Faculty Collaboration Database

Prospective evaluation of a new platelet glycoprotein (GP)-specific assay (PakAuto) in the diagnosis of autoimmune thrombocytopenia (AITP). Am J Hematol 2005 Mar;78(3):193-7

Date

02/24/2005

Pubmed ID

15726595

DOI

10.1002/ajh.20309

Scopus ID

2-s2.0-14644439149 (requires institutional sign-in at Scopus site)   43 Citations

Abstract

Assays measuring platelet-associated immunoglobulin G (PAIgG), while highly sensitive, lack specificity in diagnosing autoimmune thrombocytopenia (AITP). We prospectively evaluated a new commercially available glycoprotein (GP)-specific assay, the PakAuto (GTI, Brookfield, WI), for its clinical usefulness in distinguishing immune from nonimmune thrombocytopenia (TP), in 216 patients with autoimmune TP (both primary "idiopathic" and "secondary") and 46 patients with TP due to other causes. This assay is designed to detect both platelet-associated (direct assay) and plasma (indirect assay) antiplatelet antibodies specific for GPs IIb/IIIa, Ib/IX, and Ia/IIa. The mean platelet counts of the immune (79 +/- 7 x 10(9)/L) and nonimmune groups (78 +/- 7 x 10(9)/L), were similar (P=0.95). The direct assay was positive in 114/216 patients with AITP (53%), and 13/46 with nonimmune TP (28%). Among the AITP group, the majority (61%) of patients with positive test results had autoantibodies reactive against all three GP targets. The sensitivity, specificity, positive, and negative predictive values for the direct PakAuto were 53%, 72%, 90%, and 24%, respectively, comparable to previously published experience of GP-specific assays. However, in some cases of TP due to nonimmune cause, the PakAuto was highly specific. Only 3 of 22 patients with gestational and 1 of 8 with familial/congenital TP had a positive direct assay, indicating that the test may be particularly useful for excluding an immune etiology for TP in certain patient subgroups.

Author List

Davoren A, Bussel J, Curtis BR, Moghaddam M, Aster RH, McFarland JG

Author

Brian Curtis PhD Director in the Platelet & Neutrophil Immunology Laboratory department at BloodCenter of Wisconsin

MESH terms used to index this publication - Major topics in bold

Adolescent
Adult
Aged
Aged, 80 and over
Antibody Specificity
Autoantibodies
Blood Platelets
Child
Child, Preschool
Diagnosis, Differential
Female
Humans
Immunoenzyme Techniques
Male
Middle Aged
Platelet Count
Platelet Membrane Glycoproteins
Predictive Value of Tests
Prospective Studies
Purpura, Thrombocytopenic, Idiopathic
Sensitivity and Specificity