(260 days)
QUANTA Flash® Scl-70 is a chemiluminescent immunoassay for the semi-quantitative determination of IgG anti-Scl-70 autoantibodies in human serum. The presence of anti-Scl-70 autoantibodies, in conjunction with clinical findings and other laboratory tests, aids in the diagnosis of systemic sclerosis.
QUANTA Flash® Scl-70 Calibrators are intended for use with the QUANTA Flash® Scl-70 chemiluminescent immunoassay for the determination of IgG anti-Scl-70 autoantibodies in human serum. Each calibrator establishes a point of reference for the working curve that is used to calculate unit values.
QUANTA Flash® Scl-70 Controls are intended for use with the OUANTA Flash® Scl-70 chemiluminescent immunoassay for quality control in the determination of IgG anti-Scl-70 autoantibodies in human serum.
The QUANTA Flash Scl-70 assay is designed to run on the BIO-FLASH® instrument. This platform is a fully automated closed system with continuous load and random access capabilities that automatically processes the samples, runs the assay and reports the results. It includes liquid handling hardware, luminometer and computer with software-user interface. The QUANTA Flash Scl-70 assay utilizes a reagent cartridge format, which is compatible with the BIO-FLASH instrument.
Recombinant Scl-70 is coated onto paramagnetic beads. The bead suspension is lyophilized and stored in the bead tube. Prior to use in the BIO-FLASH system, the sealed reagent tubes are pierced with the reagent cartridge lid and the beads are rehydrated and resuspended using resuspension buffer by pipetting up and down with a transfer pipette. The reagent cartridge is then loaded onto the BIO-FLASH instrument. Samples are also loaded onto the instrument in sample racks. A patient serum sample is prediluted 1:23.5 by the BIO-FLASH with system rinse in a disposable plastic cuvette. Small amounts of the diluted patient serum, the beads, and assay buffer are all combined into a second cuvette, and mixed. This cuvette is then incubated at 37°C. The beads are magnetized and washed several times. Isoluminol conjugated anti-human IgG antibodies are then added to the cuvette, and again incubated at 37°C. The beads are magnetized and washed repeatedly. The isoluminol conjugate is oxidized when Trigger 1 (Fe(III) coproporphyrin in sodium hydroxide solution) and Trigger 2 (urea-hydrogen peroxide in sodium chloride solution) are added to the cuvette, and the flash of light produced from this reaction is measured as Relative Light Units (RLU) by the BIO-FLASH optical system. The RLU are proportional to the amount of isoluminol conjugate that is bound to the human IgG, which is in turn proportional to the amount of anti-Scl-70 antibodies bound to the corresponding Scl-70 on the beads.
For quantitation, the QUANTA Flash Scl-70 assay utilizes a predefined lot specific Master Curve that is uploaded onto the instrument through the reagent cartridge barcode. Every new lot number of reagent cartridge must be calibrated before first use, with the QUANTA Flash Scl-70 Calibrators. Based on the results obtained with the two Calibrators included in the Calibrator Set (sold separately), an instrument specific Working Curve is created, which is used to calculate chemiluminescent units (CU)mL from the instrument signal (RLU) obtained for each sample.
Here's a summary of the acceptance criteria and study findings based on the provided text, structured as requested:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Characteristic | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Precision | Total %CV values within 10%. | All total %CV values for 13 samples across various concentrations were within 10%. (Range: 3.4% - 5.9%) |
| Reproducibility (Between sites) | All %CV values within 15%. | All %CV values for 8 samples across three sites were within 15%. (Range: 1.3% - 8.3%) |
| Reproducibility (Between lots) | All %CV values within 10%. | All %CV values for 8 samples across three different lots were within 10%. (Range: 1.5% - 9.6%) |
| Limit of Quantitation (LoQ) | Total error (TE) X%). However, the comparison aimed to show substantial equivalence. | Total Agreement: 97.6% (95% CI: 95.9% – 98.6%) for all 539 samples. |
| Agreement within AMR (193 samples): Negative Agreement = 93.3% (95% CI: 88.1% – 96.3%), Positive Agreement = 95.5% (95% CI: 84.9% – 98.7%), Total Agreement = 93.8% (95% CI: 89.4% – 96.4%). |
2. Sample Size Used for the Test Set and Data Provenance
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Clinical Performance (Validation Set):
- Sample Size: 498 samples.
