(109 days)
The BioPlex 2200 25-OH Vitamin D Kit is a multiplex flow competitive immunoassay intended for the quantitative determination of 25-hydroxyvitamin D in human serum. The BioPlex 2200 25-OH Vitamin D assay is to be used as an aid in the assessment of vitamin D sufficiency.
The BioPlex 2200 25-OH Vitamin D kit is intended for use with the Bio-Rad BioPlex 2200 System.
BioPlex 2200 25-OH Vitamin D kit includes the following components:
- One (1) 10 mL vial of Bead Set containing dyed beads coated with anti-25-0H ● Vitamin D antibody (sheep), an Internal Standard bead (ISB), and a Serum Verification bead (SVB) in buffer with protein stabilizers (bovine). ProClin 950 (
The BioPlex 2200 25-OH Vitamin D Kit is a multiplex flow competitive immunoassay intended for the quantitative determination of 25-hydroxyvitamin D in human serum, to be used as an aid in the assessment of vitamin D sufficiency. The device underwent a 510(k) submission, K180577, to demonstrate substantial equivalence to its predicate device, BioPlex 2200 25-OH Vitamin D Kit (K141114). The new kit has been modified by re-assigning calibrators and standardizing the assay in accordance with the Vitamin D Standardization Program (VDSP).
Here's an analysis of the acceptance criteria and the studies performed:
1. Table of Acceptance Criteria and Reported Device Performance:
The document primarily focuses on demonstrating substantial equivalence to a predicate device and adherence to CLSI guidelines for analytical performance. Therefore, "acceptance criteria" for specific performance metrics are often implied by the standards set forth in these guidelines and the performance of the predicate device, rather than explicit numerical targets stated as acceptance criteria in the summary. However, we can infer some criteria from the presented data.
| Acceptance Criteria (Inferred/Implied) | Reported Device Performance (BioPlex 2200 25-OH Vitamin D Kit) |
|---|---|
| Precision | |
| Within-run, Between-run, Between-day, Total precision within acceptable limits (CLSI EP5-A3) | Demonstrated with %CVs ranging from 3.0% to 10.7% depending on concentration and type of precision. Most values below 10%. |
| Reproducibility | |
| Reproducibility across runs/days within acceptable limits (CLSI EP15-A3) | Demonstrated with %CVs ranging from 3.5% to 10.0% depending on concentration and type of precision. |
| Linearity/Reportable Range | |
| Linearity across the measuring range (CLSI EP06-A) | Demonstrated with good linear regression (e.g., slope 1.0002, r² 0.9956 for one example). Reportable range: 7.0 – 160.0 ng/mL. |
| Traceability | |
| Traceable to ID-LC/MS/MS RMP and NIST SRM 2972a | Directly stated: "traceable to the ID-LC/MS/MS 25(OH) vitamin D Reference Method Procedure (RMP) that is traceable to the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2972a." |
| Kit Stability | |
| Unopened: 24 months at 2 to 8°C | 24 months or until expiration date. |
| Open: 60 days | 60 days. |
| Sample Stability | |
| Fresh (2 to 8°C): 7 days | 7 days. |
| Frozen (-20 or -70°C): 24 months | 24 months. |
| Freeze-thaw cycles: acceptable | Up to 5 cycles at -20°C, 2 cycles at -70°C. |
| Detection Limits (LoB, LoD, LoQ) | |
| LoB, LoD, LoQ established (CLSI EP17-A2) | LoB: 5.4 ng/mL, LoD: 7.0 ng/mL, LoQ: 7.0 ng/mL. |
| Analytical Specificity (Interference) | |
| No significant interference from tested substances at specified concentrations (CLSI EP07-A2) | "No interference was observed with any of the substances tested" at the maximum levels listed (e.g., Hemoglobin 100%). Normalized 25(OH) D2 cross-reactivity is 103% (to 25(OH)D3). |
