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The FREND™ PSA Plus as performed on the FREND™ system, is a quantitative in vitro diagnostic test which measures total Prostate Specific Antigen (PSA) in human serum and plasma. The NanoEnTek FREND™ PSA Plus is designed for in vitro DIAGNOSTIC USE ONL Y for the quantitative measurement of total Prostate Specific Antigen (PSA) in human serum, heparinized plasma, and EDTA plasma using the FREND™ System. This device is indicated for the serial measurement of total PSA in serum, heparinized plasma and EDTA plasma to be used as an aid in the management of patients with prostate cancer.

The FREND™ PSA Plus is indicated for use in clinical laboratories upon prescription by the attending physician as an aid to clinicians in managing patients with prostate cancer.

The information provided from this test may supplement decision-making and should only be used in conjunction with routine monitoring by a physician and the use of other diagnostic procedures. Because of the variability in the effects of various medications used in the treatment of prostate cancer, clinicians should use professional judgment in the interpretation of PSA results as an indicator of disease status.

The FREND™ PSA Plus is a rapid fluorescence immunoassay that measures prostate specific antigen (PSA) in human serum and in lithium heparin and EDTA plasma using the FREND™ system. The FREND™ PSA Plus is intended for use as an aid for prostate cancer management. The FREND™ PSA Plus Test is a single use fluorescence immunoassay designed to quantify the concentration of total PSA in serum and lithium heparin and EDTA plasma samples. The specimen is added by the operator to the sample inlet with a transfer pipet, allowing the appropriate volume of sample (30 µL) to be delivered into the FREND™ PSA Plus Test Cartridge. The Cartridge is then placed into the FREND™ System, which is programmed to begin analysis once the sample has reacted with the reagents. The reaction and analysis time is approximately 6 minutes. The PSA quantification is based on the amount of fluorescence detected by the FREND™ System at the FREND™ PSA Plus Test Cartridge window. A higher level of fluorescence is indicative of a higher PSA concentration. In other words, the magnitude of the fluorescent signal is directly proportional to the amount of total PSA in the sample.

The FREND™ System is a bench top fluorescence reader containing a touchscreen user interface. The System has a slot that accepts the FREND™ PSA Plus Test Cartridge (which contains the reagents and sample), and is programmed to analyze the Test when the sample has fully reacted with the on-board in cartridge reagents. Results of the test are displayed on the screen and can be printed on an optional printer through the RS232C interface.

Here's a summary of the acceptance criteria and study findings for the FREND™ PSA Plus on the FREND™ system, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

| Performance Metric | Acceptance Criteria (Stated or Implied) | Total (Total CV%) | |
| Site-to-Site Value) | 3.50% | 1.57% | 1.67% | 3.47% | 1.61% | 2.06% | |
| Inter-cartridge | 18.45% | 6.81% | 7.94% | 20.03% | 6.17% | 7.49% | |
| Total (Total CV%) | 20.87% | 7.74% | 10.79% | 21.22% | 7.69% | 9.81% | |

Note: The document explicitly states "acceptance criteria" for some tests (e.g., dilution linearity, spiked recovery, interference) but for others (e.g., imprecision, method comparison), it describes the results and concludes they are "acceptable" or "compared well," implying that the performance met internal thresholds comparable to predicate devices.

