(73 days)
A latex agglutination assay intended for the quantitative turbidimetric detection of Rheumatoid IgM antibodies in human serum and plasma. When used according to instructions, the assay is useful in establishing the presence of rheurmatoid factor and as an aid in the diagnosis and management of rheumatoid arthritis.
Raichem's Rheumatoid Factor SPIA ™ latex agglutination assay is a quantitative turbidimetric assay for the detection of Rheumatoid Factor IgM antibodies in human serum and plasma. In this assay, latex microspheres coated with human and rabbit IgG are diluted in a medium, usually, designed to allow aggregation without rapid settling of Rheumatoid Factor complexed microparticles. As aggregates form, the suspension becomes less cloudy, resulting in less light being absorbed. The change in optical density is proportional to the amount of RF present in the suspension. A quantitative determination of the amount of RF present in a serum/plasma sample is made by comparison to a standard curve.
This document describes a diagnostic device, the Raichem's Rheumatoid Factor SPIA™ latex agglutination assay, for detecting Rheumatoid Factor IgM antibodies.
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1. Table of Acceptance Criteria & Reported Device Performance
The document does not explicitly state "acceptance criteria" as pass/fail thresholds for performance metrics. However, it presents
the performance of the proposed device in comparison to a predicate device and an automated method. We can infer that the reported percentages and confidence intervals for sensitivity and specificity are intended to demonstrate acceptable performance.
| Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Relative Analytical Sensitivity | High correlation with predicate | 95.4% (0.95 CI: 90.8% to 97.8%) |
| Relative Analytical Specificity | High correlation with predicate | 100% (0.95 CI: 98.0% to 100%) |
| Inter-assay Precision (%CV) | (Not explicitly stated) | Range: 5.3% - 20.7% (for Mean IU/mL) |
| Intra-assay Precision (%CV) | (Not explicitly stated) | Range: 5.4% - 11.5% (for Mean IU/mL) |
2. Sample Size Used for the Test Set and Data Provenance
- Test Set Sample Size: 335 serum specimens (for the comparison study with the predicate device and automated method).
- Data Provenance: The data comes from "serum specimens from rheumatoid arthritis patients, patients with autoimmune diseases, and normal apparently healthy donors." The country of origin is not specified, but the context implies it is a clinical study. The data appears to be retrospective as it involves existing banked or collected specimens.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document mentions "The discrepant and equivocal samples were evaluated by a third party EIA method." This implies that a reference method (EIA) was used to resolve discrepancies and establish a final ground truth for specific cases. However, it does not specify the number of experts or their qualifications. It's likely that the "third party EIA method" itself is considered the expert or reference standard, rather than a human expert.
4. Adjudication Method for the Test Set
The adjudication method is described as: "The discrepant and equivocal samples were evaluated by a third party EIA method." This suggests a method where discrepant results (between the proposed device and the predicate) and equivocal results (from the predicate device) were adjudicated by a recognized reference assay. This is a form of third-party adjudication by a reference method.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is a quantitative turbidimetric assay, not an imaging device or one that relies on human interpretation in the same way an MRMC study would assess. Its performance is measured directly against a predicate device and automated systems, not human readers with and without AI assistance.
6. Standalone Performance (Algorithm Only Without Human-in-the-Loop Performance)
Yes, the performance data provided appears to be for the standalone (algorithm only) performance of the Raichem's Rheumatoid Factor SPIA™ assay. The assay is described as a "quantitative turbidimetric assay" which, while designed to be adaptable to automated systems like the COBAS-MIRA, fundamentally operates based on a direct measurement of optical density change. The precision and comparison studies detail the analytical performance of the assay itself, not its performance when interpreted by a human in a loop.
7. Type of Ground Truth Used
The primary ground truth appears to be based on results from a predicate device (Hemagen® RF Kit (HA method)) and a third-party EIA method used for resolving discrepancies. In essence, it's a reference standard comparison. The predicate device itself acts as a clinical reference. Additionally, the calibrator verification mentions comparison to the World Health Organization International Reference Preparation of Rheumatoid Arthritis Serum, which serves as a highly reliable reference for calibrator accuracy.
8. Sample Size for the Training Set
The document does not explicitly mention a separate "training set" sample size. This is typical for in vitro diagnostic (IVD) assays like this one, which are often developed using established biochemical principles and then validated on independent test sets (as described in section 2). The development of the assay itself, including optimization of reagents and protocols, would involve internal testing, but a formal "training set" in the machine learning sense is not applicable or reported here.
9. How the Ground Truth for the Training Set Was Established
As no explicit "training set" is mentioned, the method for establishing its ground truth is not applicable/not provided in this summary. The ground truth for the validation/test set was established through comparison with a predicate device and adjudication by a third-party EIA method.
§ 866.5775 Rheumatoid factor immunological test system.
(a)
Identification. A rheumatoid factor immunological test system is a device that consists of the reagents used to measure by immunochemical techniques the rheumatoid factor (antibodies to immunoglobulins) in serum, other body fluids, and tissues. Measurement of rheumatoid factor may aid in the diagnosis of rheumatoid arthritis.(b)
Classification. Class II (performance standards).