(104 days)
The assay is to be used to detect antibodies in a single serum specimen. The results of the assay are to be used as an aid to the diagnosis of Wegener's granulomatosis. FOR IN VITRO DIAGNOSTIC USE.
The PR-3 ELISA test is an enzyme-linked immunosorbent assay (ELISA) for the detection and semi-quantitation of antibodies to Proteinase-3 in human sera. The PR-3 ELISA test is an enzyme linked immunosorbent assay to detect IgG, IgM, and IgA antibodies to Proteinase-3. Purified PR-3 is attached to a solid phase microtiter well. Diluted test sera is added to each well. If the antibodies are present that recognize the antigen they will bind to the antigen in the well. After incubation the wells are washed to remove unbound antibody. An enzyme labeled anti-human IgG, M, A is added to each well. If antibody is present it will bind to the antibody attached to the antigen on the well. After incubation the wells are washed to remove unbound conjugate. A substrate solution is added to each well If enzyme is present the substrate will undergo a color change. After an incubation period the reaction is stopped and the color intensity is measured photometrically, producing an indirect measurement of specific antibody in the patient specimen.
Acceptance Criteria and Device Performance for PR-3 ELISA Test Kit
This document describes the acceptance criteria and a detailed study supporting the performance of the PR-3 ELISA test kit for the detection and semi-quantitation of antibodies to Proteinase-3 in human sera.
I. Acceptance Criteria and Reported Device Performance
The acceptance criteria for the PR-3 ELISA test kit are derived from its stated intended use as an aid in the diagnosis of Wegener's granulomatosis and its substantial equivalence to IFA (Indirect Immunofluorescence Assay). The study primarily focuses on demonstrating the analytical performance (sensitivity, specificity, precision, linearity, and cross-reactivity) of the device.
| Performance Metric | Acceptance Criteria (Implicit/Explicit from Predicate Comparison) | Reported Device Performance (PR-3 ELISA) |
|---|---|---|
| Relative Sensitivity (vs. IFA) | High sensitivity, comparable to IFA for ANCA related to PR-3. | 98.2% (95% CI: 94.5 - 100%) |
| Relative Specificity (vs. IFA) | High specificity, comparable to IFA. | 95.6% (95% CI: 92.5 - 98.6%) |
| Relative Agreement (vs. IFA) | High agreement with IFA. | 96.2% (95% CI: 93.7 - 98.7%) |
| Relative Sensitivity (vs. Alternate ELISA) | High sensitivity, comparable to an existing ELISA device. | 92.1% (95% CI: 85.3 - 98.9%) |
| Relative Specificity (vs. Alternate ELISA) | High specificity, comparable to an existing ELISA device. | 98.8% (95% CI: 97.0 - 1.00%) |
| Relative Agreement (vs. Alternate ELISA) | High agreement with an existing ELISA device. | 98.9% (95% CI: 94.5 - 99.2%) |
| Clinical Sensitivity (Wegener's) | High sensitivity for Wegener's granulomatosis. | 97.5% (95% CI: 92.6 - 100%) |
| Clinical Sensitivity (Microscopic Polyangiitis) | (No explicit criterion, but reported for information) | 55.0% (95% CI: 39.3 - 70.7%) |
| Clinical Specificity (Other Autoimmune Sera) | High specificity (low cross-reactivity) for other autoimmune conditions. | 100% (95% CI: 85.9 - 100%) |
| Clinical Specificity (Normals) | High specificity for normal individuals. | 100% (95% CI: 98.1 - 100%) |
| Precision (Coefficient of Variation - C.V.) | C.V.'s of less than 15% with proper technique. | Achieved for majority of tested sera. Range 1.95% - 84.50% (see Table 4) |
| Linearity (r value) | Linear relationship with serum dilution (high correlation coefficient). | ≥ 0.984 for all tested sera. |
| Cross-Reactivity | No significant cross-reactivity with common autoantibodies. | All tested sera with other autoantibodies interpreted as negative. |
II. Sample Size and Data Provenance for the Test Set
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Sample Size for Sensitivity and Specificity (relative to IFA):
- Patient with Wegener's granulomatosis/microscopic polyangiitis (IFA Positive): 54 sera
- Normals and other patients (IFA Negative): 181 sera
- Total: 235 sera
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Sample Size for Sensitivity and Specificity (relative to Alternate ELISA):
- Total: 235 sera (same group as for IFA comparison)
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Sample Size for Clinical Sensitivity and Specificity:
- Wegener's granulomatosis: 40 sera
- Microscopic polyangiitis: 40 sera
- Other autoimmune sera: 21 sera (containing antibodies to Ro, La, Sm, RNP, Jo-1, Scl-70, dsDNA)
- Normals: 155 sera
- Total: 256 sera
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Sample Size for Precision: 9 different sera, each tested 10 times on 3 different assays (total 270 measurements).
