(396 days)
for the semi-quantitative measurement of IgG antibodies to cytomeqalovirus in serum and plasma (EDTA, heparin or sodium citrate) as an indication of past or current infection with cytomegalovirus. This product is not FDA cleared for use in testing blood or plasma donors.
The AxSYM CMV IgG assav is a Microparticle Enzyme Immunoassay (MEIA) for the semi-quantitative measurement of IgG antibodies to cytomeqalovirus in serum and plasma (EDTA, heparin or sodium citrate) as an indication of past or current infection with cytomegalovirus.
Here's a breakdown of the acceptance criteria and the study proving device performance, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance (AxSYM CMV IgG) |
|---|---|
| Relative Agreement | 99.8% (1194/1197) |
| Relative Sensitivity | 99.5% (589/592) |
| Relative Specificity | 100% (605/605) |
Note: The document states that the predicate device (Vidas CMV IgG) has a "Relative Specificity" of 98.1% and a "Relative Sensitivity" of 100%. While the AxSYM device's performance is compared against the predicate as part of establishing substantial equivalence, the text doesn't explicitly state what the acceptance criteria for these metrics were for the AxSYM device itself, beyond demonstrating close proximity or superiority to the predicate. However, given the reported performance numbers, it implies the acceptance criteria were met by showing comparable or better performance.
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: 1200 patient specimens.
- Data Provenance: The specimens were evaluated at "2 U.S. laboratories and 1 European laboratory," indicating a multi-center study across different geographic regions. The text refers to "patient specimens," suggesting they are from real patients, but it does not specify whether they were collected retrospectively or prospectively.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not mention the use of experts to establish ground truth. Instead, it compares the AxSYM device's performance against a "legally marketed EIA (ELFA)" which serves as the comparator or "reference" method. For resolving discordant results, "2 additional legally marketed assays" were used, effectively acting as a 'tie-breaker' or confirmation.
4. Adjudication Method for the Test Set
For discordance, a method akin to a "2+1" or "3+1" adjudication was used.
- Initial Comparison: AxSYM vs. legally marketed EIA (ELFA).
- Discordance Resolution: If there was a difference between AxSYM and the initial EIA (ELFA), the specimen was re-evaluated using "2 additional legally marketed assays." The outcome of these two additional assays determined the 'resolved' truth.
- Specific Example: "Of the 3 specimens positive by EIA (ELFA) and negative by AxSYM, all 3 were negative after resolution," implying that both additional assays agreed with the AxSYM result (negative) over the initial EIA (ELFA) result (positive).
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No, an MRMC comparative effectiveness study was not done. This study is for an in vitro diagnostic (IVD) device (a laboratory test) that measures antibodies, not an imaging device requiring human interpretation of images. Therefore, the concept of "human readers" or "AI assistance" in that context does not apply.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done
Yes, the study describes the standalone performance of the AxSYM CMV IgG assay. This is an automated immunoassay where the device itself performs the measurement and provides a semi-quantitative result without real-time human interpretation affecting the immediate outcome. The results presented (Relative Agreement, Sensitivity, Specificity) are direct outputs of the device's performance compared to a reference method.
7. The Type of Ground Truth Used
The ground truth was established by:
- Initially, a "legally marketed EIA (ELFA)" served as the primary comparator.
- For discordant results, "2 additional legally marketed assays" were used for resolution. This indicates a consensus or reconciliation of established, legally marketed diagnostic assays rather than pathology, expert consensus, or outcomes data in the traditional sense for image interpretation.
8. The Sample Size for the Training Set
The document does not provide information about a specific "training set" or its size for the AxSYM CMV IgG assay. This type of in vitro diagnostic device typically undergoes substantial development and analytical validation, but the summary mainly focuses on the clinical performance study (the "test set" described above) used for regulatory submission.
9. How the Ground Truth for the Training Set Was Established
As no training set information is provided, there is no description of how its ground truth was established.
§ 866.3175 Cytomegalovirus serological reagents.
(a)
Identification. Cytomegalovirus serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies to cytomegalovirus in serum. The identification aids in the diagnosis of diseases caused by cytomegaloviruses (principally cytomegalic inclusion disease) and provides epidemiological information on these diseases. Cytomegalic inclusion disease is a generalized infection of infants and is caused by intrauterine or early postnatal infection with the virus. The disease may cause severe congenital abnormalities, such as microcephaly (abnormal smallness of the head), motor disability, and mental retardation. Cytomegalovirus infection has also been associated with acquired hemolytic anemia, acute and chronic hepatitis, and an infectious mononucleosis-like syndrome.(b)
Classification. Class II (performance standards).