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EliA SmDP is intended for the in vitro semi-quantitative measurement of IgG antibodies directed to Sm in human serum and EDTA-plasma to aid in the clinical diagnosis of systemic lupus erythematosus (SLE) in conjunction with other laboratory and clinical findings. EliA SmDP uses the EliA IgG method on the instrument Phadia 2500/5000.

The method-specific reagents are identical with K132631 (EliA SmDº on Phadia 250), but are filled in containers specific for the Phadia 2500/5000 instrument. Each device consists of:

• Test Wells: -EliA SmDP Wells are coated with a synthetic SmD3 peptide – 4 carriers (12 wells each), ready to use;
• EliA Sample Diluent: PBS containing BSA, detergent and 0.095% (w/v) sodium azide - 6 bottles, 48 mL each, ready to use; or 6 bottles, 400 mL each, ready to use;
• -EliA IgG Conjugate 50 or 200: ß-Galactosidase labeled anti-IgG (mouse monoclonal antibodies) in PBS containing BSA and 0.06% (w/v) sodium azide – 6 wedge shaped bottles, 5 mL each, ready to use; or 6 wedge shaped bottles, 19 mL each, ready to use
• EliA IgG Calibrator Strips: Human IgG (0, 4, 10, 20, 100, 600 µg/L) in PBS containing BSA, detergent and 0.095% (w/v) sodium azide - 5 strips, 6 singleuse vials per strip, 0.3 mL each, ready to use;
• -EliA IgG Curve Control Strips: Human IgG (20 µg/L) in PBS containing BSA, detergent and 0.095% (w/v) sodium azide - 5 strips, 6 single-use vials per strip, 0.3 mL each, ready to use;
• EliA IgG Calibrator Well: Coated with mouse monoclonal antibodies 4 carriers (12 wells each), ready to use.

The Phadia EliA Immunodiagnostic System is an automated system for immunodiagnostic testing. The EliA reagents are available as modular packages, each purchased separately. All packages are required to carry out EliA SmDP tests.

Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The device under review is the EliA SmDP Immunoassay on the Phadia 2500/5000 instrument. The study primarily evaluated the performance of this new instrument platform compared to a previously cleared device (EliA SmDP on Phadia 250, K132631). The acceptance criteria for the new device's performance are largely demonstrated through its equivalence to the predicate device.

2. Sample Size and Data Provenance for the Test Set

• Precision/Reproducibility:
  • Sample Size: Multiple samples tested in 84 replicates per sample (7 days x 3 instruments x 4 replicates/run). The specific number of distinct samples for the precision study is not explicitly stated beyond "The study was performed with 1 run/day over a period of 7 days."
  • Data Provenance: Not explicitly stated, but typically these types of analytical validation studies are conducted in-house by the manufacturer. No indication of specific country or retrospective/prospective outside of the internal lab setting.
• Linearity/Reportable Range:
  • Sample Size: Four patient serum samples.
  • Data Provenance: Not explicitly stated, likely internal lab testing using patient samples.
• Detection Limit (LoD) and Quantification Limit (LoQ):
  • Sample Size: One blank sample and five low-level samples measured in 12 replicates in each of 6 runs (total 72 blank determinations, 360 low-level determinations).
  • Data Provenance: Internal lab testing.
• Method Comparison (Instrument Comparison):
  • Sample Size: More than 100 samples (specifically, "≥10% of the samples within ±25% of the medical decision point").
  • Data Provenance: Not explicitly stated, but these are patient samples run on both the predicate and new instruments. The text mentions "patient serum samples" for linearity, suggesting these would also be patient samples. Given the device is for SLE diagnosis, these would be relevant clinical samples. No information on country of origin or retrospective/prospective.

3. Number of Experts and their Qualifications for Ground Truth of Test Set

This type of immunoassay (EliA SmDP Immunoassay) directly measures the concentration of antibodies. The "ground truth" for the test set in this context refers to the actual concentration of the analyte or the true clinical status, which is not typically established by human experts interpreting images, but rather by reference methods or clinical diagnosis.