| Method Comparison with Predicate Device | |
| Good correlation and agreement with predicate device (CLSI EP09-A3) | Slope: 1.048 (95% CI: 1.009 - 1.088), Intercept: -0.885 (95% CI: -2.211 - 0.441), Correlation Coefficient (r): 0.987 (95% CI: 0.983 - 0.990). |
| Method Comparison to Reference Method (VDSP-certified RMP) | |
| Good correlation and agreement with VDSP RMP | Slope: 0.993 (95% CI: 0.913 - 1.073), Intercept: -0.775 (95% CI: -2.705 - 1.155), Correlation Coefficient (r): 0.949 (95% CI: 0.927 - 0.964). |
| Bias at Medical Decision Levels | |
| Acceptable bias at key medical decision points (20, 30, 100 ng/mL) | Mean bias: -7.3% at 20 ng/mL, -0.2% at 30 ng/mL, 3.5% at 100 ng/mL. Overall mean bias: 1.0%. |
| Expected Values/Reference Range | |
| Established from a healthy population (CLSI EP28-A3c) | Mean: 31.9 ng/mL, Median: 29.2 ng/mL, 2.5th – 97.5th percentile: 14.0 – 76.3 ng/mL (based on 288 healthy donors). |
2. Sample size used for the test set and data provenance:
- Precision Studies (CLSI EP5-A3):
- Sample Size: 6 human serum samples and 2 control levels. Each tested in duplicate per run, on two runs per day over 20 days (N=80 results per sample/control).
- Data Provenance: Not explicitly stated (e.g., country of origin, retrospective/prospective), but it was human serum from a "panel".
- Reproducibility Studies (CLSI EP15-A3):
- Sample Size: 8 panel members (serum matrix and QC controls), tested in replicates of two on two runs per day over five days (20 replicates per panel member).
- Data Provenance: Performed at "one (1) US testing facility." Not explicitly stated if retrospective or prospective, or specific origin of serum matrix.
- Linearity/Assay Reportable Range (CLSI EP06-A):
- Sample Size: Five high patient serum samples initially, serially diluted. Each sample and dilution evaluated in replicates of four.
- Data Provenance: Not explicitly stated.
- Detection Limits (LoB, LoD, LoQ) (CLSI EP17-A2):
- LoB: Five blank samples, tested in 4 replicates per day for 5 days (100 data points per reagent lot).
- LoD: Six human samples with low 25-OH vitamin D, tested in 10 replicates per day for five days (50 data points per sample per reagent lot).
- Data Provenance: Not explicitly stated.
- Interfering Substances (CLSI EP07-A2):
- Sample Size: Not explicitly stated for number of samples, but "human serum pools" were used.
- Data Provenance: Not explicitly stated.
- Cross-Reactivity (CLSI EP17-A2):
- Sample Size: 2 human serum pools. Nine cross-reactants were spiked into these pools. Spiked and non-spiked samples evaluated in replicates of five.
- Data Provenance: Not explicitly stated.
- Method Comparison with Predicate Device (CLSI EP09-A3):
- Sample Size: 201 human samples (182 unaltered, 19 spiked with 25-hydroxyvitamin D3).
- Data Provenance: Not explicitly stated (e.g., country of origin, retrospective/prospective).
- Method Comparison to Reference Method (VDSP):
- Sample Size: 120 native single donor patient serum samples.
- Data Provenance: "reference sample set provided by the Vitamin D Standardization and Certification Program with assigned values by the RMP at CDC, independent from the samples used for standardization." This indicates a high-quality, external reference set. The origin of the patient samples themselves is not specified beyond "native single donor patient serum samples".
- Bias at Vitamin D Medical Decision Levels:
- Sample Size: 303 samples overall for bias analysis, with specific numbers at each decision range (e.g., 7 for 19-21 ng/mL, 20 for 29-31 ng/mL, 6 for 95-105 ng/mL).
