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For semi-quantitative determination of pH, leukocytes, nitrite, protein, glucose, ketone bodies, urobilinogen, bilirubin and blood in urine by reflectance photometry with the Urisys 2400 photometer.

The Urisys 2400 Urine Test Strips are used in conjunction with the Urisys 2400 photometer. The Urisys 2400 photometer is an automated urinalysis system, class I exempt device, regulation number 21CFR 862.2900. The Urisys 2400 photometer determines specific gravity, sample color, and sample clarity and reflectance measurements of test parameters on the Urisys 2400 Urine Test Strips.

The Urisys 2400 Urine Test Strips are intended for the semi-quantitative determination of various analytes in urine. The study presented compares its performance to the predicate device, the Roche Diagnostics Chemstrip 10 S-UA test strips (K934042).

Here's a breakdown of the acceptance criteria and study details:

1. Table of Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state numerical acceptance criteria for each analyte that must be met for the Urisys 2400 Urine Test Strip to demonstrate substantial equivalence. Instead, the performance evaluation relies on a comparison of results between the Urisys 2400 system and the predicate device (Chemstrip 10 S-UA) when measuring patient samples, and a comparison against a reference method (microscopic evaluation for leukocytes, color comparison for others) for some analytes. The goal is to show comparable performance.

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

• Sample Size: The document mentions "patient samples". For pH, "205 of 200 samples" is referenced, which is likely a typo and probably means "200 samples" or "205 samples". For blood, both "patient samples" and "spiked samples" were used. More specific numbers for other analytes are not explicitly stated, but the overall context of comparing against a predicate implies a substantial number of test samples. For instance, the pH test result mentions "205 of 200 samples", which is unusual, but likely refers to a total of 205 samples with either 200 agreement or 200 used in a specific calculation.
• Data Provenance: Not explicitly stated, but clinical studies for medical devices are typically conducted in the country where the manufacturer seeks market approval or relevant clinical sites globally. Given the submitter is Roche Diagnostics Corporation in Indianapolis, IN, the data is likely from the United States. The study is prospective in nature, as it involves testing the new device and comparing its performance to a predicate and reference methods.

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

• Number of Experts: Not explicitly stated.
• Qualifications of Experts: For leukocytes, "microscopic evaluation" is used as a reference method, which is typically performed by trained clinical laboratory professionals or pathologists. For other analytes like pH, visual comparison for color scale changes might involve qualified laboratory personnel, but this is not detailed.

4. Adjudication Method for the Test Set

• Adjudication Method: Not explicitly stated. For the comparison against the predicate device, it's a direct comparison of results. For analytes where a reference method (like microscopy for leukocytes) is used, the reference method itself serves as the ground truth, and the device's reading is directly compared to it. Any discrepancies would typically be reviewed by an expert.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

• No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This study focuses on the performance characteristics of the device (test strips read by an automated photometer) versus a predicate device and reference methods, not on human reader performance with or without AI assistance.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

• Yes, a standalone performance study was done. The Urisys 2400 photometer automatically reads the test strips and determines the results. This is an algorithm-only evaluation, as the device provides semi-quantitative results without human intervention in the result interpretation process itself, only in sample application and loading.

7. The Type of Ground Truth Used

• Predicate Device Comparison: The performance of the predicate device (Chemstrip 10 S-UA) itself served as a primary "ground truth" or standard of comparison to demonstrate substantial equivalence for most analytes.
• Reference Methods:
  • Microscopic Evaluation: Used for leukocytes. This is a common and established laboratory reference method.
  • Spiked Samples: Used for blood to evaluate the limit of detection, where the known concentration of the analyte (hemoglobin) in the spiked sample serves as the ground truth.
  • Color Comparison/Established Methods: For other analytes like pH, where visual or other established laboratory methods are typically used as references. The document doesn't detail these, but implies standard methods were used.

8. The Sample Size for the Training Set

• The document does not explicitly state the sample size for a training set. This is a 510(k) submission, and the focus is on performance validation for substantial equivalence rather than explicit algorithm training data. The "training" for such electrochemical/optical systems is typically factory calibration and robust quality control, not data-driven machine learning algorithms in the sense of a training set for AI. The device uses reflectance photometry, meaning its internal "rules" are based on physical-chemical principles and pre-programmed algorithms to interpret color changes, not a distinct "training set" in the context of deep learning.

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

• As mentioned above, there isn't a "training set" in the typical machine learning sense for this device. The "ground truth" for calibrating and setting up such an automated system involves using chemically defined standards, known positive and negative controls, and potentially a range of clinical samples with established values determined by reference laboratory methods, used during the device's development and manufacturing calibration to ensure accurate reflectance readings and interpretation. This process is part of quality control and manufacturing, rather than a distinct "training set" study for regulatory submission.

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