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510(k) Data Aggregation
(441 days)
The Dimension Vista® Magnesium Flex® reagent cartridge (MG) method is an in vitro diagnostic test for the quantitative measurement of magnesium in human serum, plasma and urine on the Dimension Vista® System. Magnesium measurements are used in the diagnosis and treatment of hypomagnesemia (abnormally low plasma levels of magnesium) and hypermagnesemia (abnormally high plasma levels of magnesium).
The Dimension Vista® Chemistry 1 Calibrator (CHEM 1 CAL) is an in vitro diagnostic product for the calibration of Blood Urea Nitrogen (BUN),Calcium (CA), Cholesterol (CHOL), Creatinine (CRENCRE2), Glucose (GLU), Lactic Acid (LA), Magnesium (MG), Thyroxine (T4), Thyronine Uptake (TU) and Uric Acid (URCA) methods on the Dimension Vista® System.
CHEM 1 CAL is a liquid, frozen multi-analyte, bovine serum albumin based product used to calibrate blood urea nitrogen, calcium, cholesterol, creatinine, glucose, lactic acid, magnesium, thyroxine, thyronine uptake and uric acid. The kit consists of six vials, three vials of Calibrator A and three vials of Calibrator B.
The Dimension Vista® MG Flex® reagent cartridge uses a modified methylthymol blue (MTB) complexometric technique. MTB forms a blue complex with magnesium. Calcium interference is minimized by forming a complex between calcium and Ba-EGTA (chelating agent). The amount of MG-MTB complex formed is proportional to the magnesium concentration and is measured using a bichromatic (600 and 510 nm) endpoint technique.
The provided text describes the performance characteristics of the Dimension Vista® Magnesium Flex® reagent cartridge (MG) and the Dimension Vista® Chemistry 1 Calibrator (CHEM 1 CAL). The focus is on demonstrating substantial equivalence to predicate devices and meeting established clinical laboratory guidelines. However, the information is primarily focused on analytical performance rather than clinical effectiveness or diagnostic accuracy in specific patient populations.
Here's an attempt to extract the requested information, acknowledging that some categories may not be directly applicable or fully detailed given the nature of an in vitro diagnostic device's analytical validation.
1. Table of Acceptance Criteria and Reported Device Performance
Device: Dimension Vista® Magnesium Flex® reagent cartridge (MG) for quantitative measurement of magnesium.
| Performance Characteristic | Acceptance Criteria (Implicit from CLSI Guidelines and Study Design) | Reported Device Performance (MG Assay) |
|---|---|---|
| Method Comparison (Correlation) | High correlation (e.g., r > 0.975) with a legally marketed device; slope close to 1, intercept close to 0. | Serum: Slope: 1.10, Intercept: -0.15 mg/dL, Correlation Coefficient: 1.00 (vs. Beckman AU Magnesium assay) |
| Lithium Heparin Plasma: Slope: 1.05, Intercept: -0.01 mg/dL, Correlation Coefficient: 0.994 (vs. Beckman AU Magnesium assay) | ||
| Urine: Slope: 1.05, Intercept: 0.09 mg/dL, Correlation Coefficient: 0.995 (vs. Beckman AU Magnesium assay) | ||
| Precision (Repeatability & Within-Lab CV%) | Low Coefficient of Variation (CV%) as per CLSI EP05-A2. (Specific numerical criteria are not explicitly stated, but typical ranges for clinical assays are often <10% for low concentrations and <5% for higher concentrations). | Multiqual® Unassayed Control: Level 1 (1.1 mg/dL): Repeatability 4.8%, Within-Lab 5.1%; Level 2 (2.5 mg/dL): Repeatability 2.9%, Within-Lab 2.9%; Level 3 (4.0 mg/dL): Repeatability 1.9%, Within-Lab 2.4%. |
| Serum Pool: Pool 1 (1.9 mg/dL): Repeatability 3.4%, Within-Lab 3.7%; Pool 2 (4.5 mg/dL): Repeatability 1.8%, Within-Lab 2.1%. | ||
| Liquichek™ Urine Chemistry Control: Level 1 (7.0 mg/dL): Repeatability 1.2%, Within-Lab 1.5%. | ||
| Urine Pool: Pool 1 (7.3 mg/dL): Repeatability 1.0%, Within-Lab 1.3%. | ||
| Limit of Blank (LoB) | Consistent with claimed analytical sensitivity. | Serum: 0.002 mg/dL (Claimed: 0.2 mg/dL) |
| Urine: 0.2 mg/dL (Claimed: 0.2 mg/dL) | ||
| Limit of Detection (LoD) | Consistent with claimed analytical sensitivity, with false positives and negatives <5%. | Serum: 0.1 mg/dL (Claimed: 0.3 mg/dL) |
| Urine: 0.3 mg/dL (Claimed: 0.3 mg/dL) | ||
| Limit of Quantitation (LoQ) | Total Error (TE) ≤ 0.2 mg/dL. | Serum: 0.2 mg/dL (Supports claim of 0.3 mg/dL) |
| Urine: 0.3 mg/dL (Supports claim of 0.3 mg/dL) | ||
| Linearity | High correlation coefficient (close to 1), slope close to 1, intercept close to 0 across the assay range. | Serum: Range 0.4-11.4 mg/dL, Slope: 1.0109, Intercept: -0.0089, Corr Coef: 0.9998 |
| Urine: Range 0.3-11.4 mg/dL, Slope: 0.9997, Intercept: 0.0583, Corr Coef: 0.9986 |
2. Sample Sizes Used for the Test Set and Data Provenance
- Method Comparison Study:
- Serum and Plasma: 239 samples (combined total).