2. Sample Sizes and Data Provenance

• Clinical Samples: 1219 evaluable clinical serum samples.
  • Provenance: Prospectively collected stored samples were utilized for the clinical study. No specific country of origin is explicitly stated, but NanoEnTek is a Korean company with a CRO (DOCRO, Inc.) in the US, and testing was done at both NanoEnTek facilities and CLIA licensed facilities in the US.
• Precision (Analytical):
  • Intra-assay/inter-assay/complex imprecision: Three clinical samples (0.186, 2.757, 16.625 ng/mL) assayed in duplicates twice a day for 20 days using a single lot cartridge (total 80 measurements per sample).
  • Multi-Site, Multi-Lot Imprecision: Four replicates each of Material A, B, C and two replicates of QC 1, 2, 3 were evaluated in two runs performed for five days at each of three geographically diverse sites. This yielded a total of 40 results on each material per site, and 120 total replicates for each material across all sites.
• Dilution Linearity & Recovery: A serum pool with elevated PSA (34 ng/mL) was diluted to seven levels, plus neat and zero samples. Each level was tested in 6 replicates.
• Spiked Recovery: A serum pool from females (tPSA < 0.01 ng/mL) was spiked with 3 known PSA levels. Samples were assayed before and after spiking (number of replicates not explicitly stated, but table shows 3 replicates per spike level).
• Analytical Sensitivity (LOD/LOQ): 5 blank samples and 5 low PSA concentration samples were tested in 12 replicates each.
• High Dose Hook Effect: A concentrated sample of purified PSA antigen tested neat and on dilution (number of replicates not specified).
• Interfering Substances and Assay Specificity: Not explicitly stated, but samples were tested according to CLSI protocol EP7-A.
• Method Comparison:
  • Prostate cancer samples: Single point samples (n = 85) and earliest sample from serially monitored subjects (n = 75), for a total of 160 samples (tPSA < 25 ng/mL).
  • Serially Monitored Subjects: 75 subjects undergoing serial monitoring for prostate cancer. A total of 236 point-to-point determinations for each assay.
• Sample Matrix Comparison Study: 36 matched sets (serum, lithium heparin, EDTA plasma, sodium citrate) were collected, aliquoted, frozen, and run.
• Reagent Stability Studies: Three different lots of cartridges were tested over 15 months at three-month intervals using five standard specimens.

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

The document does not explicitly state the number of experts or their specific qualifications (e.g., radiologist with X years of experience) for establishing the ground truth for the test set in the clinical performance section.

• For the serial monitoring study, "Disease status for the patients was determined by the physician. This Disease Status was used to determine Progression or No Progression from a clinical perspective." This implies a medical professional established the clinical ground truth. The nature of this determination included "other laboratory tests, patient interviews, physical examinations, and imaging studies of a variety of types."

4. Adjudication Method for the Test Set

The document does not describe a formal adjudication method (like 2+1 or 3+1 consensus) for the clinical test set. The clinical status for serially monitored patients was determined by "the physician" and was used as the ground truth.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not conducted. This device is an in vitro diagnostic assay, not an imaging device or AI-assisted diagnostic tool that would typically involve human readers interpreting cases with and without AI assistance. The clinical study compares the device's performance to a predicate device and clinical status, but not the improvement of human reader performance.

6. Standalone (Algorithm Only) Performance

Yes, numerous standalone performance studies were done. The FREND™ PSA Plus is an automated immunoassay system, and its analytical and clinical performance is its standalone performance. The entire "Performance Data Summary - Analytical Testing" and "Performance Data Summary - Clinical Testing" sections detail the standalone performance of the assay and system without human intervention in the measurement process (though human input is required to operate the system and interpret results in a clinical context).

7. Type of Ground Truth Used

• Analytical Studies:
  • Precision, Dilution Linearity, Spiked Recovery, Sensitivity, Hook Effect, Interference: Ground truth was based on known concentrations of PSA, characterized reference materials, or clinically established levels of interfering substances. For example, for dilution linearity, the "Expected Value" was the ground truth based on known dilutions. For spiked recovery, the "Concentration Added" was the ground truth.
• Clinical Studies:
  • Disease Cohorts (Normal, Benign, Malignant): Ground truth was based on patient diagnoses (e.g., "Benign prostate disease," "Prostate Cancer") established through clinical assessment (including other diagnostic tests and potentially pathology results, though not explicitly detailed for this specific aspect).
  • Serial Monitoring: Ground truth for "Progression" or "No Progression" was based on "the clinical status of the patients as measured by other laboratory tests, patient interviews, physical examinations, and imaging studies of a variety of types." This is essentially patient outcomes data/clinical diagnosis as determined by a physician.

8. Sample Size for the Training Set

The document does not explicitly describe a separate "training set" for an algorithm in the way that would typically be detailed for an AI/ML device. This device is an immunoassay, and its performance characteristics (like linearity, precision, etc.) are established through traditional analytical and clinical validation studies, rather than machine learning model training on a distinct dataset. The "development" and "optimization" of the assay would typically involve internal samples and experiments, but these are not referred to as a "training set" in the context of this 510(k) submission.

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

Since a "training set" for an AI/ML algorithm is not described, the method for establishing its ground truth is not applicable/provided. The analytical and clinical performance data presented here are for the validation and verification of the device's performance against established metrology principles and clinical outcomes.

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