- Data Provenance: The text does not explicitly state the country of origin. It indicates the samples were a "separate set of samples, none of which were used in establishing the reference range." The patient groups include Systemic Sclerosis (SSc) and various control groups (Systemic Lupus Erythematosus, Rheumatoid Arthritis, Idiopathic Inflammatory Myopathy, Mixed Connective Tissue Disease, Celiac disease, Autoimmune thyroiditis, Sjögren's syndrome, Infectious disease, Crohn's disease, Osteoarthritis, COPD, Chronic Kidney Disease, Vasculitis, Raynaud's, Diabetes, Asthma, Skin Disease). The infectious disease samples specify Hepatitis C virus, Epstein-Barr virus, Toxoplasmosis, Cytomegalovirus, Mycoplasma infection, and Borrelia virus. The study is presented as evidence for the device's performance, suggesting prospective collection or a well-characterized retrospective cohort.
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Comparison with Predicate Device:
- Sample Size: 539 samples (the 498 samples from the Validation Set plus 41 additional contrived samples).
- Data Provenance: Same as the clinical performance validation set, with additional contrived samples (diluted Scl-70 positive serum with negative serum).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not specify the number of experts or their qualifications for establishing the ground truth for the clinical diagnosis of systemic sclerosis (SSc) or other conditions used in the clinical validation set. It simply refers to "Diagnosis" in the tables relating to sensitivity and specificity. Given this is an in vitro diagnostic device, the ground truth for clinical conditions would typically be established by clinical diagnosis by treating physicians, potentially corroborated by other clinical and laboratory findings.
4. Adjudication Method for the Test Set
The document does not describe any specific adjudication method (e.g., 2+1, 3+1) for establishing the ground truth diagnoses in the test set.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No multi-reader multi-case (MRMC) comparative effectiveness study is mentioned. This device is an automated chemiluminescent immunoassay; therefore, human reader assistance and improvement with AI assistance are not applicable. The comparison is between the new automated device and a predicate ELISA (enzyme-linked immunosorbent assay), not human readers.
6. Standalone Performance Study
Yes, a standalone performance study was done. The entire document describes the standalone performance of the QUANTA Flash® Scl-70 assay system (algorithm/device only without human-in-the-loop performance, as it's an automated immunoassay) across various analytical and clinical characteristics. The clinical sensitivity and specificity are direct measures of this standalone performance.
7. Type of Ground Truth Used
- Clinical Performance (Sensitivity/Specificity): The ground truth was clinical diagnosis. For systemic sclerosis (SSc), this means patients diagnosed with SSc. For control groups, this refers to patients diagnosed with other autoimmune diseases or infectious diseases, or healthy individuals.
- Analytical Performance: Ground truth was established by controlled experimental conditions, such as known concentrations for precision, linearity, and interference studies, or controlled conditions for stability studies.
- Comparison with Predicate Device: The ground truth for this comparison was the result obtained from the legally marketed predicate device, QUANTA Lite® Scl-70 ELISA.
8. Sample Size for the Training Set
- Reference Range Establishment (for Cut-off): 254 subjects were used. The sample groups included individuals with Rheumatoid Arthritis, Systemic Lupus Erythematosus, Hashimoto's Thyroiditis, Hepatitis B Virus, Hepatitis C Virus, Inflammatory Bowel Disease, Drug Induced Lupus, Autoimmune atrophic gastritis, Biliary anastomatic stricture, and Healthy Individuals.
- Cut-off Adjustment: 19 systemic sclerosis samples that were positive on the predicate device were also used to aid in the final determination of the cutoff.
- The document does not explicitly describe a separate "training set" in the context of machine learning, as this is an immunoassay, but rather samples used for establishing the reference range/cut-off.
9. How the Ground Truth for the Training Set was Established
- Reference Range Establishment: The ground truth for the 254 subjects used to establish the reference range was based on their clinical diagnosis (e.g., Rheumatoid Arthritis, Systemic Lupus Erythematosus, or Healthy Individuals).
- Cut-off Adjustment: The additional 19 systemic sclerosis samples had a ground truth based on their positive results on the predicate device (QUANTA Lite® Scl-70 ELISA) and their clinical diagnosis of systemic sclerosis.
The cut-off was established in accordance with CLSI C28-A3c ("Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline - Third Edition") and adjusted based on the results from the SSc samples positive on the predicate device to optimize differentiation.
§ 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).