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Tina-quant Cystatin Gen.2 is an in vitro test for the quantitative determination of cystatin C in human serum and plasma on Roche/Hitachi cobas c systems. Cystatin C measurements are used as an aid in the diagnosis and treatment of renal diseases.

The Roche Tina-quant Cystatin C Gen.2 assay provides quantitative measurement of the cystatin C that is present in human serum and plasma. The reagents are packaged in a cassette with two bottles labeled with their instrument positioning, R1 (Reagent 1) and R2 (Reagent 2).

R1 contains a solution of polymers in MOPS-buffered saline with preservative and stabilizers. R2 is latex particles coated with anti-cystatin C antibodies (rabbit) in glycine buffer with preservatives and stabilizers.

Human cystatin C agglutinates with the antibody coated latex particles. The aggregate is determined turbidimetrically.

The provided text describes a 510(k) premarket notification for a modified in vitro diagnostic device, "Tina-quant Cystatin C Gen.2". The modifications primarily involve updated labeling information rather than changes to the device itself. Therefore, the study details are focused on validating these labeling changes.

Here's an analysis based on the provided document:

1. A table of acceptance criteria and the reported device performance

2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

• Sample Stability: Human serum and plasma patient samples were adjusted with cystatin C. The exact number of samples is not explicitly stated, but it mentions "patient samples" and that "These samples are split into two sets". The text does not specify the country of origin or whether the data was retrospective or prospective, but it implies prospective testing for stability.
• High dose hook-effect: A human serum pool was used, from which an 18-step dilution series was prepared. The exact volume or number of individual samples within the pool is not specified. Data provenance is not given.
• HARA interference: "Internal testing was done at Roche to confirm the customer results." The number of samples tested internally and the provenance of customer data are not detailed.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

Not applicable. This device is an in vitro diagnostic (assay for a biomarker), not an imaging or diagnostic device requiring expert interpretation of results for ground truth. Ground truth for an assay is typically established through reference methods or spiked samples with known concentrations.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set

Not applicable. Adjudication methods like 2+1 or 3+1 are typically used in clinical trials or studies where subjective interpretations (e.g., image readings) are being evaluated. For an IVD, the results are quantitative measures.

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

Not applicable. This study is for a laboratory assay, not an AI-assisted diagnostic tool for human readers.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

This refers to the performance of the analytical device itself. The studies described for sample stability, hook effect, and HARA interference were standalone evaluations of the assay's performance characteristics.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

• Sample Stability: The ground truth for sample stability was the result of the fresh sample at time zero, which is considered the baseline and implicitly the "true" concentration at that point.
• High dose hook-effect: The ground truth was the "known concentration" obtained from preparing a dilution series from a concentrated serum pool.
• HARA interference: The ground truth was based on confirming "falsely elevated results" observed in patient samples and corroborated by peer-reviewed literature.

8. The sample size for the training set

Not applicable. This device is an in vitro diagnostic reagent kit, not a machine learning or AI algorithm that requires a training set. The "training set" concept does not apply here.

9. How the ground truth for the training set was established

Not applicable, as there is no training set for this type of device.

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The Tina-quant Cystatin C Gen.2 is an in vitro test for the quantitative determination of cystatin C in human serum and plasma on Roche/Hitachi cobas c systems. Cystatin C measurements are used as an aid in the diagnosis and treatment of renal diseases.

Calibrator:
The C.f.a.s. (Calibrator for automated systems) Cystain C is for use in the calibration of quantitative Roche methods on Roche clinical chemistry analyzers as specified in the value sheets.

Control:
The Cystatin C Control Set Gen.2 is for use in quality control by monitoring accuracy and precision for the quantitative methods as specified in the value sheets.

Roche Tina-quant Cystatin C Gen. 2 reagent provides quantitative measurement of the cystatin C that is present in human serum and plasma. Assay: Reagents are packaged in a cassette with two bottles labeled with their instrument positioning, R1 (Reagent 1) and R2 (Reagent 2). R I contains solution of polymers in MOPS-buffered saline; preservative, stabilizers. R2 is latex particles in glycine buffer coated with anti-Cystatin C antibodies (rabbit); preservative, stabilizers.

Calibrator:
C.f.a.s. Cystatin C is a liquid, ready-to-use calibrator based on pooled delipidated human serum enriched with recombinant human Cystatin C produced in E. Coli. Single level calibrators with lot specific values are diluted on board the analyzer to create a 6-point calibration curve.

Control:
Cystatin C Control Set contains 3 controls based on pooled delipidated human serum enriched with human recombinant Cystatin C produced in E. Coli.

The provided text describes the analytical performance of the Tina-quant Cystatin C Gen. 2 test system. Here's a breakdown of the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

