title: Diagnostic accuracy of the anti-glutamic acid decarboxylase antibody in type 1 diabetes mellitus: Comparison between radioimmunoassay and enzyme-linked immunosorbent assay.
abstract: OBJECTIVE
  The distributer of the anti-glutamic acid decarboxylase antibody assay kit using radioimmunoassay (RIA) recently announced its discontinuation, and proposed an alternative kit using enzyme-linked immunosorbent assay (ELISA). The aim of the present study was to investigate the diagnostic values of the anti-glutamic acid decarboxylase antibody by RIA and ELISA among type 1 diabetes mellitus patients and control participants.
  
  
  METHODS
  A total of 79 type 1 diabetes mellitus patients and 79 age-matched controls were enrolled and assessed using RIA and ELISA. Sensitivity, specificity, positive predictive values and negative predictive values were calculated for cut-off values (RIA = 1.5 U/mL and ELISA = 5.0 U/mL, respectively). Kappa coefficients were used to test for agreements between the RIA and ELISA methods regarding the diagnosis of type 1 diabetes mellitus.
  
  
  RESULTS
  The sensitivity, specificity, positive predictive values, and negative predictive values for diagnosing type 1 diabetes mellitus were 57.0, 97.5, 95.7, and 69.4% by RIA, and 60.8, 100.0, 100.0 and 71.8% by ELISA, respectively. The diagnosis of type 1 diabetes mellitus using the RIA and ELISA methods showed substantial agreement with the kappa values of 0.74 for all participants, and of 0.64 for the acute type; however, there was moderate agreement with the kappa value of 0.56 for the slowly progressive type.
  
  
  CONCLUSIONS
  The present study suggests that both anti-glutamic acid decarboxylase antibody by RIA and ELISA was useful for diagnosing type 1 diabetes mellitus. However, in the slowly progressive type, the degree of agreement of these two kits was poorer compared with those in all participants or in the acute type.
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Takashi
authors.identifier: http://orcid.org/0000-0001-8634-9657
authors.initials: T
authors.lastname: Murata
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Kokoro
authors.initials: K
authors.lastname: Tsuzaki
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Nirengi
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Mizutani
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Hayami
authors.initials: H
authors.lastname: Okada
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Tsukamoto
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Odori
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Nakagawachi
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Yaeko
authors.initials: Y
authors.lastname: Kawaguchi
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Fumi
authors.initials: F
authors.lastname: Yoshioka
authors.affiliation: Diabetes Center, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yamada
authors.affiliation: Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Shimatsu
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kotani
authors.affiliation: Department of Endocrinology, Metabolism, and Hypertension, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Satoh-Asahara
authors.affiliation: Division of Preventive Medicine, Clinical Research Institute, National Hospital Organization Kyoto Medical Center, Kyoto, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Sakane
mesh_terms: D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay
chemical_list: D005968:Glutamate Decarboxylase
keywords: Anti-glutamic acid decarboxylase antibody; Enzyme-linked immunosorbent assay; Type 1 diabetes mellitus