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Performance characteristics of platelet autoantibody testing for the diagnosis of immune thrombocytopenia using strict clinical criteria
Author(s) -
Gabe Caroline,
Sirotich Emily,
Li Na,
Ivetic Nikola,
Nazy Ishac,
Smith James,
Kelton John G.,
Arnold Donald M.
Publication year - 2021
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/bjh.17566
Subject(s) - autoantibody , medicine , immune thrombocytopenia , platelet , confidence interval , immunology , gastroenterology , predictive value of tests , immunopathology , antibody
Summary Misclassification of immune thrombocytopenia (ITP) is common, which might undermine the value of platelet autoantibody testing. We determined the sensitivity and specificity of platelet autoantibody testing using the direct antigen capture assay for anti‐glycoprotein (GP) IIb/IIIa or anti‐GPIbIX in patients with ‘definite ITP’, defined as those with a documented treatment response. Sensitivity of platelet autoantiboody testing increased from 48·3% [95% confidence interval (CI) 43·5–53·2] for all ITP patients to 64·7% (95% CI 54·6–73·9) for definite ITP patients. Specificity was unchanged [75·3% (95% CI 67·5–82·1)]. High optical density values (>0·8) improved the specificity of platelet autoantibody testing but lowered sensitivity. In patients with a high pretest probability, platelet autoantibodies can aid in the diagnosis of ITP and may be most prevalent in certain patient subsets.