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Sample Size for Linearity: 5 positive sera, serially diluted twofold.
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Sample Size for Cross-reactivity: 21 sera containing antibodies to potentially cross-reactive antigens (Ro, La, Sm, RNP, Jo-1, Scl-70, dsDNA).
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Data Provenance: The document does not explicitly state the country of origin. The data appears to be retrospective, as patient sera were "from patients diagnosed with" specific conditions, implying collection prior to the study.
III. Number of Experts and Qualifications for Ground Truth
- The document does not mention the number of experts used or their specific qualifications (e.g., radiologist with 10 years of experience).
- The ground truth for IFA results (used as a comparator for relative sensitivity/specificity) is implicitly established by the performance of the IFA assay itself, which is a predicate device.
- The ground truth for patient diagnoses (Wegener's granulomatosis, microscopic polyangiitis) and the presence of other autoimmune conditions/antibodies are stated as prior diagnoses, but the process of establishing these diagnoses by experts is not detailed within this document.
IV. Adjudication Method for the Test Set
- No explicit adjudication method is described for the test set. The study relies on pre-existing diagnoses and comparator assay results (IFA, alternate ELISA) as the ground truth.
V. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No MRMC comparative effectiveness study was done. This study evaluates an in vitro diagnostic (IVD) device, which typically assesses the analytical and clinical performance of the assay itself rather than the improvement of human reader performance with AI assistance. The device is a laboratory test, not an AI interpretation tool for human readers.
VI. Standalone (Algorithm Only) Performance
- Yes, a standalone performance study was done. The entire study analyzes the performance of the PR-3 ELISA kit (the algorithm/device) in isolation, without human intervention in the interpretation of the raw assay data (though human technical skill is involved in performing the assay). The reported sensitivities, specificities, precision, and linearity are all measures of the device's standalone performance.
VII. Type of Ground Truth Used
- Comparator Assay Results: For relative sensitivity and specificity, the ground truth was established by the results of the Indirect Immunofluorescence Assay (IFA) for ANCA and an alternate legally marketed ELISA device.
- Clinical Diagnosis: For clinical sensitivity and specificity, the ground truth was based on patient diagnoses of Wegener's granulomatosis and microscopic polyangiitis, as well as the presence of other autoimmune conditions/antibodies (e.g., Ro, La, Sm, RNP, Jo-1, Scl-70, dsDNA) and serological status of normals.
VIII. Sample Size for the Training Set
- The document does not specify a training set sample size. As this is a traditional ELISA assay and not a machine learning or AI algorithm in the modern sense, the concept of a "training set" for model development as typically understood in AI/ML is not directly applicable. The device's parameters (e.g., cutoff values) would have been established during earlier development and validation phases, but these details are not provided here.
IX. How Ground Truth for the Training Set Was Established
- Given that this is a conventional immunoassay, the concept of a distinct "training set" with ground truth in the AI/ML context isn't relevant. The "ground truth" for establishing assay parameters (like cutoff values) would typically involve internal studies using well-characterized clinical samples and comparison against reference methods (like IFA) to optimize performance, but the specifics of this process are not described in this summary.
§ 866.5660 Multiple autoantibodies immunological test system.
(a)
Identification. A multiple autoantibodies immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoantibodies (antibodies produced against the body's own tissues) in serum and other body fluids. Measurement of multiple autoantibodies aids in the diagnosis of autoimmune disorders (disease produced when the body's own tissues are injured by autoantibodies).(b)
Classification. Class II (performance standards).