(34 days)
The Stellar Bio Systems' Indirect Fluorescence Assay (IFA) for Anti-native DNA (nDNA) IgG Antibody is intended for the qualitative and semi-quantitative detection of IgG (Immunoglobulin G) antibody to nDNA in human serum. Detection of nDNA IgG antibody in humans can be used as an aid in the diagnosis of systemic lupus erythematosus (SLE).
The nDNA IgG IFA is an Indirect Fluorescence Assay (IFA) for the detection of IgG antibodies to nDNA antigen in human serum.
The provided document describes the performance characteristics of the "Indirect Fluorescence Assay for Anti-native DNA (nDNA) IgG Antibody" device.
Here's an analysis of the acceptance criteria and the study that proves the device meets them:
1. A table of acceptance criteria and the reported device performance:
The document doesn't explicitly state "acceptance criteria" in a separate section. However, the "Performance Characteristics" section provides data comparing the new device against an "Alternate IFA" (a commercially available nDNA IFA), implying these comparative metrics serve as the basis for acceptance. The performance is reported in terms of relative sensitivity, relative specificity, and relative agreement.
| Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Relative Sensitivity | High agreement with predicate | 96.2% |
| Relative Specificity | High agreement with predicate | 99.2% |
| Relative Agreement | High agreement with predicate | 98.7% |
| Titer Agreement (Identical) | High agreement with predicate | 11/20 (55%) |
| Titer Agreement (± 1 dilution) | High agreement with predicate | 7/20 (35%) |
| Titer Agreement (± 2 dilutions) | Not specified, but reported | 2/20 (10%) |
| Reproducibility (Identical) | Not specified, but reported, implied high agreement | 31/36 (86.1%) |
| Reproducibility (± 1 dilution) | Not specified, but reported, implied high agreement | 5/36 (13.9%) |
2. Sample size used for the test set and the data provenance:
- Sample Size for Test Set: 149 sera for relative sensitivity/specificity/agreement. 20 positive sera for titer agreement. 4 sera (3 positive, 1 negative) evaluated for reproducibility, with serial dilutions and multiple assays resulting in 36 data points.
- Data Provenance: "The samples were frozen retrospective relative to a commonly treated population of patients diagnosed with SLE." The sera were "gender, and geographical areas," implying a diverse, though unspecified, geographical origin. It's explicitly stated that there was not an attempt to correlate the assay's results with disease presence or absence, and "No judgment can be made on the comparison assay's accuracy to predict disease." This means the study is a comparison to a predicate, not a clinical diagnostic performance study against a true disease gold standard.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Number of experts: Not applicable. The "ground truth" for the test set was established by the "Alternate IFA" (a commercially available nDNA IFA), not by human experts. The study directly compares the new device's results to the predicate device's results.
- Qualifications of experts: Not applicable.
4. Adjudication method for the test set:
- Not applicable, as the "ground truth" was derived from a predicate device's results, not human interpretation requiring adjudication.
5. 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:
- Not applicable. This is an in vitro diagnostic (IVD) device for laboratory testing, not an AI-assisted diagnostic imaging or interpretation tool for human readers. There are no human readers or AI involved in the interpretation of results as per the described device operation.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
- Yes, this study is inherently a standalone performance evaluation of the device itself. The device (IFA for nDNA IgG antibody) is an in vitro diagnostic test. Its performance is measured based on its direct output (positive/negative, titer) in comparison to a predicate device. There is no human-in-the-loop component described for its operation or interpretation.
7. The type of ground truth used:
- Reference standard/Predicate device result: The "ground truth" for this study was the results obtained from a "commercially available nDNA IFA" (the Alternate IFA). The study explicitly states, "Please be advised that 'relative' refers to the comparison of this assay's results to that of a similar assay. There was not an attempt to correlate the assay's results with disease presence or absence. No judgment can be made on the comparison assay's accuracy to predict disease."
8. The sample size for the training set:
- Not applicable. This is a traditional IVD device, not a machine learning or AI algorithm that requires a training set.
9. How the ground truth for the training set was established:
- Not applicable, as there is no training set for this type of device.
§ 866.5100 Antinuclear antibody immunological test system.
(a)
Identification. An antinuclear antibody immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the autoimmune antibodies in serum, other body fluids, and tissues that react with cellular nuclear constituents (molecules present in the nucleus of a cell, such as ribonucleic acid, deoxyribonucleic acid, or nuclear proteins). The measurements aid in the diagnosis of systemic lupus erythematosus (a multisystem autoimmune disease in which antibodies attack the victim's own tissues), hepatitis (a liver disease), rheumatoid arthritis, Sjögren's syndrome (arthritis with inflammation of the eye, eyelid, and salivary glands), and systemic sclerosis (chronic hardening and shrinking of many body tissues).(b)
Classification. Class II (performance standards).