title: Combination testing for antibodies in the diagnosis of coeliac disease: comparison of multiplex immunoassay and ELISA methods.
abstract: BACKGROUND
  Tissue transglutaminase (TTG) antibodies and newly developed deamidated gliadin peptide (DGP) antibodies have better accuracy than native gliadin antibodies. Multiplex immunoassay (MIA) measures multiple antibodies simultaneously providing a complete antibody phenotype with reduced turnaround time and cost.
  
  
  OBJECTIVE
  To evaluate the agreement between MIA and enzyme-linked immunosorbent assay (ELISA) test results for coeliac autibodies in biopsy-proven coeliac patients and controls and to model the diagnostic utility of combination testing.
  
  
  METHODS
  We compared the sensitivity, specificity and accuracy of MIA and ELISA methods for TTG and DGP antibodies in mainly adult untreated coeliac patients (n = 92) and controls (n = 124).
  
  
  RESULTS
  There was excellent agreement and a significant correlation between the results of MIA and ELISA methods (k > 0.8, r > 0.7) for all tests, except IgG. Diagnostic indices of individual and combination tests measured by the MIA method did not differ significantly from those measured by ELISA. The combination tests slightly increased sensitivity (if any test was positive) and specificity (if all tests were positive) compared to the individual tests.
  
  
  CONCLUSIONS
  Multiplex immunoassay testing for antibodies is as accurate as ELISA for coeliac disease diagnosis and has practical advantages over ELISA method. Rational combination testing can help identify patients who need intestinal biopsy and may reduce unnecessary biopsies.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: S
authors.initials: S
authors.lastname: Rashtak
authors.forename: M W
authors.initials: MW
authors.lastname: Ettore
authors.forename: H A
authors.initials: HA
authors.lastname: Homburger
authors.forename: J A
authors.initials: JA
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood*; D001706:Biopsy; D016022:Case-Control Studies; D002446:Celiac Disease / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D003627:Data Interpretation, Statistical; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D000906:Antibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G