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EliA Scl-70s is intended for the in vitro semi-quantitative measurement of IgG antibodies directed to Scl-70 in human serum and plasma (heparin, EDTA) as an aid in the clinical diagnosis of scleroderma (diffuse form) in conjunction with other laboratory and clinical findings. EliA Scl-70s uses the EliA IgG method on the instrument Phadia 100.

EliA Scl-70s is intended for the in vitro semi-quantitative measurement of IgG antibodies directed to Scl-70 in human serum and plasma (heparin, EDTA) as an aid in the clinical diagnosis of scleroderma (diffuse form) in conjunction with other laboratory and clinical findings. EliA Scl-70s uses the EliA IgG method on the instrument Phadia 250.

The Phadia EliA immunodiagnostic system is automated system for immunodiagnostic testing. The EliA reagents are available as modular packages, each purchased separately. All packages except the positive and negative controls are required to carry out an EliA Scl-70° test.

The acceptance criteria and study detailed in the provided document pertain to the EliA™ Scl-70S Immunoassay, an in vitro semi-quantitative test for IgG antibodies directed to Scl-70.

Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria for the clinical performance (sensitivity and specificity). However, it reports the performance of the EliA Scl-70S based on its clinical study. For analytical performance, the acceptance criteria are implied by the reported results meeting generally accepted ranges for such assays.

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size for Analytical Performance Tests:
  • Precision/Reproducibility: 3 samples for Phadia 250, 1 batch for Phadia 100.
    • Phadia 100: 84 replicate determinations per sample (21 runs: 3 instruments x 7 runs each, over 7 days).
    • Phadia 250: 252 replicate determinations per sample (21 runs: 3 instruments x 7 runs each, over 7 days).
  • Linearity: 4 patient serum samples.
  • Hook Effect: One high positive serum sample.
  • Detection Limit (LoB/LoD): 6 blood donors. Each measured in 12 replicates in each of 6 runs on 6 different days (432 replicates per sample).
  • Endogenous Interference: 5 serum samples (2 negative, 2 around cut-off, 1 positive).
• Sample Size for Comparison Studies:
  • Method Comparison with Predicate Device: 390 serum samples.
    • Collected from patients with Scleroderma (SSc, n = 101), CREST (n = 33), MCTD (n = 37), SLE (n = 34), Sjögren's syndrome (SS, n = 26), Poly/Dermatomyositis (PM/DM, n = 5), Rheumatoid arthritis (RA, n = 30), various cancers (n = 20), various bacterial infections (n = 24), various viral infections (n = 26), and technical samples positive or equivocal for EliA Scl-70° (n = 54).
  • Matrix Comparison: 50 patients (serum, lithium heparin plasma, EDTA plasma collected from each).
  • Instrument Comparison: 24 positive, 8 equivocal, and 4 negative samples (total 36).
• Sample Size for Clinical Studies:
  • Clinical Sensitivity and Specificity: 336 clinically defined sera.
    • Diagnostic groups: Scleroderma (SSc, n=101) and Controls (n=235) which include other connective tissue diseases, bacterial/viral infections, cancer, and rheumatoid arthritis.
  • Assay Cut-off / Expected values: 400 apparently healthy blood donor samples from Caucasian individuals (equally distributed by sex and age).
• Data Provenance: The document does not explicitly state the country of origin for the patient or blood donor samples. It is implied to be retrospective as samples were "collected from patients with diagnosis of..." for the comparison and clinical studies. For the assay cut-off, "400 apparently healthy blood donor samples from Caucasian individuals" were used.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

The document does not specify the number of experts used or their qualifications to establish the ground truth for the clinical diagnosis of scleroderma (SSc) or other conditions in the test set. It states "clinically defined sera from patients with scleroderma or other connective tissue diseases, bacterial or viral infections, cancer or rheumatoid arthritis," implying that the diagnosis was based on standard clinical practice rather than a dedicated expert panel for this study.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method for establishing ground truth diagnoses for the clinical test set. Clinical findings are referenced as the basis for diagnosis ("clinically defined sera"), but no specific multi-reader adjudication process is mentioned for the study itself.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not performed or reported in this document. The device is a laboratory immunoassay, and its performance is evaluated against a predicate device and clinical diagnoses, not as an aid to human readers in interpreting images or other data.

6. Standalone (i.e., algorithm only without human-in-the-loop performance) Study

Yes, the study is inherently a standalone performance evaluation of the immunoassay itself. The reported performance characteristics (precision, linearity, detection limits, clinical sensitivity, specificity) reflect the algorithm's (immunoassay's) ability to detect the target antibodies in patient samples without direct human-in-the-loop interpretation once the sample is loaded into the automated Phadia instruments. The results are quantitative (EliA U/mL) leading to a categorical output (negative, equivocal, positive) based on predefined cut-offs.

7. The Type of Ground Truth Used

The ground truth used for the clinical study was clinical diagnosis. The document states "336 clinically defined sera from patients with scleroderma or other connective tissue diseases, bacterial or viral infections, cancer or rheumatoid arthritis." This implies that the ground truth was established by medical professionals through standard diagnostic procedures (e.g., patient history, physical examination, other laboratory tests, imaging, etc.) to arrive at a clinical diagnosis.

For the method comparison, the ground truth was essentially the results from the predicate device (INOVA QuantaLite™ Scl-70 ELISA), against which the new device's technical agreement was measured.

8. The Sample Size for the Training Set

The document does not explicitly describe a separate training set for the device's development or a study related to training a machine learning model. This immunoassay device is a chemical/biological test system with predefined reagents and a specific detection methodology, not a machine learning algorithm that typically requires a distinct training phase with a labelled dataset. Its calibration employs calibrators and controls.

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

As there is no explicit training set discussed in the context of machine learning or algorithm training, this question is not directly applicable. For the immunoassay, the "ground truth" for calibration and controls would be established by the manufacturer through rigorous characterization and standardization of the calibrator and control materials, often traceable to international reference preparations (e.g., WHO standards for IgG). The document mentions that "New batches of IgG calibrators are compared to a secondary standard (standardized with the IRP) or the IRP directly and adjusted accordingly to meet the correct concentration."

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