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ST AIA-PACK 25-OH Vitamin D is designed for in vitro diagnostic use only for the quantitative measurement of total 25-hydroxyvitamin D (25-OH vitamin D) in human serum, Na heparinized or EDTA plasma on TOSOH AIA System Analyzers. The Tosoh ST AIA-PACK 25-OH Vitamin D is intended as an aid in the determination of Vitamin D sufficiency.

The ST AIA-PACK 25-OH Vitamin D Calibrator Set is intended for In Vitro Diagnostic Use Only for the calibration of the ST AIA-PACK 25-OH Vitamin D assay.

The AIA-PACK 25-OH Vitamin D Control Set is.intended for IN VITRO DIAGNOSTIC USE ONLY for performing quality control procedures with the ST AIA-PACK 25-OH Vitamin D assay.

Device Description

The ST AIA-PACK 25-OH Vitamin D is a one-step delayed competitive enzyme immunoassay which, after sample pretreatment, is performed entirely in the ST AIA-PACK 25-OH Vitamin D test cup. Sample pretreatment reagents (containing sodium hydroxide) disassociate 25-OH vitamin D from its binding proteins in the test sample. 25-0H vitamin D present in the pretreated sample is bound to 25-OH vitamin D-specific monoclonal antibody immobilized on magnetic beads. After that, the enzyme-labeled 25-OH vitamin D is added to the reaction mixture. The enzyme-labeled 25-0H vitamin D competes with 25-0H vitamin D for binding to the antibody on magnetic beads in the reaction mixture.

After the second incubation, the magnetic beads are washed to remove the unbound enzymelabeled 25-OH vitamin D and are then incubated with a fluorogenic substrate, 4methylumbelliferyl phosphate (4MUP). The amount of enzyme-labeled 25-OH vitamin D that binds to the beads is inversely proportional to the 25-OH vitamin D concentration in the test sample. A standard curve is constructed, and unknown 25-OH vitamin D concentrations are calculated using this curve.

AI/ML Overview

Here's a breakdown of the acceptance criteria and the study details for the ST AIA-PACK 25-OH Vitamin D device, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" for precision, linearity, or correlation. Instead, it presents the results of these performance characteristics studies. The implied acceptance is that the reported performance is acceptable for the intended use and demonstrates substantial equivalence to the predicate device. For the purpose of this table, I will use the "Differences" table from the substantial equivalence section as a proxy for some acceptance criteria where direct comparisons were made to the predicate. For other performance characteristics, the reported results are presented.

Performance Characteristic	Acceptance Criteria (Implied/Predicate Comparison)	Reported Device Performance
Assay Technology	Fluorescence Immunoassay (or comparable)	Fluorescence Immunoassay
Incubation Time	Shorter than predicate (110 min)	10 minute cycle
Reference Range	Comparable to predicate (9.0 - 37.6 ng/mL)	10.8 to 54.75 ng/mL
Limit of Detection	Comparable to predicate (1.5 ng/mL)	2.6 ng/mL
Detection Range	Comparable to predicate (4.8 - 100.0 ng/mL)	4.0 ng/mL - 120.0 ng/mL
Calibrator Format	Lyophilized (or comparable to predicate)	Lyophilized
Calibrator Range	0-100 ng/mL (or comparable to predicate)	0-165 ng/mL
Controls Format	Lyophilized (or comparable to predicate)	Lyophilized
Controls Levels	Similar to predicate (e.g., 2 levels)	Two levels at approximately 20 and 80 ng/mL
Intra-assay Precision (CV%)	Not explicitly stated, typically <10-15%	Ranged from 1.2% to 7.3%
Total Precision (CV%)	Not explicitly stated, typically <15-20%	Ranged from 2.0% to 7.4%
Linearity Range	N/A (demonstrated)	4 ng/mL to 150 ng/mL
Method Comparison (Correlation	Slope ~1, Intercept ~0, R > 0.95 (typical)	Slope: 0.934, Intercept: 2.53, R: 0.944 (Deming)
Matrix Comparison (Serum vs Na Heparin)	Slope ~1, Intercept ~0, R > 0.95 (typical)	Slope: 0.993, Intercept: -0.390, R: 0.995 (Deming)
Matrix Comparison (Serum vs EDTA Plasma)	Slope ~1, Intercept ~0, R > 0.95 (typical)	Slope: 1.041, Intercept: 0.091, R: 0.994 (Deming)
Cross-reactivity	Minimal for non-target analytes (<10-20%)	25-OH D2: 101.1%, 25-OH D3: 99.2%, 3-epi 25-OH D2: 131.3%, 3-epi 25-OH D3: 107.7%, 24,25-(OH)2 D2: 5.2%, others <0.1-18.1%
Interference	Recovery within 100 +/- 10%	Hemoglobin, bilirubin, lipemia, protein, ascorbic acid, EDTA.2K, Sodium Heparin, Rheumatoid factor did not interfere.
Limit of Blank (LoB)	N/A (determined)	1.6 ng/mL
Limit of Detection (LoD)	N/A (determined)	2.6 ng/mL
Limit of Quantification (LoQ)	N/A (determined, 20% CV)	2.9 ng/mL
Reportable Range	N/A (defined)	4.0 - 120 ng/mL

