This multicenter, blinded, cross-sectional study aims to evaluate the clinical performance of a novel DAB chromogenic tissue-based assay (TBA) for detecting anti-GABAB receptor (anti-GABABR) antibodies. A total of 300 participants will be enrolled across four groups: (a) 50 patients with anti-GABABR antibody-positive encephalitis; (b) 100 patients with suspected autoimmune encephalitis and negative anti-neuronal antibody cell-based assay (CBA); (c) 50 patients with non-autoimmune disease (Alzheimer's disease); and (d) 100 patients with anti-NMDAR antibody-positive encephalitis. Residual serum and cerebrospinal fluid samples will be tested using the optimized DAB-TBA. Discordant results between CBA and DAB-TBA will be adjudicated by an independent panel using confirmatory methods (immunoblot, repeat CBA, and clinical follow-up), and inter-reader agreement will be reported. The sensitivity, specificity, and ROC curve of the assay will be evaluated against the reference standard.
None
Residual serum or CSF volume insufficient for DAB-TBA and confirmatory testing.
Sample quality unacceptable (gross hemolysis, lipemia, contamination, or clot).
Freeze-thaw cycles exceeding the predefined limit (specify N).
Key clinical information (final diagnosis, CBA result, or demographic data) unavailable or incomplete.
Patients aged 14-85 years recruited from neurology departments across participating centers, grouped as: (a) anti-GABABR antibody-positive encephalitis; (b) suspected autoimmune encephalitis with negative anti-neuronal antibody CBA; (c) non-autoimmune disease (Alzheimer's disease); (d) anti-NMDAR antibody-positive encephalitis.
Case-only
Cross-sectional
Not listed
Sensitivity of novel DAB chromogenic TBA for detection of anti-GABABR antibodies
Sensitivity of the novel DAB chromogenic tissue-based assay (TBA) for detecting anti-GABABR antibodies, calculated as true positive / (true positive + false negative), using CBA results as the reference standard.
Specificity of the novel DAB chromogenic TBA for detection of anti-GABABR antibodies
Specificity of the novel DAB chromogenic tissue-based assay (TBA) for detecting anti-GABABR antibodies, calculated as true negative / (true negative + false positive), using CBA results as the reference standard.
Area under the ROC curve (AUC) of DAB chromogenic TBA for anti-GABABR antibody detection
ROC curve and AUC value of the novel DAB chromogenic TBA for anti-GABABR antibody detection with CBA as reference standard.
Cohen's kappa coefficient between DAB-TBA and CBA reference method
Concordance between the novel DAB chromogenic TBA and the CBA reference method for anti-GABABR antibody detection, quantified by Cohen's kappa coefficient.
Agreement between serum and CSF detection results by DAB-TBA
Concordance of DAB chromogenic TBA results between paired serum and CSF samples, expressed as agreement percentage and Cohen's kappa.
Subgroup detection performance of DAB-TBA
Sensitivity and specificity of the DAB chromogenic TBA stratified by the four predefined subgroups (anti-GABABR-positive encephalitis, CBA-negative suspected autoimmune encephalitis, non-autoimmune neurological disease, and anti-NMDAR encephalitis).
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Third Affiliated Hospital, Sun Yat-Sen University
Lead sponsor
Guangzhou KingMed Center for Clinical Lab.Co., Ltd
Collaborator
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