• Control 1 (1.00 mg/L): 1.7%
• Control 2 (1.84 mg/L): 0.9%
• Control 3 (4.12 mg/L): 0.7%
• Human Serum 1 (0.560 mg/L): 1.8%
• Human Serum 2 (2.80 mg/L): 0.6%
• Human Serum 3 (6.39 mg/L): 0.6% |
  | Precision (Intermediate Precision) | Not explicitly stated as a single "acceptance criteria" but implied by the provided data. | Total Imprecision (CV%)
• Control 1 (1.00 mg/L): 2.2%
• Control 2 (1.84 mg/L): 1.4%
• Control 3 (4.12 mg/L): 1.4%
• Human Serum 1 (0.560 mg/L): 2.0%
• Human Serum 2 (2.80 mg/L): 1.3%
• Human Serum 3 (6.39 mg/L): 1.1% |
  | Linearity (Serum) | Reported R² value close to 1 for linear regression. | R² = 0.999 (for Y = 1.001x - 0.0057) |
  | Linearity (Plasma) | Reported R² value close to 1 for linear regression. | R² = 0.999 (for Y = 1.000x + 0.0000) |
  | Lower Limit of Blank (LoB) | LoB claim = 0.30 mg/L | 0.30 mg/L (as the claim) |
  | Lower Limit of Detection (LoD) | LoD claim = 0.40 mg/L | 0.40 mg/L (as the claim) |
  | Lower Limit of Quantitation (LoQ) | LoQ claim = 0.40 mg/L at % CV of 13.3 | 0.40 mg/L at % CV of 13.3 (as the claim) |
  | Endogenous Interference (Hemoglobin, Lipemia, Bilirubin, Rheumatoid Factor) | Recovery within ± 0.100 mg/L of initial values for samples ≤ 1.00 mg/L and within ± 10% for samples > 1.00 mg/L. | All data passed the acceptance criteria; specific interferent limits provided (e.g., Lipemia up to 1000 L index, Hemolysis up to 1000 H index, Bilirubin up to 60 I index, Rheumatoid factor 0.1 mg/L, the deviation must be ≤ ± 10%. | All data passed the acceptance criteria; specific P/B equations provided (e.g., Serum vs. Li-heparin: y = 1.010x + 0.020, r = 1.000). |

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

• Precision and Reproducibility:
  • Test Set: Three human serum samples (0.56, 2.80, and 6.39 mg/L) and three control samples. Each sample was tested in two aliquots per run, two runs per day for 21 days.
  • Data Provenance: Not explicitly stated, but clinical studies are generally performed in a controlled laboratory environment. The context implies it's internal study data.
• Linearity/Assay Reportable Range:
  • Test Set: One batch of reagent, samples measured in triplicate. Two separate dilution series: plasma (thirteen levels) and serum (twenty-one levels).
  • Data Provenance: Not explicitly stated, but internal study data.
• Detection Limit (LoB, LoD, LoQ):
  • Test Set:
    • LoB: One blank sample tested n=5 with two analyzers and three reagent batches for six runs per day across three days.
    • LoD: Five low-analyte samples measured in singlicate on two analyzers with three reagent batches for six runs per day across three days.
    • LoQ: A low-level sample set (prepared by diluting 5 human serum samples) tested in 2 replicates per sample on 5 days, one run per day on one cobas c 501 analyzer.
  • Data Provenance: Not explicitly stated, but internal study data.
• Analytical Specificity (Endogenous Interference):
  • Test Set: One pool of human serum spiked with interferent vs. a second pool without, mixed in different ratios to create a dilution series. Tested at two levels of Cystatin C.
  • Data Provenance: Not explicitly stated, but internal study data.
• Analytical Specificity (Common Drug Interference):
  • Test Set: Two sample pools (low and high Cystatin C) divided into aliquots. One aliquot served as reference; others spiked with drugs. Samples determined in triplicate.
  • Data Provenance: Not explicitly stated, but internal study data.
• Method Comparison with Predicate Device:
  • Test Set: 103 human serum samples.
  • Data Provenance: Not explicitly stated as retrospective or prospective, but likely prospective for the comparison study. The country of origin is not specified.
• Matrix Comparison:
  • Test Set: 57 tubes collected per anticoagulant (Li-heparin, K2-EDTA, K3-EDTA, Gel Separation Tube).
  • Data Provenance: Internal study data.
• Expected Values/Reference Range:
  • Test Set: n=273 subjects from a US panel of healthy subjects.
  • Data Provenance: Prospective study from the US.

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

Not applicable. This device is an in-vitro diagnostic test for quantitative determination of Cystatin C. The performance evaluation relies on laboratory measurements and statistical analysis against established analytical performance metrics, not expert interpretation of images or clinical cases for ground truth.

4. Adjudication Method for the Test Set

Not applicable, as the evaluation is based on quantitative measurements and statistical methods, not human interpretation that would require adjudication.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC comparative effectiveness study was not done. The context describes an in-vitro diagnostic device, not an imaging or diagnostic aid that would typically involve human readers.

6. If a Standalone (i.e. algorithm only without human-in-the loop performance) was done

Yes, the studies described are standalone performance evaluations of the Tina-quant Cystatin C Gen. 2 test system. The device itself produces quantitative measurements without human-in-the-loop performance influencing the measurement output. The studies evaluate the analytical performance of the system directly.

7. The Type of Ground Truth Used

The "ground truth" for the performance studies is the reference method or expected/true concentration of Cystatin C.

• For precision, it's the statistical variability around the measured mean.
• For linearity, it's the expected linear relationship between serially diluted samples and their measured concentrations.
• For detection limits, it's the inherent chemical/physical limits of the assay.
• For interference studies, it's the known concentration of the analyte without the interferent, and the known concentration of the interferent itself.
• For method comparison, the predicate device's results serve as a comparative "truth" to establish substantial equivalence.
• For matrix comparison, serum results are compared as a baseline for other plasma types.
• For expected values, the ground truth is the statistically derived reference interval from a healthy population.
• For traceability, the device is standardized against the ERM-DA471/IFCC reference material, which acts as the ultimate "ground truth" for Cystatin C measurement.

8. The Sample Size for the Training Set

This information is not provided in the document. The studies described are performance validation studies, not directly describing a machine learning algorithm's "training set." If the device uses an internal algorithm (not specified if it's a machine learning algorithm), the training set for that algorithm is not detailed.

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

This information is not provided in the document. As mentioned above, the document details analytical performance studies rather than the development of a machine learning model's training which would require ground truth establishment for a training set.

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