• For analytical performance (precision, linearity, detection limits), the "ground truth" samples are often characterized by their known concentrations or by being truly "blank" (zero concentration). This is determined by the assay itself or by careful preparation and measurement in a lab setting, not by human experts.
• For method comparison and demonstrating agreement around cut-offs, the "ground truth" for the samples is usually established by the predicate device's measurement or the clinical diagnosis of the patient. The clinical performance (sensitivity/specificity for SLE) was reviewed in the predicate device's submission (K132631) and relies on the clinical diagnosis of SLE. Therefore, for the present submission, human experts (clinicians) would have been involved in the original clinical diagnosis of SLE patients used to establish the cut-off values for the predicate device, but their specific number, qualifications, or adjudication methods are not part of this submission's detailed test set information because it refers back to the predicate.

4. Adjudication Method for the Test Set

Adjudication methods (e.g., 2+1, 3+1) are typically used when subjective interpretations by multiple human experts are compared to establish a "ground truth" for diagnostic imaging or similar scenarios.

• For this immunoassay, where the output is a semi-quantitative measurement (EliA U/mL), there is no mention or need for an adjudication method by human experts for the analytical performance studies. The measurements are objective.
• For the original clinical studies that established the assay's clinical utility and cut-offs (referenced from K132631), clinical diagnosis of SLE would have served as the "ground truth." The adjudication method for establishing those clinical diagnoses is not provided in this document, as it refers to a prior submission.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done.

• MRMC studies are typically used to assess how human readers perform with and without AI assistance, especially in radiology or pathology.
• This submission is for an in-vitro diagnostic (IVD) immunoassay, which does not involve human readers interpreting images or data in the same way that would necessitate an MRMC study. The comparison is between two automated instrument platforms.

6. If a Standalone (Algorithm Only) Performance Study was Done

Yes, the analytical and method comparison studies described are essentially standalone performance studies for the new Phadia 2500/5000 instrument platform operating the EliA SmDP Immunoassay.

• The device (the assay and instrument combination) operates autonomously to measure antibody concentrations. There is no "human-in-the-loop" component for the measurement process itself that would differentiate between standalone and assisted performance in this context. The instrument runs the assay and generates a numerical result, which is then interpreted by a clinician in conjunction with other findings.

7. Type of Ground Truth Used

• For analytical performance (precision, linearity, LoD/LoQ): Controlled reference materials, blank samples, and carefully characterized patient samples with known dilution factors were used.
• For method comparison: The measurements obtained from the predicate device (EliA SmDP on Phadia 250) served as the comparative "ground truth" as the intent was to show substantial equivalence between the two instrument platforms running the same assay reagents.
• For clinical cut-offs and performance: The document states that clinical performance values were reviewed in K132631, and the assay cut-offs were derived from clinical studies. This implies that the ultimate ground truth for establishing clinical utility and cut-offs was based on clinical diagnosis of systemic lupus erythematosus (SLE), likely established by expert clinicians using a combination of clinical findings, pathology, and other laboratory tests.

8. Sample Size for the Training Set

The provided document describes a 510(k) submission for adding a previously cleared assay to a new instrument platform. It does not explicitly mention a "training set" in the context of an AI/machine learning model.

• For an immunoassay like EliA SmDP, the "training" analogous to an AI model would be the initial development and optimization of the assay itself and the establishment of calibration curves. This process typically involves a large number of samples used during the R&D phase to define parameters and ensure robust performance, but these are not explicitly termed "training sets" in this document.
• The document primarily focuses on validation testing (analytical and method comparison) of the new instrument platform.

9. How the Ground Truth for the Training Set Was Established

As there is no distinct "training set" described for a machine learning algorithm in this document, the question of how its ground truth was established is not applicable in the AI/ML sense.

• However, if we consider the development of the original EliA SmDP assay (from the predicate K132631), the "ground truth" for calibrators and controls would be established metrologically, through dilutions of highly characterized human IgG standards. For the clinical cut-offs, as mentioned in point 7, this would have been established through extensive clinical studies where the ground truth was the definitive diagnosis of SLE based on established criteria and expert clinical judgment.

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