- Urine: 99 samples.
- Data Provenance: Retrospective, internal testing by Siemens Healthcare Diagnostics R&D personnel. The country of origin is not specified but implicitly assumed to be the location of the Siemens R&D facility.
- Precision Testing:
- Not reported as individual patient samples. Instead, it used control materials (Multiqual QC, Liquichek Urine QC) and pooled serum/urine samples.
- Each test material was run with two test samples over 20 days, in two separate runs.
- Limit of Blank/Detection (LoB/LoD):
- Serum (LoB/LoD): 96 determinations (based on 4 blank and 4 low-level samples, tested n=5 over 3 days, using 2 reagent lots).
- Urine (LoB/LoD): 96 determinations (based on 4 blank and 4 low-level samples, tested n=5 over 3 days, using 2 reagent lots).
- Limit of Quantitation (LoQ):
- Serum: 6 serum samples, 5 replicates (n=5) of each, with 2 reagent lots, over 3 days (total of 90 replicates per lot for serum).
- Urine: 6 urine samples, 5 replicates (n=5) of each, with 2 reagent lots, over 3 days (total of 90 replicates per lot for urine). Total 180 determinations for LoQ overall.
- Linearity Testing:
- Serum: 9 prepared samples (dilutions).
- Urine: 9 prepared samples (dilutions).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The term "ground truth" typically applies to diagnostic accuracy studies where expert consensus or a gold standard (e.g., pathology) is used to classify cases. For an in vitro diagnostic device measuring an analyte concentration, the "ground truth" for the test set is established by testing the same samples using a legally marketed predicate device (Beckman AU Magnesium assay in this case) or through reference materials (e.g., NIST SRM 929 for traceability of the calibrator).
- For Method Comparison: No external experts were explicitly mentioned for interpreting results. The comparison itself uses the Beckman AU Magnesium assay as the reference.
- For Calibrator Traceability: Magnesium is traceable to NIST SRM 929 (National Institute of Standards and Technology Standard Reference Material). This implies the ground truth for calibration levels is established by a highly reputable and standardized reference.
4. Adjudication Method for the Test Set
Adjudication methods (like 2+1, 3+1) are typically used in studies involving subjective interpretation (e.g., imaging) to resolve disagreements among human readers. This concept is not directly applicable to the analytical performance studies of a quantitative in vitro diagnostic device, where results are numerical values. Discrepancies in quantitative measurements would typically be investigated through repeat testing, instrument troubleshooting, or sample re-preparation, rather than expert adjudication of an interpretation.
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 assesses how human readers' diagnostic performance changes with and without AI assistance. The submitted device is a quantitative in vitro diagnostic reagent cartridge and calibrator, not an AI-powered diagnostic imaging or interpretation tool designed to assist human readers. Therefore, the concept of "human readers improve with AI vs without AI assistance" is not relevant to this device.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
While the device itself is a standalone analytical system (it measures magnesium concentrations automatically), the studies conducted are analytical performance studies, not a standalone diagnostic performance study in the sense of an algorithm interpreting clinical data to make a diagnosis without human input. The output is a quantitative measure of magnesium, which a clinician then interprets in the context of a patient's overall health.
The device itself represents "algorithm only" performance in the sense that it mechanically and biochemically performs the assay without human interpretation during the measurement process. The analytical studies (precision, linearity, LoD, etc.) demonstrate this standalone analytical performance.
7. The Type of Ground Truth Used
- For Method Comparison: The "ground truth" was established by comparison with a legally marketed predicate device, the Beckman AU Magnesium assay (K981743). This is a common approach for demonstrating substantial equivalence for in vitro diagnostics.
- For Calibrator Traceability: The ground truth for magnesium levels in the calibrator is traced to NIST SRM 929, which is a primary reference standard. This provides a highly accurate and standardized "ground truth" for the calibrator values.
- For Studies like LoB, LoD, LoQ, Linearity, Precision: The ground truth for these analytical performance characteristics is derived from statistical analysis of repeated measurements against well-defined samples (e.g., blank samples, low-level samples, serially diluted samples) and comparison to established CLSI guidelines for acceptable performance.
8. The Sample Size for the Training Set
The document does not specify a "training set" in the context of machine learning or AI algorithm development. This device is a traditional in vitro diagnostic reagent, relying on a biochemical reaction and photometric measurement, not a machine learning model that requires a discrete training phase. Therefore, the concept of a separate training set is not applicable here. The development and optimization of the reagent formulation and instrument settings would have involved extensive R&D, but this is not typically characterized as a "training set" in the AI/ML sense.
9. How the Ground Truth for the Training Set Was Established
As noted above, there is no "training set" in the AI/ML sense for this device. The physical and chemical properties of magnesium and the methylthymol blue reaction are the underlying "truth" guiding the development of the assay. Calibrator values leverage traceability to NIST SRM 929.
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