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The anti Cardiolipin Screen is indicated for the screening of patient serum for the presence of IgG, IgM, and IgA autoantibodies to cardiolipin . Autoantibodies to aCl are typically observed in patients with systemic lupus erythematosus and other connective tissue diseases. This assay is intended to be utilized as an aid in the diagnosis of antiphospholipid syndrome.

The ELISA methodology is commonly used for serum antibody evaluations. In this assay, purified bovine cardiolipin has been attached to the inner surfaces of microplate test wells by the manufacturer. The user adds diluted patient samples to the wells. Anticardiolipin antibodies in patient serum bind specifically to the cardiolipin antigen attached to the plate, and remain in place after a wash step.

A trivalent second antibody cocktail, consisting of peroxidase-conjugated goat anti-human IgG (Fc), IgM (u), and IgA (α), is added to the wells. After an incubation/wash step, TMB (tetramethylbenzidine) substrate is added. In the wells containing bound cardiolipin-anticardiolipin complexes, the peroxidase enzyme catalyzes a color change in the TMB substrate. After the reaction is stopped with dilute sulfuric acid, the color is read in an ELISA plate reader. Optical densities (ODs) of patient samples are compared to the OD of a reference serum included in the kit.

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

Device: Hemagen® aCL Screen anti Cardiolipin screening assay
Intended Use: Qualitative detection of IgG, IgM, and IgA autoantibodies to cardiolipin in human serum. Aid in the diagnosis of antiphospholipid syndrome.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria (e.g., "The device must achieve X% sensitivity and Y% specificity"). Instead, it presents the results of comparison testing to demonstrate substantial equivalence to predicate devices. The values presented below are the reported performance from this comparison.

2. Sample Size and Data Provenance for Test Set

• Sample Size for Test Set: 117 serum specimens
  • 38 (or 39 in combined table) samples from "patients positive for aCl" (Positive Panel)
  • 79 samples from "normal blood donors" (Normal Panels)
• Data Provenance: Not explicitly stated (e.g., country of origin). The document implies these were patient and normal donor samples, but does not specify if they were retrospective or prospective, or from what geographic region.

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

• Number of Experts: Not applicable/not mentioned.
• Qualifications of Experts: Not applicable/not mentioned.
  • The ground truth for the test set was established by comparison to predicate devices (Hemagen® Anti-Cardiolipin IgG and IgM, and Hemagen® Anti-Cardiolipin IgA Calibrator Reagents). This implies the predicate devices themselves served as the "expert" or reference standard for classification of whether a sample was positive or negative for aCl.

4. Adjudication Method for Test Set

• Adjudication Method: Not applicable. The samples were classified as "POS" or "NEG" based on the predicate devices. There was no mention of human expert adjudication or consensus methods used to resolve discrepancies between different interpretations or tests, beyond the direct comparison to the predicate devices.

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

• MRMC Study: No, an MRMC comparative effectiveness study was not done. This device is an immunoassay, not an imaging or diagnostic device requiring human reader interpretation in the same way. The study focuses on comparing the new device's analytical performance against existing predicate devices.

6. Standalone (Algorithm Only) Performance

• Standalone Performance: Yes, the described "Comparison Testing" section directly details the standalone performance of the Hemagen® aCL Screen. It compares the device's output (positive/negative) directly against the results obtained from the predicate devices which serve as the reference for classification. There is no human-in-the-loop performance described, as this is an automated immunoassay.

7. Type of Ground Truth Used

• Type of Ground Truth: The ground truth for the comparison testing was established by comparison with predicate devices. Specifically, samples were categorized as "positive for aCl" or from "normal blood donors," and the results from the proposed device were compared to the results from the legally marketed Hemagen® Anti-Cardiolipin IgG and IgM assays, and the Hemagen® Anti-Cardiolipin IgA Calibrator Reagents. This is an example of using a reference standard (predicate devices) to define the truth.

8. Sample Size for Training Set

• Sample Size for Training Set: Not explicitly stated as a distinct "training set." The 117 serum specimens mentioned in Section II ("Cutoff Serum Standardization") and Section III ("Comparison Testing") appear to be the primary dataset used for both optimizing the cutoff and evaluating the device's performance against predicates. It's possible the "Cutoff Serum Standardization" phase where ROC techniques were used could be considered a form of training or optimization, but a separate, distinct "training set" versus "test set" paradigm is not clearly delineated beyond this.

9. How Ground Truth for Training Set was Established

• How Ground Truth for Training Set was Established: For the "Cutoff Serum Standardization," where an optimized cutoff OD was derived:
  • 117 serum specimens from both "disease state and normal patient panels" were screened concurrently with both the proposed and predicate devices.
  • Receiver Operating Characteristic (ROC) techniques were employed to analyze the data from this concurrent testing.
  • The "optimized cutoff OD" was determined based on this ROC analysis and comparison testing relative to the predicate devices, aiming for a "relative analytical sensitivity of ≥ 97.0 %" (which became 100% in the final comparison). This indicates that the predicate devices' classifications likely served as the ground truth or gold standard against which the new device's performance was optimized.

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