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An enzyme-linked immunosorbent assay (ELISA) designed for the detection and measurement of circulating antibodies to native DNA. These autoantibodies are often associated with systemic lupus erythematosus (SLE) and give positive results in screening tests for antinuclear antibodies.

An enzyme-linked immunosorbent assay (ELISA) designed for the detection and measurement of antibodies to native DNA in human serum.

The ELISA methodology is commonly used for serum antibody evaluations. Purified native DNA has been attached to the inner surfaces of the microwell plate. During the initial incubation step, antibodies in patient serum bind specifically to the immobilized antigen and remain in place after a wash step.

A second antibody which is conjugated to horseradish peroxidase (HRP) is used to recognize the "heavy + light" chain regions of the patient's DNA antibodies that remain after the wash step. In the wells where the second antibody remains bound. the conjugated HRP catalyzes a color change in the substrate. After the reaction is stopped, the color is read in an EIA Plate reader.

Acceptance Criteria and Study Details for Hemagen® DNA Kit (K962276)

Based on the provided text, the Hemagen® DNA Kit is an enzyme-linked immunosorbent assay (ELISA) designed for the detection and measurement of antibodies to native DNA in human serum, primarily associated with systemic lupus erythematosus (SLE).

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria for this device are not explicitly stated in numerical thresholds but are implied through "comparative studies" demonstrating "substantial equivalence" to the predicate device. The performance data provided focuses on precision and comparative analytical performance.

2. Sample Size and Data Provenance for Test Set

• Sample Size:
  • Disease state patients: 100 serum specimens.
  • Apparently healthy blood donors: 40 serum specimens.
  • Total Test Set: 140 serum specimens.
• Data Provenance: The text states "serum specimens from different patients with known or suspected autoimmune disease" and "apparently healthy blood donors." The country of origin is not specified, but the use of "patient" and "blood donors" suggests these were clinical samples. The study appears to be retrospective as the samples are described as "from different patients with known or suspected autoimmune disease" indicating prior diagnosis or clinical status.

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

• The text does not explicitly state the number of experts used to establish the ground truth for the test set or their specific qualifications.
• However, the predicate device (Hemagen VIRGO® Anti-nDNA IgG IFA Kit) was used as the basis for comparison, implying that the ground truth for the test set was established by the results from this predicate device and clinical information ("known or suspected autoimmune disease").

4. Adjudication Method for the Test Set

• An adjudication method was used for discrepant samples between the proposed device and the predicate.
• Method: "The nine discrepant samples were evaluated by hemagglutination for resolution." This suggests a third, independent method was used to arbitrate differences, effectively acting as a form of "2+1" adjudication for the discrepant samples.

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

• No, a MRMC comparative effectiveness study was not done.
• This device is an automated in vitro diagnostic (ELISA) kit, not a device requiring human interpretation of images or complex data where reader variability would be a primary concern for comparative effectiveness. The comparison is between two assay methods and their accuracy against clinical status/predicate.

6. Standalone Performance Study

• Yes, a standalone study was performed in terms of analytical performance. The "Proposed Device" (Hemagen dsDNA Kit) was evaluated for its precision (inter-assay and intra-assay reproducibility), correlation with the WHO standard, and its performance against interfering substances and prozone effect. These are intrinsic performance characteristics of the algorithm/device itself.
• The comparative testing against the predicate device also serves as a standalone performance evaluation for the proposed device's diagnostic accuracy (sensitivity and specificity) relative to an established method.

7. Type of Ground Truth Used (Test Set)

• The ground truth for the test set was primarily based on the results of the predicate device (Hemagen VIRGO® Anti-nDNA IgG IFA Kit) combined with the clinical status of the patients ("known or suspected autoimmune disease") or healthy status ("apparently healthy blood donors").
• For discrepant samples, hemagglutination was used as an additional, independent method to resolve the ground truth.

8. Sample Size for the Training Set

• The document does not explicitly provide information on a separate "training set" for the device. As an ELISA kit, its performance is based on the inherent biochemical properties and cutoff values established during its development. These types of devices typically undergo extensive analytical validation to establish parameters like cutoff points, but this process might not be explicitly described as "training" in the same way an AI model would have a training set.
• The data presented (precision, WHO correlation, interfering substances, prozone) are generally part of analytical validation studies, not necessarily "training" data as understood for machine learning.

9. How Ground Truth for the Training Set Was Established

• Given that no explicit "training set" is mentioned in the context of an algorithm or machine learning, the concept of "ground truth for the training set" as it applies to AI/ML is not directly applicable here.
• For an ELISA kit, the establishment of cutoff values and optimal assay parameters would have occurred during the development phase. This process would involve testing numerous known positive and negative samples, likely characterized by clinical diagnosis, other established laboratory tests, and potentially reference materials (like the WHO standard), to determine the concentration or optical density thresholds that best differentiate between positive and negative results. However, the document does not detail this specific process or the sample sizes involved in establishing these parameters.

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