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The CRP Vario assay [CRPVa] is for in vitro diagnostic use in the quantitative immunoturbidimetric determination of C-reactive protein in human serum and plasma (sodium and lithium heparin) using the ARCHITECT c Systems. Measurement of C-reactive protein is useful in the detection and evaluation of infection, tissue injury and inflammatory disorders.

CRP Calibrators (including CRP Calibrator Set, CRP Calibrator HS and CRP Calibrator WR) are intended to be used for the calibration of the CRP Vario for the quantitative determination of C-reactive protein in human serum or plasma samples.

The CRP Vario assay is intended for the quantitative immunoturbidimetric determination of C-reactive protein in human serum and plasma. It is supplied as a two-reagent kit. The kit contains Reagent 1 (Glycine buffer) and Reagent 2 (Anti-CRP polyclonal antibodies adsorbed on latex particles). Two different sizes of the product are available. The submission also describes CRP Calibrators (CRP Calibrator Set, CRP Calibrator HS, and CRP Calibrator WR) which are prepared by diluting CRP with human serum and stabilized by adding sodium azide.

Here's an analysis of the acceptance criteria and study as described in the provided document:

Acceptance Criteria and Device Performance for CRP Vario

1. Table of Acceptance Criteria and Reported Device Performance

Note: The document explicitly refers to an "Acceptance Criteria" column for Method Comparison in Table 15-3. For other performance characteristics, the "acceptance criteria" can be inferred by comparing the candidate device's stated performance to that of the predicate device, or by general statements about meeting recommendations or consistency with original submissions.

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

• Method Comparison Test Set:

  • High Sensitivity Method: N = 111 human serum samples
  • Standard Method: N = 119 human serum samples
  • Wide Range Method: N = 119 human serum samples
  • Data Provenance: The document states "Human serum samples, spanning the measuring range, were tested." No information is provided regarding the country of origin or whether the data was retrospective or prospective.

• Limit of Quantitation (LoQ) Test Set:

  • The study used serum pools diluted with SeraSub (a synthetic serum) to create 8 low-level analyte samples (0.08, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, and 0.005 mg/dL).
  • Each sample was tested in a minimum of 10 replicates per run, with 2 runs per day over 3 days, resulting in a total of 60 replicates per sample.

• Linearity Test Set:

  • A high CRP serum pool was mixed with a low serum pool to generate 12 concentrations.
  • Each concentration level was tested in triplicate determinations.

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

This section is not applicable to this type of device and study. The CRP Vario is an in vitro diagnostic device that quantifies C-reactive protein. Its performance is evaluated against reference methods (e.g., predicate devices, established analytical protocols) and CLSI guidelines, not against expert human interpretations of images or clinical reports. There are no "experts" establishing a subjective ground truth in the way described for AI in image analysis.

4. Adjudication Method for the Test Set

This section is not applicable. As an in vitro diagnostic device, the performance is determined by quantitative measurements and statistical comparisons with reference methods, not by adjudication of interpretations by multiple human readers.

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

No, an MRMC comparative effectiveness study was not done. This type of study evaluates human reader performance often in the context of imaging diagnostics. The CRP Vario is an in vitro diagnostic for laboratory analysis, not a device requiring human interpretation in this manner.

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

Yes, the studies reported here (Method Comparison, Linearity, Limit of Quantitation) are standalone performance evaluations of the CRP Vario assay. The device itself is an automated immunoturbidimetric system (ARCHITECT c8000 system) for quantitative measurement, operating without human interpretation of the final result, beyond standard laboratory quality control and result reporting.

7. The Type of Ground Truth Used

The "ground truth" for the performance evaluation of the CRP Vario was established by:

• Reference Methods / Predicate Device: For the Method Comparison study, the candidate CRP Vario (traceable to ERM-DA472/IFCC) was compared against a Beckman Coulter CRP Latex REF. OSR6199 (traceable to CRM 470) on an AU5800 platform.
• CLSI Guidelines: Formal CLSI (Clinical and Laboratory Standards Institute) protocols (EP09-A3 for Method Comparison, EP06-A for Linearity, EP17-A2 for LoQ) were followed, indicating that the acceptable statistical and analytical measures defined by these standards served as the basis for evaluating performance.
• Dilution Series / Known Concentrations: For Linearity and LoQ, the "ground truth" was derived from precisely prepared serum pools and their serial dilutions to known or targeted concentrations.

8. The Sample Size for the Training Set

This section is not applicable. The CRP Vario is a re-submission for a modification of an existing in vitro diagnostic device, not an AI/ML device that requires a distinct "training set" in the computational sense. Its performance is characterized through analytical verification and validation studies.

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

This section is not applicable for the reasons stated in point 8.

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