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Enzyme linked immunosorbent assays (ELISA) for the qualitative detection of IgA anti-gliadin antibodies in human serum to aid in the diagnosis of patients with celiac disease or dermatitis herpetiformis in conjunction with other laboratory and clinical findings

Enzyme linked immunosorbent assays (ELISA) for the qualitative detection of IgG anti-gliadin antibodies in human serum to aid in the diagnosis of patients with celiac disease or dermatitis herpetiformis in conjunction with other laboratory and clinical findings

This test is performed as a solid phase immunoassay. Microwells are coated with antigen. Controls, calibrators and patient sera are incubated in the antigen coated wells to allow specific antibodies present in the serum to bind to the gliadin antigen. Bound antibodies are detected by adding an enzyme labeled anti-human IgA or IgG conjugate. Specific enzyme substrate (TMB) is then added and the presence of antibodies is detected by a color change that is read by a spectrophotometer at 450 mm. Results are expressed in ELISA units per milliliter (EU/ml) and reported as positive or negative.

Here's a breakdown of the acceptance criteria and study findings for the Immulisa Enhanced Gliadin IgA Antibody ELISA and Immulisa Enhanced Gliadin IgG Antibody ELISA, based on the provided document:

Acceptance Criteria and Reported Device Performance

The document describes several non-clinical and clinical tests. However, explicit "acceptance criteria" in the form of pre-defined thresholds for performance metrics (like minimum sensitivity/specificity) are not explicitly stated within the provided text for the new Immulisa Enhanced Gliadin assays. Instead, the study presents the performance of the new devices in comparison to existing predicate devices and against a set of characterized clinical samples. The "acceptance" is implied by demonstrating substantial equivalence and satisfactory performance in these various tests.

I've organized the reported performance for the new devices based on the test sections:

Table 1: Device Performance Summary

Study Details

Here's the detailed information regarding the studies:

1. Sample size used for the test set and the data provenance:

   • Method Comparison (Vs Predicate):
     • IgA test set: 400 samples (109 Positive, 291 Negative by predicate).
     • IgG test set: 459 samples (205 Positive, 254 Negative by predicate).
     • These samples appear to be clinical samples ("well-characterized CD and DH subjects and disease controls").
     • Data Provenance: Not explicitly stated, but based on the overall document (Immco Diagnostics, Buffalo, NY), it's likely from the US or procured for use in the US. The terms "well-characterized" suggest retrospective collection.
   • Cross-Reactivity Study:
     • Test set: 456 sera from individuals with other potentially cross-reactive autoimmune and infectious disorders.
     • Data Provenance: Not explicitly stated, but likely retrospective clinical samples.
   • Clinical Study:
     • Test set: 250 celiac disease samples, 45 dermatitis herpetiformis samples, and 456 autoimmune and infectious disease controls. IgA deficient CD patients were excluded from these calculations.
     • Data Provenance: Not explicitly stated, but likely retrospective clinical samples.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • The document implies ground truth was established by "well-characterized CD and DH subjects and disease controls" and "clinical samples." It also directly compares the new device to existing predicate devices.
   • However, the specific number and qualifications of experts (e.g., "radiologist with 10 years of experience") used to establish the ultimate ground truth for the patient classifications (celiac, DH, healthy, specific autoimmune diseases) are not mentioned in the provided text. It's typical for such characterization to involve clinical diagnosis based on a combination of endoscopy, biopsy, serology, and clinical presentation, but the specific expert involvement is not detailed.

3. Adjudication method for the test set:

   • Not applicable / Not specified. The document describes laboratory studies comparing results to predicate devices and clinical diagnoses, rather than human reader interpretation that would require adjudication.

4. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • No, an MRMC comparative effectiveness study was not done. This device is an in-vitro diagnostic (IVD) assay, not an AI-assisted diagnostic imaging or interpretation tool for human readers. Therefore, this type of study is not relevant.

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

   • Yes, this is a standalone performance study. The device itself is an automated ELISA system. The performance metrics (sensitivity, specificity, agreement, precision, etc.) represent the performance of the assay (the "algorithm"/test process) without human interpretive intervention beyond running the test and reading the output. The interpretation of the ELISA results (positive/negative/borderline) is inherent to the device's design.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • For the "Method Comparison" studies against the predicate devices, the predicate device's result itself acts as a form of "ground truth" for comparison purposes.
   • For the "Clinical Study" and "Cross-Reactivity" studies, the ground truth for celiac disease, dermatitis herpetiformis, and the various autoimmune/infectious diseases was based on the "well-characterized" nature of the samples. This typically implies a clinical diagnosis (likely involving expert consensus from physicians, pathology results from biopsies, and other diagnostic tests). The document does not provide the specific modalities (e.g., gold standard biopsy results for all celiac cases) used for this characterization for each individual sample, but generally, for celiac disease, this would involve small intestinal biopsy as a definitive diagnostic tool.

7. The sample size for the training set:

   • Not applicable / Not specified. This document describes the performance of an ELISA assay, which is a biochemical test, not a machine learning or AI algorithm that undergoes "training." The results presented are from validation and clinical evaluation studies of the developed assay.

8. How the ground truth for the training set was established:

   • Not applicable. As this is not an AI/ML algorithm requiring a training set, the concept of establishing ground truth for such a set is irrelevant in this context.

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