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The Diamedix Is-Rubella IgG Test Kit is an Enzyme Immunoassay (EIA) for the qualitative and quantitative determination of IgG antibodies in human serum to aid in the assessment of the patient's immunological response to infection with rubellaand in the determination of the immune status of individuals, including females of child-bearing age. The evaluation of acute and convalescent sera can aid in the diagnosis of recent or current infection with rubella. These reagents can be used either manually or in conjunction with the MAGO® Plus Automated EIA Processor.

The Is-Rubella IgG Test System is an enzyme-linked immunosorbent assay (ELISA) for the qualitative and quantitative detection of IgG to rubella in human serum. Partially purified rubella antigen is attached to a solid phase microtiter well. Diluted test sera are added to each well. If antibodies which recognize the rubella antigen are present in the patient sample they will bind to the antigen on the well. After incubation, the wells are washed to remove unbound antibody. An enzyme labeled anti-human immunoglobulin (conjugate) is added to each test well. If antibody is present the enzyme-linked antibody will bind to it. After incubation, the wells are washed to remove unbound conjugate. A substrate solution is then added to each well. If enzyme is present from the prior step, the reaction is stopped and the color intensity is measured photometrically producing an indirect measure of the specific antibody present in the patient sample.

Here's a breakdown of the acceptance criteria and the study details for the Diamedix Is-Rubella IgG Test System, based on the provided text:

Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined "acceptance criteria" in terms of specific quantitative thresholds that the device must meet to be considered effective. Instead, it presents performance characteristics in comparison to existing marketed tests (predicate devices) and a CDC reference panel. The overall goal appears to be demonstrating substantial equivalence to these predicate devices.

However, we can infer performance targets from the reported results, particularly overall agreement, sensitivity, and specificity. The data is presented as a comparison, implying that similar performance to established methods is the 'acceptance criteria.'

Study that Proves the Device Meets the Acceptance Criteria:

The document describes several studies conducted to demonstrate the performance characteristics of the Is-Rubella IgG Test System.

1. Comparison Testing (Main Performance Study):

   • Sample Size (Test Set):
     • Site #1: 198 prospective (fresh) sera.
     • Site #2: 178 prospective (fresh) sera.
     • Site #3 (Diamedix Corp.): 270 retrospective (frozen) sera (263 by MAGO Plus).
     • All sites: 100 retrospective selected negative and low positive sera (panel provided by Diamedix).
     • Total unique samples could be estimated as 198 + 178 + (270 - possible overlap with the 100 panel, not explicitly stated if it's separate) + 100. At least 646 samples if the 100 panel is unique from the 270 from Site #3.
   • Data Provenance:
     • Site #1: S. Florida area (prospective).
     • Site #2: West region (prospective).
     • Site #3 (Diamedix Corp.): S. Florida blood donors (retrospective/frozen).
     • The 100 retrospective negative/low positive sera were "provided by Diamedix," suggesting a potentially internal or curated source.
   • Number of Experts & Qualifications (Ground Truth): Not applicable for this comparison study, as the ground truth was established by "currently used testing methods" (predicate EIAs) and a "referee EIA method" for discordant samples. No human expert interpretation was used as ground truth.
   • Adjudication Method: For discordant samples, a "referee EIA method" was used for further resolution. The specific details of how discrepancies between the new device and predicate were handled by the referee method (e.g., if the referee method became the final truth) are implied rather than explicitly stated as a formal adjudication process.
   • Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study: No, this was not an MRMC study. It was a comparison of a new assay against predicate assays.
   • Standalone Performance: Yes, the performance characteristics (sensitivity, specificity, agreement) of the Is-Rubella IgG Test System are reported as a standalone algorithm/device performance against the predicate devices.
   • Type of Ground Truth: The "ground truth" for the comparison studies was derived from existing, marketed EIA methods (predicate devices) and a "referee EIA method" for resolving discordant results. It is relative to these comparator assays, not pathology, outcomes data, or expert consensus in the diagnostic sense.
   • Sample Size (Training Set): Not explicitly stated. This document focuses on verification/validation, not development.
   • Ground Truth for Training Set: Not explicitly stated. Assumed to be internal development or established reference methods during product development.

2. CDC Serum Panel Data:

   • Sample Size (Test Set): A panel of 100 characterized serum samples (82% positive, 18% negative).
   • Data Provenance: Centers for Disease Control and Prevention (CDC) serum panel. This is an external, characterized reference source.
   • Number of Experts & Qualifications (Ground Truth): Not applicable. The CDC panel itself is a predefined, characterized ground truth.
   • Adjudication Method: Not applicable; the panel has predefined characteristics.
   • Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study: No.
   • Standalone Performance: Yes, the device's accuracy in identifying positive and negative samples from this panel is reported in standalone fashion.
   • Type of Ground Truth: Masked, characterized serum panel from the CDC. This is a highly reliable, external reference standard.
   • Sample Size (Training Set): Not applicable. This panel is used for independent verification.
   • Ground Truth for Training Set: Not applicable.

3. Correlation, Linearity, and Precision Studies: These studies evaluate technical performance aspects of the assay.

   • Sample Size (Test Set):
     • Correlation (Manual vs. MAGO Plus): 193 samples.
     • Linearity: "Several strongly positive serum samples" (specific number not given), diluted and assayed in duplicate. Figures show data for "one patient sample."
     • Correlation to WHO Standard: "Several dilutions of the WHO Standard" assayed in triplicate.
     • Quantitative Data (Serum pairs): "Multiple two-fold dilutions of several strongly positive sera."
     • Cross-Reactivity Data: 49 sera negative for rubella IgG antibodies but positive for one or more other viruses.
     • Precision: Seven serum samples spanning the reportable range, plus reference standards and controls. Tested in triplicate in 2-3 separate runs on 3 different days across 3 sites.
   • Data Provenance: Not specified for individual samples, but the precision studies involved three sites: Site #1, Site #2, and Site #3 (Diamedix Corp.).
   • Number of Experts & Qualifications (Ground Truth): Not applicable for these technical performance studies.
   • Adjudication Method: Not applicable.
   • Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study: No.
   • Standalone Performance: Yes, these are all standalone evaluations of the device's technical performance characteristics.
   • Type of Ground Truth: For linearity, it's based on expected dilution patterns. For WHO correlation, it's against the WHO 1st International Standard for Anti-Rubella Immunoglobulin. For cross-reactivity, it's against known positive samples for other viruses (verified by other marketed tests). For precision, it's about the reproducibility of the device's own measurements.
   • Sample Size (Training Set): Not explicitly stated.
   • Ground Truth for Training Set: Not explicitly stated. Assumed to be internal methods during product development.

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