Anti‐platelet antibody immunoassays in childhood immune thrombocytopenia: a systematic review

• Published in: Vox sanguinis 2020-05, Vol.115 (4), p.323-333
• Main Authors: Schmidt, David E., Lakerveld, Anke J., Heitink‐Pollé, Katja M. J., Bruin, Marrie C. A., Vidarsson, Gestur, Porcelijn, Leendert, Haas, Masja
• Format: Article
• Language: English
• Subjects: Antibodies; Autoantibodies; Autoantibodies - immunology; Bleeding; Child; Childhood; Children; clinical laboratory techniques; Control data (computers); Diagnostic systems; Evaluation; Glycoproteins; Humans; Idiopathic thrombocytopenic purpura; IgG antibody; immune thrombocytopenia; Immunoassay; Immunoassay - methods; Immunoassay - standards; Immunoassays; Immunoglobulin G; Immunoglobulin M; Immunohematology; Medicin och hälsovetenskap; Original Paper; paediatrics; Platelet Glycoprotein GPIb-IX Complex - immunology; Platelet Glycoprotein GPIIb-IIIa Complex - immunology; Platelets; Purpura, Thrombocytopenic, Idiopathic - blood; Purpura, Thrombocytopenic, Idiopathic - diagnosis; Purpura, Thrombocytopenic, Idiopathic - immunology; Quality assessment; Sensitivity; Sensitivity analysis; Sensitivity and Specificity; Serologic Tests - methods; Serologic Tests - standards; systematic review; Thrombocytopenia
• ISSN: 0042-9007; 1423-0410; 1423-0410
• DOI: 10.1111/vox.12894

Background In adult immune thrombocytopenia (ITP), an acquired autoimmune bleeding disorder, anti‐platelet autoantibody testing may be useful as a rule‐in test. Childhood ITP has different disease characteristics, and the diagnostic and prognostic value of anti‐platelet antibody testing remains uncertain. Objective To systematically review the diagnostic accuracy of anti‐platelet autoantibody testing in childhood ITP. Methods PubMed and EMBASE were searched for studies evaluating immunoassays in childhood ITP. Study quality was assessed (QUADAS2), and evidence was synthesized descriptively. Results In total, 40 studies (1606 patients) were identified. Nine studies reported sufficient data to determine diagnostic accuracy measures. Anti‐platelet IgG antibody testing showed a moderate sensitivity (0·36–0·80 platelet‐associated IgG [direct test]; 0·19–0·39 circulating IgG [indirect test]). In studies that reported control data, including patients with non‐immune thrombocytopenia, specificity was very good (0·80–1·00). Glycoprotein‐specific immunoassays showed comparable sensitivity (three studies) and predominantly identified IgG anti‐GP IIb/IIIa antibodies, with few IgG anti‐GP Ib/IX antibodies. Anti‐platelet IgM antibodies were identified in a substantial proportion of children (sensitivity 0·62–0·64 for direct and indirect tests). Conclusion The diagnostic evaluation of IgG and IgM anti‐platelet antibodies may be useful as a rule‐in test for ITP. In children with insufficient platelets for a direct test, indirect tests may be performed instead. A negative test does not rule out the diagnosis of ITP. Future studies should evaluate the value of anti‐platelet antibody tests in thrombocytopenic children with suspected ITP.