title: Diabetes Antibody Standardization Program: First evaluation of assays for autoantibodies to IA-2β.
abstract: OBJECTIVE
  Autoantibodies to IA-2β (IA-2βA) are important risk markers of type 1 diabetes. We report the first Diabetes Antibody Standardization Program (DASP) evaluation of IA-2βA assays.
  
  
  METHODS
  Thirteen laboratories from nine countries received coded sera from 50 patients with newly diagnosed type 1 diabetes and 100 healthy blood donors. IA-2βA results were analyzed using receiver operating characteristic (ROC) curves. Concordance of antibody levels was compared using counts per minute (cpm), local and standard curve-derived common units.
  
  
  RESULTS
  Median laboratory-assigned sensitivity was 47% (interquartile range [IQR] 45-51), specificity 98% (IQR 95-99), adjusted sensitivity at 95% specificity 50% (IQR 49-53), and area under the ROC curve 0.70 (IQR 0.69-0.73). Use of common IA-2βA units improved concordance between assays compared with local units and cpm (P < 0.0001).
  
  
  CONCLUSIONS
  IA-2βA assays in multiple laboratories worldwide achieved good concordance and high specificity for type 1 diabetes. IA-2βA are suitable for inclusion in autoantibody testing for risk assessment in prediabetes.
authors.affiliation: Department of Medical Biochemistry and Molecular Biology, Research Group of Predictive Diagnostics,University ofGreifswald, Karlsburg, Germany. polly.bingley@bristol.ac.uk
authors.forename: Michael
authors.initials: M
authors.lastname: Schlosser
authors.forename: Patricia W
authors.initials: PW
authors.lastname: Mueller
authors.forename: Peter
authors.initials: P
authors.lastname: Achenbach
authors.forename: Vito
authors.initials: V
authors.lastname: Lampasona
authors.forename: Polly J
authors.initials: PJ
authors.lastname: Bingley
mesh_terms: D019540:Area Under Curve; D001323:Autoantibodies / Q000097:blood* / Q000276:immunology; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000592:standards*; D059021:Laboratory Proficiency Testing; D008297:Male; D012372:ROC Curve; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8 / Q000032:analysis* / Q000276:immunology; D012015:Reference Standards; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8