing; D006467:Hemophilia A / Q000097:blood / Q000188:drug therapy* / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance; D007223:Infant
chemical_list: D000906:Antibodies; D005169:Factor VIII