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The LIAISON® 25 TOTAL-D assay is a chemiluminescent immunoassay (CLIA) intended for the quantitative determination of 25-hydroxyvitamin D and other hydroxylated vitamin D metabolites in human serum, EDTA and Lithium heparin plasma. The LIAISON® 25 TOTAL-D assay is to be used as an aid in the assessment of vitamin D sufficiency in adults. The DiaSorin LIAISON® 25 TOTAL-D is intended to be used on the LIAISON® XL Analyzer.

The DiaSorin LIAISON® 25 TOTAL-D Control Set is intended for use as assayed quality control samples to monitor the accuracy and precision of the DiaSorin LIAISON® 25 TOTAL-D assay.

The DiaSorin LIAISON® 25 TOTAL-D Calibration Verifiers are assayed quality control materials intended for use in the quantitative verification of calibration and reportable range of the LIAISON® 25 TOTAL-D assay when performed on the LIAISON® XL Analyzer.

The LIAISON® 25 TOTAL-D consists of one Reagent Intergral with calibrators, which consists of: Magnetic Particles (2.4 mL) coated with goat antibody against 25 OH Vitamin D, protein, phosphate buffer, < 0.1% sodium azide. Assay Buffer (28.0 mL) with 7.5% ethanol, surfactants and 0.2% ProClin® as a preservative. Conjugate (4.5 mL) 25 OH Vitamin D conjugated to an isoluminol derivative. in phosphate buffer with10% ethanol, EDTA and 0.1% benzoic acid as a preservative. Calibrator 1 (1.2 mL) Human serum, BSA, <0.1% sodium azide and 25 OH Vitamin D. The calibrator concentrations (ng/mL) are referenced to standard preparations containing highly purified 25 OH Vitamin D. Calibrator 2 (1.2 mL) Human serum, BSA, <0.1% sodium azide and 25 OH Vitamin D. The calibrator concentrations (ng/mL) are referenced to standard preparations containing highly purified 25 OH Vitamin D.

The LIAISON® 25 TOTAL-D control consists of 2 levels of human serum, BSA, <0.1% sodium azide and 25 OH Vitamin D.

The LIAISON® 25 TOTAL-D calibration verifier consists of 4 levels of human serum, BSA. <0.1% sodium azide and 25 OH Vitamin D.

The DiaSorin LIAISON® 25 TOTAL-D assay is a chemiluminescent immunoassay (CLIA) for the quantitative determination of 25-hydroxyvitamin D and other hydroxylated vitamin D metabolites in human serum, EDTA, and Lithium heparin plasma. It is intended to be an aid in the assessment of vitamin D sufficiency in adults.

Here's an analysis of the acceptance criteria and the studies performed:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as pass/fail thresholds for each metric in the provided text. However, the study results are presented with implied acceptance based on the comparison to the predicate device and established clinical laboratory guidelines (e.g., CLSI documents).

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

• Method Comparison: 403 serum samples (391 included in analysis after excluding 12 below measuring range).
  • Data Provenance: De-identified residual serum samples obtained from a sample procurement organization (U.S. and/or European patients). Retrospective.
• Matrix Comparison: 64 matched patient sets (serum, lithium heparin plasma, and EDTA plasma samples).
  • Data Provenance: Not explicitly stated, but implied to be patient samples. Prospective.
• Reference Range Study: 395 samples.
  • Data Provenance: Adults (21-90 years) recruited from four sites in the contiguous US (northern, southern, central US). Prospective.
• Reproducibility/Precision: 6 coded frozen serum samples (panel) and 2 kit controls.
  • Data Provenance: Internal samples/controls.
• Dilution Linearity: Separate serum, SST (serum separator tubes), EDTA plasma, and lithium heparin plasma pools (original number of samples to create pools not specified).
  • Data Provenance: Internal pools created for the study.
• LoB/LoD/LoQ:
  • LoB: 6 blank sample aliquots.
  • LoD: 4 samples.
  • LoQ: 8 samples.
  • Data Provenance: Internal samples.
• Recovery: 5 high concentration serum samples and 5 low concentration serum samples.
  • Data Provenance: Internal samples.
• Interfering Substances: Vitamin D samples (30 ng/mL and 60 ng/mL) spiked with interfering substances.
  • Data Provenance: Internal samples.
• Cross-reactivity: Three serum pools (15, 50, 75 ng/mL 25 OH D) spiked with potential cross-reactants.
  • Data Provenance: Internal serum pools.

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

There is no mention of experts being used to establish ground truth in the traditional sense (e.g., radiologists interpreting images). For this type of in-vitro diagnostic device, the "ground truth" or reference values are established by other analytical methods or reference materials:

• Method Comparison: The predicate device, LIAISON® 25 OH Vitamin D TOTAL assay (K112725), served as the comparative "reference."
• Traceability and Value Assignment: Calibrators, controls, and calibration verifiers are traceable to UV spectrophotometric analysis of an in-house standard preparation using a commercially available 25-Hydroxyvitamin D. Master calibrators are prepared from a stock solution whose concentration is determined spectrophotometrically.
• Reference Range: The "ground truth" is the distribution of 25 OH Vitamin D levels in a statistically defined "apparently healthy" population, rather than expert consensus on individual cases.

4. Adjudication Method for the Test Set

Not applicable. This device is an in-vitro diagnostic (IVD) assay predicting a biochemical concentration, not a diagnostic imaging device requiring expert adjudication.

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

No. This is an in-vitro diagnostic device, not an imaging device that would typically involve human readers. Therefore, an MRMC study and analysis of AI vs. human reader improvement is not applicable.

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

Yes, the performance studies described (Method Comparison, Matrix Comparison, Linearity, LoB/LoD/LoQ, Recovery, Interfering Substances, Cross-reactivity, Reproducibility/Precision) evaluate the device's analytical performance in a standalone manner, without human interpretation of results beyond standard laboratory practices. The "algorithm" here is the chemiluminescent immunoassay technology performed on the LIAISON® XL Analyzer.

7. The Type of Ground Truth Used

The ground truth or reference values used for validation include:

• Comparison to a Predicate Device: For method comparison studies, the results from the previously cleared LIAISON® 25 OH Vitamin D TOTAL assay (K112725) served as the reference.
• Reference Standards/Spectrophotometric Analysis: For traceability, calibration, and control value assignment, established spectrophotometric methods using highly purified 25 OH Vitamin D standards were used.
• Defined Blanks and Spiked Samples: For LoB/LoD/LoQ, Recovery, Interfering Substances, and Cross-reactivity studies, samples with known (or zero) concentrations of the analyte or interfering substances were used.
• Population-Based Data: For reference range, the "ground truth" is derived from statistical analysis of a representative "apparently healthy" subject population.

8. The Sample Size for the Training Set

No explicit "training set" is mentioned in the context of machine learning. This device is a biochemical assay. The "training" for such devices typically involves:

• Method Development & Optimization: Internal studies and experiments conducted during the development phase to optimize reagent concentrations, incubation times, and other assay parameters.
• Calibration: The device uses a two-point calibrator to generate a stored master curve, which is essentially the "model" or "prediction function" for the assay. This calibration is derived from master calibrators whose values are assigned using reference materials.

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

Not applicable in the machine learning sense. For the calibration and internal optimization processes:

• The ground truth for calibrators is established through UV spectrophotometric analysis of an in-house standard preparation using commercially available 25-Hydroxyvitamin D.
• Master calibrators are then used to assign values to the kit calibrators, controls, and calibration verifiers by running them on multiple LIAISON XL analyzers with different reagent lots and taking mean results.

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