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Determination of serum and plasma bilirubin is useful in the screening of liver function disorders or in the diagnosis of jaundice.

When a sample is mixed with the reagent containing the detergent and the vanadate, at around pH3, direct bilirubin in the sample is oxidized to biliverdin. This causes the absorbance of yellow, specific to bilirubin, to decrease. Therefore, the direct bilirubin concentration in the sample can be obtained by measuring the adsorbances before and after the vanadate oxidation.

This document is a 510(k) Summary of Safety and Effectiveness for the Wako Direct Bilirubin V assay. It highlights that the device is based on a chemical oxidation method and can determine direct bilirubin concentration in serum and plasma samples. The primary goal of the submission is to add plasma as an approved sample type to an already existing and approved device (Wako's previous Direct Bilirubin assay, 510(k) #970986).

1. Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state specific performance acceptance criteria in numerical terms (e.g., sensitivity, specificity, accuracy thresholds). Instead, the crucial acceptance criterion for this 510(k) submission is "substantial equivalency" to the previously marketed device (Wako's Direct Bilirubin assay, 510(k) #970986).

The reported device performance is:

• "shows good correlation with conventional methods"
• "practically no interference by coexistent serum and plasma substances"
• "convenient ready-to-use liquid type reagent"

Table of Acceptance Criteria and Reported Device Performance:

2. Sample Size Used for the Test Set and Data Provenance

The document does not provide details on the sample size used for the test set or the data provenance (e.g., country of origin, retrospective/prospective). It only states that the submission adds the use of plasma as a sample to the previously cleared device. Therefore, any testing related to substantial equivalence for plasma samples would have been conducted, but the specific details are not included in this summary.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

This submission describes an in vitro diagnostic (IVD) assay for measuring bilirubin, not an imaging device or one requiring expert interpretation of results for ground truth establishment. Therefore, the concept of "experts used to establish ground truth" as it applies to, for example, radiologists interpreting images, is not applicable here. The "ground truth" for chemical assays typically relies on established reference methods, calibrated standards, and a comparison to a predicate device.

4. Adjudication Method for the Test Set

Given that this is an IVD assay and not an imaging or interpretative device, an "adjudication method" in the sense of multiple experts resolving discrepancies is not applicable. Assay results are quantitative measurements, and accuracy is typically assessed against reference methods or the performance of a predicate device.

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

A Multi-Reader Multi-Case (MRMC) comparative effectiveness study is not applicable for this type of in vitro diagnostic assay. MRMC studies are typically used to evaluate the diagnostic performance of human readers, often with and without AI assistance, in interpreting medical images or other complex data. This device is an automated chemical assay.

6. Standalone Performance Study

The information provided within this summary does not explicitly describe a separate "standalone" study in the way it might be for an AI algorithm. However, the 510(k) submission itself implicitly represents a standalone performance evaluation by comparing its performance to predicate devices (the previous Wako Direct Bilirubin assay) and conventional methods. The core of a 510(k) relies on demonstrating that the new device is "substantially equivalent" in performance to a legally marketed predicate device. This inherently means its performance was evaluated independently to make that claim.

7. Type of Ground Truth Used

The ground truth for chemical assays like this is typically established through:

• Comparison to established, validated reference methods: The summary mentions "good correlation with conventional methods," indicating such comparisons were likely part of the underlying studies.
• Calibrated standards: Assays are typically validated against precisely known concentrations of the analyte (bilirubin in this case).
• Performance of the predicate device: The primary ground truth for this specific submission is the performance of the legally marketed predicate device (Wako's previous Direct Bilirubin assay, 510(k) #970986), against which "substantial equivalency" is claimed.

8. Sample Size for the Training Set

The concept of a "training set" with a specified sample size is primarily relevant to machine learning or AI algorithms. This device is a chemical reagent-based assay. Therefore, a "training set" in the machine learning sense is not applicable. The development of such assays involves extensive R&D, formulation optimization, and analytical validation.

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

As noted above, a "training set" in the context of AI is not applicable for this chemical assay. The validation of the assay's chemical principles and performance would have involved laboratory studies using known bilirubin concentrations, spiked samples, and clinical samples analyzed by reference methods and the predicate device to ensure accuracy, precision, and linearity.

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