(263 days)
This test system is for in vitro diagnostic use for the detection of antinuclear antibodies in human serum, with specific identification of autoantibodies to the SS-A/Ro antigen. This test system is to be used as an aid in the detection of antibodies associated with systemic rheumatic disease. The results from this assay can be used as an aid in the diagnosis of autoimune diseases.
This is an indirect fluorescent antibody test for the semi-quantitative detection of antinuclear antibody in human serum. The transfected HEP-2 cell line allows for the identification of anti-SS-A/Ro antibodies because of the unique staining pattern that these antibodies show on this cell line.
Here's an analysis of the provided text, outlining the acceptance criteria and study details for the HEp-2000® Fluorescent ANA-Ro Test System:
Acceptance Criteria and Device Performance Study
The provided text describes a submission for a new device, the HEp-2000® Fluorescent ANA-Ro Test System, seeking substantial equivalence to a legally marketed device (RELISA® SS-A/SS-B Antibody Test System, K955603). The study focuses on demonstrating the unique ability of the HEp-2000® cell line to specifically identify anti-SS-A/Ro antibodies and confirming the presence of SS-A/Ro antibodies.
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied through the comparisons to existing HEp-2 cells and ELISA testing, specifically highlighting the ability to identify SS-A/Ro antibodies distinctly.
| Acceptance Criteria (Implied) | Reported Device Performance (HEp-2000® Fluorescent ANA-Ro Test System) |
|---|---|
| Normal Samples: | Normal Samples (500 healthy blood donors): |
| - Low false positive rate for ANA | - 36 samples (7.2%) showed positive ANA reactions at 1:40 dilution. |
| - Consistent patterns with non-transfected HEp-2 where applicable. | - Patterns identical on both substrates for 34 of 36 positives. |
| - Identify SS-A/Ro in true SS-A/Ro positive samples even if non-transfected HEp-2 is negative/weak. | - Two discrepant samples (both SS-A/Ro confirmed by ELISA and Western blot): One showed weak fine speckled on non-transfected HEp-2 but typical "SS-A/Ro" staining on HEp-2000®. The other was negative on non-transfected HEp-2 but showed typical "SS-A/Ro" staining on HEp-2000®. |
| Sera with only Ro/SS-A Antibodies: | Sera from 46 patients with only Ro/SS-A antibodies: |
| - High sensitivity for SS-A/Ro antibodies | - All 46 (100%) were positive (distinctive Ro/SS-A staining pattern) with HEp-2000®. |
| - Superior performance to non-transfected HEp-2 for SS-A/Ro detection. | - 36 (78%) were positive (speckled pattern) with non-transfected HEp-2 cells. |
| Sera with other Autoantibodies: | Sera from 230 patients with various rheumatic/non-rheumatic diseases: |
| - Consistent patterns for non-SS-A/Ro antibodies. | - 333 staining patterns were identical on both substrates (single or mixed patterns). |
| - Accurate identification of SS-A/Ro antibodies even in complex samples. | - 29 samples showed distinctive "SS-A/Ro" staining pattern on HEp-2000®. 23 had speckled patterns on non-transfected HEp-2. The 6 discrepant samples (positive on HEp-2000®, negative on non-transfected HEp-2) all had SS-A/Ro antibodies confirmed by distinctive pattern, ELISA, and Western blot. |
| Titer Comparisons: | Titer Comparisons: |
| - Higher titers for SS-A/Ro on HEp-2000® (due to overexpression). | - Samples with anti-Ro/SS-A antibodies show higher titer values on HEp-2000® than on non-transfected HEp-2. |
| - No significant titer differences for other autoantibodies. | - Sera with other autoantibody specificities do not show significant titer differences. |
| Titer Reproducibility: | Titer Reproducibility (10 samples, 3 lots, 3 occasions): |
| - Consistent results across lots and runs. | - No negative sample showed positive results. All titer values within one two-fold dilution of established mean. |
| Confirmation of SS-A/Ro Antibodies: | Confirmation of SS-A/Ro Antibodies (349 known ANA positive samples): |
| - High positive predictive value for distinctive SS-A/Ro pattern. | - Of 239 samples with distinctive SS-A/Ro staining pattern, 238 (99.6%) had positive ELISA tests for SS-A/Ro antibodies. |
| - Absence of distinctive pattern does not rule out SS-A/Ro. | - An additional 79 samples with other patterns (speckled/homogeneous) gave positive ELISA tests for SS-A/Ro antibodies. |
2. Sample Size Used for the Test Set and Data Provenance
The "test set" in this context refers to the samples used to demonstrate the device's performance against the described criteria, likely corresponding to a validation or clinical study set.