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

Precision Studies (Intra-assay and Total):
- Three levels of pooled and spiked Na heparinized plasma, EDTA plasma, and serum specimens.
- 2 replicates per run, 2 times a day for 20 non-consecutive days for each specimen/reagent/instrument combination.
- Total of 40 runs and 80 determinants for each data set.
- Three data sets at each level for each specimen type.
- Provenance: Not explicitly stated, but typically these samples are prepared in-house or sourced from commercial vendors for method validation. It is not indicated if they are from a specific country or if they are retrospective/prospective clinical samples.
Linearity:
- Not specified, but linearity studies typically involve diluting samples to create a range of concentrations.
- Provenance: Not specified.
Correlation (Method Comparison):
- 156 unaltered serum specimens.
- Provenance: Not explicitly stated, but implied to be clinical human serum samples. No country of origin is mentioned, and it's not specified if they are retrospective or prospective.
Correlation (Matrix Comparison - Serum vs Na Heparinized Plasma):
- 115 unaltered specimens.
- Provenance: Not explicitly stated, but implied to be clinical human samples.
Correlation (Matrix Comparison - Serum vs EDTA Plasma):
- 115 unaltered specimens.
- Provenance: Not explicitly stated, but implied to be clinical human samples.
Cross Reactivity:
- Known quantities of cross-reactants spiked into serum specimens.
- Provenance: Not explicitly stated, but typically involves commercially available purified substances.
Reference Ranges:
- 233 samples.
- Provenance: Not explicitly stated, but implied to be human samples from a normal population.
Interference:
- Human specimens with added interfering substances (hemoglobin, bilirubin, triglycerides, human albumin, ascorbic acid, EDTA.2K, Sodium Heparin, Rheumatoid factor).
- Provenance: Not specified, but implied to be human biological samples.
Limit of Detection and Limit of Quantification:
- LoB: 60 measurements of 3 different blank specimens.
- LoD: 10 measurements of 6 low-level samples.
- LoQ: 10 measurements of 18 low-level samples.
- Provenance: Not specified, but likely prepared in-house or commercially sourced.

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

This device is an in vitro diagnostic (IVD) assay for quantitative measurement of a biomarker. For such devices, "ground truth" is typically established by:

Measurement by a validated reference method (e.g., the predicate device in the method comparison study).
Gravimetric preparation for linearity and analytical sensitivity.
Spiking studies for cross-reactivity and interference.

There is no mention of experts (like radiologists) being used to establish a subjective "ground truth" for the test set, as would be common for diagnostic imaging or AI-assisted diagnosis devices. The "ground truth" is the actual concentration of 25-OH Vitamin D as measured by the comparative method or by known analytical preparation.

4. Adjudication Method for the Test Set

Not applicable. As this is a quantitative chemical assay, not a subjective diagnostic interpretation, there is no need for expert adjudication methods like 2+1 or 3+1. The results are numerical values obtained from the instrument.

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 is relevant for diagnostic devices where human readers interpret results (e.g., medical images), and an AI might assist them. The ST AIA-PACK 25-OH Vitamin D is an automated in vitro diagnostic assay, so human interpretation is not involved in the primary measurement.

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

Yes, the performance characteristics studies (precision, linearity, correlation, cross-reactivity, interference, LoD/LoQ) represent the standalone algorithm only performance of the ST AIA-PACK 25-OH Vitamin D assay. The device itself performs the quantitative measurement without human intervention beyond sample loading and initiation.

7. The Type of Ground Truth Used

The ground truth for the various studies was established through:

Comparative Method: For method comparison, the DiaSorin 25-Hydroxyvitamin D 125I RIA Kit served as the comparative method.
Known Concentrations/Preparations:
- For linearity, samples were prepared with a known concentration range.
- For LoD/LoQ, samples were prepared at low known concentrations.
- For cross-reactivity, specific concentrations of potentially interfering substances were spiked into serum.
- For interference, known quantities of interfering substances were added to human specimens.
Statistical Analysis: Reference intervals were determined using statistical analysis of a population of samples.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of machine learning or AI algorithm development. This device is a traditional immunoassay, not an AI/ML-based device. Therefore, the concept of a training set as understood in AI is not directly applicable. The device's performance is based on its chemical reactions and detection system, which are designed and validated through analytical studies.

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

Since there is no "training set" in the AI/ML sense for this traditional immunoassay, this question is not applicable. The assay's "ground truth" is inherent to its analytical design and validation against reference methods and known concentrations.

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