Biological stratification of clinical disease courses in childhood immune thrombocytopenia
Journal of thrombosis and haemostasis : JTH. 2021
BACKGROUND In childhood immune thrombocytopenia (ITP), an autoimmune bleeding disorder, there is a need for better prediction of individual disease courses and treatment outcomes. OBJECTIVE To predict the response to intravenous Immunoglobulins (IVIg) and ITP disease course using genetic and immune markers. METHODS Children aged below seven years with newly diagnosed ITP (N = 147) from the TIKI study were included, which randomized children to an IVIg or observation group. A total of 46 variables were available: clinical characteristics, targeted genotyping, lymphocyte immune phenotyping, and platelet autoantibodies. RESULTS In the treatment arm, 48/80 children (60%) showed a complete response (platelets ≥100 x 10(9) /L) that lasted for at least one month (complete sustained response; CSR) and 32 exhibited no or a temporary response (absence of a sustained response; ASR). For a biological risk score, five variables were selected by regularized logistic regression that predicted ASR vs CSR: 1) hemoglobin; 2) platelet count; 3) genetic polymorphisms of FcγRIIc; 4) the presence of IgG anti-platelet antibodies; and 5) preceding vaccination. The ASR sensitivity was 0.91 (95% CI, 0.80 - 1.00) and specificity was 0.67 (95% CI, 0.53 - 0.80). In the 67 patients of the observation arm, this biological score was also associated with recovery during one-year follow-up. The addition of the biological score to a predefined clinical score further improved the discrimination of favorable ITP disease courses. CONCLUSIONS The prediction of disease courses and IVIg treatment responses in ITP is improved by using both clinical and biological stratification.
Anti-Platelet Antibodies in Childhood Immune Thrombocytopenia: Prevalence and Prognostic Implications
Journal of thrombosis and haemostasis : JTH. 2020
BACKGROUND Anti-platelet antibody testing may be useful for the diagnosis and management of childhood immune thrombocytopenia (ITP). OBJECTIVES Here we aimed to assess the prevalence and prognostic significance of anti-platelet glycoprotein-specific IgM and IgG antibodies. METHODS Children with newly diagnosed ITP were included at diagnosis and randomized to an intravenous immunoglobulins (IVIg) or careful observation group (TIKI trial). In this well-defined and longitudinally followed cohort (N = 179), anti-platelet glycoprotein-specific IgM and IgG antibodies were determined by MAIPA. RESULTS The dominant circulating anti-platelet antibody class in childhood ITP was IgM (62% of patients); but IgG antibodies were also found (10%). Children without IgM platelet antibodies were older and more often female. There was weak evidence for an association between IgM anti-GP IIb/IIIa antibodies and an increased bleeding severity (P=0.03). The IgM and IgG anti-platelet responses partially overlapped, and reactivity was frequently directed against multiple glycoproteins. During one year follow-up, children with IgM antibodies in the observation group displayed a faster platelet recovery compared to children without IgM, also after adjustment for age and preceding infections (P=7.1x10(-5) ). The small group of patients with detectable IgG anti-platelet antibodies exhibited an almost complete response to IVIg treatment (N=12; P=0.02), suggesting that IVIg was particularly efficacious in these children. CONCLUSIONS Testing for circulating anti-platelet antibodies may be helpful for the clinical prognostication and the guidance of treatment decisions in newly diagnosed childhood ITP. Our data suggest that the development of even more sensitive tests may further improve the clinical value of antibody testing.