- Sample Sizes:
- Normal Samples: 500 healthy blood donors (242 females, 258 males).
- Sera from Patients with Only Ro/SS-A Antibodies: 46 patients with SLE or Sjögren's Syndrome.
- Sera from Patients with Autoantibodies Other Than SS-A/Ro: 230 patients with a variety of rheumatic and non-rheumatic diseases.
- Titer Reproducibility: 10 samples (CDC controls and in-house sera).
- Confirmation of SS-A/Ro Antibodies: 349 patients with known positive ANA tests (from a large rheumatology reference laboratory).
- Total SS-A/Ro containing sera examined across studies: 429 sera.
- Data Provenance: The document does not explicitly state the country of origin. The mention of "CDC controls" (Centers for Disease Control and Prevention) suggests a US origin or at least use of US-standardized materials. Given the FDA submission, it's highly likely the studies were conducted in or accepted by the US regulatory framework. The data is retrospective, as it involves analyzing existing sera.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number or qualifications of experts used for establishing ground truth, such as interpreting the HEp-2 or HEp-2000 staining patterns. It implies that these interpretations were done by qualified laboratory personnel following established protocols for fluorescent antibody tests. However, the ground truth for the presence of SS-A/Ro antibodies was established through objective methods.
4. Adjudication Method for the Test Set
The document does not explicitly describe a formal adjudication method (like 2+1 or 3+1 consensus) for the interpretation of fluorescent patterns. The interpretation appears to be based on standard laboratory practice, with discrepancies or confirmations being resolved by "ELISA testing and by Western immunoblotting." This suggests a hierarchical approach rather than a consensus among multiple human readers for pattern interpretation.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a MRMC comparative effectiveness study was not explicitly described. The study compares the performance of the new device (HEp-2000®) against an older method (non-transfected HEp-2 cells) and a predicate ELISA device, but it doesn't involve multiple human readers interpreting cases with and without AI assistance to measure reader improvement. The "device" in this context is primarily an improved assay, not an AI-powered interpretation tool for human readers.
6. Standalone Performance Study
Yes, a standalone performance study was implicitly done. The entire submission describes the performance of the "HEp-2000® Fluorescent ANA-Ro Test System" (the algorithm/device) on its own, independent of human interpretation improvements (as it's a diagnostic test providing a result rather than an interpretative aid). The results presented are the direct output of the test system, compared to ground truth methods.
7. Type of Ground Truth Used
The ground truth for the presence or absence of SS-A/Ro antibodies was established by objective, highly specific laboratory methods:
- ELISA testing (Predicate Device): RELISA® SS-A/SS-B Antibody Test System (K955603)
- Western immunoblotting
For the patterns observed on HEp-2 and HEp-2000 cells, the ground truth is established by the accepted morphological characteristics of these patterns, which implicitly relies on expert consensus in the field for what constitutes a "speckled pattern" or "typical SS-A/Ro staining." However, when a discrepancy arose or confirmation was needed, the more objective ELISA and Western blot results trumped the pattern interpretation for confirming SS-A/Ro antibody presence.
8. Sample Size for the Training Set
The document does not specify a separate "training set" or its sample size. The entire dataset described appears to be used for validation and demonstration of performance. This is typical for a 510(k) submission for an in-vitro diagnostic assay improvement, where the "training" (development) of the cell line happened prior to these validation studies.
9. How the Ground Truth for the Training Set Was Established
Since a separate "training set" is not detailed, the method for establishing ground truth for any underlying development of the HEp-2000® cell line is not described in this document. It can be inferred that the development of the transfected cell line was guided by scientific understanding of SS-A/Ro autoantigen expression and its visual manifestation in IF (Immunofluorescence) assays, likely confirmed by similar biochemical and immune-assay methods as used in the validation steps (e.g., ELISA, Western Blot, molecular characterization of the transfection).
§ 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).