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VIDAS® NEPHROCHECK® is an automated test for use on the VIDAS® 3 instrument for the immunoenzymatic quantitative determination of TIMP-2 (Tissue Inhibitor of Metalloproteinase-2) and IGFBP-7 (Insulin-like Growth Factor-Binding Protein 7) proteins in human urine using the ELFA technique (Enzyme Linked Fluorescent Assay) for calculation of the AKIRISKTM Score.

The VIDAS® NEPHROCHECK® assay is intended to be used in conjunction with clinical evaluation in patients who currently have or have had within the past 24 hours acute cardiovascular and or respiratory compromise and are ICU patients as an aid in the risk assessment for moderate or severe acute kidney injury (AKI) within 12 hours of patient assessment. The VIDAS® NEPHROCHECK® test is intended to be used in patients 21 years of age or older.

Each VIDAS® NEPHROCHECK® kit contains: x60 NEPH Reagent Strips, x60 NEPH Solid Phase Receptacles (SPR), 1 NEPH control and 1 NEPH calibrator. The VIDAS® NEPHROCHECK® principle combines an enzyme immunoassay competition method with a final fluorescent detection (ELFA).

The Solid Phase Receptacle (SPR®) serves as the solid phase as well as the pipetting device for the assay. The interior of the NEPH SPR is coated with mouse monoclonal lgG anti-IGFBP-7 andanti-TIMP-2.

The Reagent Strips consist of 10 wells covered with a labeled foil seal. Well 1 is designated for the sample. Six of the wells contain conjugate, wash buffers and substrate. Last well contains the fluorescence substrate.

All of the assay steps are performed automatically by the instrument.

Two detection steps, one for each protein, are performed successively in Well 10.

· The first step is a classical detection step with measurement of the substrate background and incubation of the substrate in the bottom of the SPR®, to generate the first fluorescent signal, which is specific for the IGFBP-7 protein.

· Before the second detection step, the antibodies and proteins in the bottom of the SPR® are removed using the cleaning solution contained in Well 5. The previously used substrate in Well 10 is removed and replaced by fresh substrate contained in Well 9. A new substrate background is then measured, and the substrate is incubated in the top of the SPR® to generate the second fluorescent signal, which is specific for the TIMP-2 protein.

For each protein, the intensity of the fluorescence is proportional to its concentration in the sample. At the end of the test, the protein concentrations are calculated by the instrument in relation to the two calibration curves, one corresponding to each protein, and encoded in the MLE data.

The instrument calculates the AKIRISK™ Score, which is defined as the product of the concentrations of the two proteins, expressed in ng/mL, divided by 1000:

AKIRISK™ Score = ([TIMP-2] x [IGFBP-7]) / 1000

The result of the VIDAS® NEPHROCHECK® assay is reported as the AKIRISK™ Score.

Here's a breakdown of the acceptance criteria and study information for the VIDAS® NEPHROCHECK® device, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state "acceptance criteria" in a separate section with pass/fail thresholds for a primary clinical endpoint. Instead, it presents various analytical and clinical performance characteristics. The clinical performance is compared implicitly to the predicate device to establish substantial equivalence.

Here's an interpretation of relevant performance characteristics reported:

2. Sample Sizes and Data Provenance (for test sets):

• Diagnostic Accuracy Studies (Topaz & Opal cohorts):
  • The document does not explicitly state the sample sizes for the Topaz and Opal cohorts used in the diagnostic accuracy studies.
  • The document implies these were clinical studies involving ICU patients, but the geographical origin (e.g., country of origin) and whether they were retrospective or prospective are not specified.

3. Number of Experts and their Qualifications (for ground truth in test sets):

• The document does not provide information on the number or qualifications of experts used to establish ground truth for the clinical test sets (Topaz and Opal cohorts). It only states that the device is "intended to be used in conjunction with clinical evaluation," suggesting clinical data forms the basis of the ground truth for AKI status.

4. Adjudication Method (for the test set):

• The document does not specify any adjudication method used for establishing the ground truth of AKI status in the clinical test sets.

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

• No, an MRMC comparative effectiveness study was not done. The device is a diagnostic test (an in vitro diagnostic device) that provides a quantitative score (AKIRISK™ Score), not an imaging-based AI system that human readers interpret. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply here. The device itself generates the score for the clinician to use in conjunction with other clinical evaluations.

6. Standalone (Algorithm Only) Performance:

• A standalone performance study was done. The VIDAS® NEPHROCHECK® assay itself is the "algorithm only" in this context. The reported clinical performance (sensitivity and specificity) are standalone performance characteristics of the diagnostic test at a specific cut-off. The device provides a quantitative score, and its performance as a standalone test for risk assessment is what is reported.

7. Type of Ground Truth Used:

• The ground truth for the clinical performance (diagnostic accuracy) is implied to be based on the clinical evaluation of patients for moderate or severe Acute Kidney Injury (AKI) within 12 hours of patient assessment. This would likely involve standard clinical definitions of AKI, such as those based on changes in serum creatinine and/or urine output, as defined by established guidelines (e.g., KDIGO criteria). The document does not explicitly state the specific AKI definition used for ground truth.

8. Sample Size for the Training Set:

• The document does not provide information on the sample size for any training set. As this is an immunoenzymatic assay rather than a machine learning algorithm that is "trained" in the typical sense, there isn't a "training set" like there would be for an AI model. The development of such assays involves extensive analytical validation and optimization, but not necessarily a "training set" with ground truth in the AI context.

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

• As there's no mention of a traditional "training set" for an AI algorithm (see point 8), this information is not applicable/provided. The assay's parameters would have been optimized through laboratory studies and analytical development, validated against known standards and samples, rather than "trained" on a labeled dataset in the way an AI model is.

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