(45 days)
UriDynamics StoneGuard™ II Test Strips are intended for semiquantitative measurement of pH and specific gravity in fresh urine. They can be used to monitor conditions that may cause the formation of kidney stones, namely trends in urinary pH and hydration status.
Confirm Low™ and Confirm High™ Control Solutions are intended for in vitro (external) use only, for use as control materials for StoneGuard™ II Test Strips only.
UriDynamics StoneGuard™ II Test Strips consist of plastic carriers with two reagent pads attached. The pads respond to pH and specific gravity. StoneGuard™ II Test Strips are stored in an opaque vial with desiccant and are ready to use. Results may be read between 30 and 60 seconds after wetting with a freshly-voided urine sample. Results are obtained by comparing the color developed on the pads with a printed color chart. The results are semi-quantitative. Control solutions, Confirm Low™ and Confirm High™, intended for use with StoneGuard™ II Test Strips, are also included in this submission. Confirm Low™ and Confirm High™ contain buffers and salts that give a known response with StoneGuard™ II Test Strips. Confirm Low™ and Confirm High™ Control Solutions are ready to use in dispensers, and contain no biological ingredients.
Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied by the "Accuracy" and "Correlation of Consumer & Reference Results" sections. The reported performance refers to the results obtained in the studies.
| Acceptance Criteria (Implied) | Reported Device Performance (StoneGuard™ II) |
|---|---|
| pH Accuracy | 100% of results within one-half color block of the expected value. |
| pH Correlation (Consumer) | 92.5% of participant results within ± one-half pH unit of the reference value. |
| Specific Gravity Accuracy | At least 75% of results within one-half color block of the expected value. |
| Specific Gravity Correlation (Consumer) | 92.5% of participant results within ±0.010 of the reference. |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Test Set: 107 participants for the clinical studies.
- Data Provenance: The study was conducted at four sites in Indiana, USA. The data is prospective, as it involved recruiting participants for a "Clinical Studies" section, indicating data collected specifically for the purpose of this evaluation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts
The document does not explicitly state the number of experts or their qualifications for establishing ground truth. Instead, it refers to "reference results obtained by refractometer for specific gravity and pH meter for pH" (for specificity, Corning Model 313 pH Meter and eclipse Handheld Refractometer). This suggests that established laboratory instruments served as the "ground truth" rather than human experts.
4. Adjudication Method for the Test Set
The document does not describe any human adjudication method (e.g., 2+1, 3+1). The ground truth was established by laboratory instruments.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
There was no MRMC comparative effectiveness study involving AI mentioned in the document. This device is a visual reagent test strip, not an AI-powered diagnostic. The study focused on assessing untrained consumers' ability to interpret results visually compared to reference instruments.
6. If a Standalone (i.e. algorithm only without human-in-the loop performance) was done
This is not applicable, as StoneGuard™ II is a visual test strip requiring human interpretation, not an algorithm. The "standalone" performance here refers to the performance of the chemical pads themselves responding to pH and specific gravity, which was tested for accuracy and precision against reference instruments.
7. The Type of Ground Truth Used
The ground truth used was instrument-based reference values.
- For pH: Readings from a Corning Model 313 pH Meter.
- For specific gravity: Readings from an eclipse Handheld Refractometer.
8. The Sample Size for the Training Set
The document does not mention a "training set" in the context of machine learning or algorithm development, as this is a chemical reagent strip. The studies described are for validation of the final product.
9. How the Ground Truth for the Training Set Was Established
Not applicable, as there is no training set in the context of this device. The "ground truth" for the performance evaluation was established by laboratory instruments as described in point 7.
§ 862.1550 Urinary pH (nonquantitative) test system.
(a)
Identification. A urinary pH (nonquantitative) test system is a device intended to estimate the pH of urine. Estimations of pH are used to evaluate the acidity or alkalinity of urine as it relates to numerous renal and metabolic disorders and in the monitoring of patients with certain diets.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 862.9.