Please find below the analytical performance studies performed to validate the accuracy, precision and reliability of the U-Scan, with respect to the detection of the 4 measurements : pH, Specific Gravity, Ketones, Vitamin C.

The studies are performed according to the acceptance criteria used for semi-quantitative colorimetric studies. We estimate that we fulfill the precision and accuracy requirements if at least 90% of the predicted values fall within the expected range (correct block) and 100 % of the predicted values are within +/- 1 block of the correct block.

All tests are done using real urine samples, with pools and positive controls supplied from ThermoFisher or Merck, as well as real, fresh and independent human samples for the trueness study.

1. Precision Studies (repeatability and repoducibility)

1.1 Repeatability:

7 levels (concentrations) are evaluated for pH, 5 for ketones, 3 for vitamin C and 3 for specific gravity. For each concentration or level, at least 27 strips are tested with a minimum of 3 runs, with 3 different readers per run and at least 3 different cartridges per reader. 1 product lot (batch) is evaluated for repeatability.  

1.2 Reproducibility:

7 levels (concentrations) are evaluated for pH, 5 for ketones, 3 for vitamin C and 3 for specific gravity. For each concentration or level, at least 27 strips are tested with a minimum of 3 runs, with a minimum of 3 different readers per run and on at least 3 different cartridges. A minimum of 3 strips is done per reader and the 3 runs are done on each of the 3 product lots (batches) of cartridges.
 

2. Analytical Specificity

Ketones and Vitamin C quantification by the colorimetric reaction used on our strips is prone to false positive results. These molecules can be found in urine because of a pharmaceutical treatment or because of a physical condition. Some molecules used for cleaning up the toilet bowl are also tested as they can also interfere with the chemical reaction. 

2.1 pH:

• N/A

No cleaning solvents should penetrate the U-Scan reader as they may interfere with the accuracy of the pH values returned. 

2.2 Ketones

The following molecules have been tested for the Ketones reaction. For each molecule, 5 solutions are prepared with the potential interferent (0 mM, 1.5 mM, 4 mM, 8 mM, 16 mM Ketones). For each of the 5 solutions, 7 strips are tested. For the mock samples, 5 solutions (0 mM, 1.5 mM, 4 mM, 8 mM, 16 mM Ketones) are prepared in the absence of the interferent.  The comparison of the strips with and without the interferent allows us to check if the molecule interferes with the reaction.

Exogenous substances that interfere with the results to give a false positive.

• Captopril (>0.01 mg/mL)
• Nitrofurantoin (>0.1 mg/mL)

Endogenous substances that interfere with the results to give a false positive.

• Creatinin (8 mg/mL)

Cleaning solvents that can interfere with the colorations to give false results.

• Acetic acid (1 mmol) 
• Citric acid (1.6 mmol)
• Sodium Hypochlorite (1%)

2.3 Vitamin C

The following molecules have been tested for the Vitamin C reaction. For each molecule, 3 solutions are prepared with the potential interferent (0 mM, 0.6 mM, 2.8 mM Vitamin C). For each of the 3 solutions, 7 strips are tested. For the mock samples, 3 solutions (0 mM, 0.6 mM, 2.8 mM Vitamin C) are prepared in the absence of the interferent.  The comparison of the strips with and without the interferent allows to check if the molecule interferes with the reaction,

Exogenous substances that interfere with the results to give a false positive :

• Phenazole pyridine (2.5 µmol/mL) 
• Captopril (>10 µg/mL)
• Riboflavin (Vitamin B2) (12 µg/mL)

Endogenous substances that interfere with the results to give coloration that is not due the presence of ketones :

• None

Cleaning solvents that can interfere with the colorations to give false results :

• Acetic acid (>1 mmol) 
• Citric acid (>1.6 mmol)
• Sodium Hypochlorite (>0.01%)

2.4 Specific Gravity

• Urines with pH values above 7.5 could lead to an underestimation of the specific gravity values.

3. Method Comparison

• N/A

4. Trueness

This study intends to evaluate the difference between the values predicted by the U-Scan and the values measured by a gold standard. A benchtop pHmeter is used to measure the True Values of the pH solutions and a digital refractometer is used to measure the true values of the Specific Gravity solutions. 113 different real human urine samples are used and are analyzed using the U-Scan, the pHmeter and the refractometer. Values must lie in the green and yellow zone in order to be considered accurate, with a minimum of 90% of the values lying in the green zone and a maximum of 10% of the values in the yellow zone.

5. Stability

Cartridges are stored in their aluminum pouch at room temperature during the time T (from 0 to 6 months) and then incubated at 90% relative humidity for 3 months at room temperature. Pads are then tested in triplicate at the indicated concentrations for each biomarker. Values are then compared to known standard values for each concentration of the biomarker. If the value is in the standard range, the pad is noted in range and if the value is outside of the range the measure is noted out of range.