- Data Provenance: Presumably a subset or re-analysis of samples from the method comparison studies.
- Expected Values/Reference Range (CLSI EP28-A3c):
- Sample Size: 288 samples from "apparently healthy donors" (161 males, 127 females).
- Data Provenance: Samples collected from "three regions (Northern, Central, and Southern) in the US" in spring, summer, and winter. Included African Americans, Hispanics, and Caucasians. This is prospective collection for establishing a reference range.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
This device is an in vitro diagnostic (IVD) quantitative assay for a biomarker (25-OH Vitamin D). The "ground truth" for such devices is established through highly accurate and standardized analytical methods.
- For the Method Comparison to Reference Method, the ground truth was established by the Vitamin D Standardization and Certification Program (VDSP) using an ID-LC/MS/MS Reference Method Procedure (RMP) at CDC. This RMP is traceable to the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 2972a. These are highly qualified and internationally recognized reference methods and institutions for chemical measurements, representing the gold standard in analytical chemistry. It is not about expert consensus on interpretations, but rather expert execution and certification of analytical accuracy.
- For other studies (precision, linearity, etc.), the "ground truth" is typically the measured value itself by the reference method or the assigned value of controls and calibrators, which are also traceable to established analytical standards.
4. Adjudication method for the test set:
Not applicable in the conventional sense involving multiple human readers and an adjudication process. This is a quantitative IVD device where sample values are measured against established reference methods and standards, not interpreted by experts in a clinical imaging or diagnostic context that would require adjudication.
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 is a laboratory diagnostic assay, not an AI-assisted diagnostic tool that involves human readers interpreting cases.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
This device performs as a standalone automated multiplex flow competitive immunoassay on the Bio-Rad BioPlex 2200 System. Its performance characteristics (precision, linearity, LLoQ, etc.) were evaluated directly without human intervention in the measurement process, representing a "standalone" analytical performance assessment. However, it's not an "algorithm only" device in the sense of AI; it's a chemical assay. The output is a quantitative measure of 25-OH Vitamin D concentration.
7. The type of ground truth used:
- For method comparison, the ground truth for the 120 samples was assigned values by the RMP at CDC, provided by the Vitamin D Standardization and Certification Program (VDSP). This is a highly accurate and externally certified analytical ground truth.
- For other analytical validation studies, the ground truth is established through internal standards, traceable calibrators, and reference materials specified by CLSI guidelines and traceable to NIST SRM 2972a.
8. The sample size for the training set:
- This submission describes performance validation for a modified in vitro diagnostic kit. The "training set" concept (as used in machine learning) is not directly applicable here. The device itself (the BioPlex 2200 system and its reagents) has established methodologies.
- The document states that Bio-Rad "modified the kit by re-assigning the calibrators and standardizing the assay in accordance with the Vitamin D Standardization Program (VDSP)." This implies that Bio-Rad used samples and measurements to establish these new calibrator assignments and standardization. However, the specific size and nature of such internal development/calibration "training" sets are not detailed in this 510(k) summary. The summary focuses on the validation of the finalized device.
9. How the ground truth for the training set was established:
- Again, the concept of a "training set" for an IVD kit often refers to the samples used during development and calibration. For this device, the key aspect of this "ground truth" for the modified kit is its standardization in accordance with the Vitamin D Standardization Program (VDSP). This means that the calibrators and ultimately the assay's measurements are referenced to the same highly accurate ID-LC/MS/MS RMP and NIST SRM 2972a that were used to establish the ground truth for the external validation sample sets. This ensures analytical accuracy and comparability across different methods and laboratories. The actual process of selecting and assigning values to the new calibrators would involve measuring reference materials and/or highly characterized samples using the VDSP-traceable methods.
§ 862.1825 Vitamin D test system.
(a)
Identification. A vitamin D test system is a device intended for use in clinical laboratories for the quantitative determination of 25-hydroxyvitamin D (25-OH-D) and other hydroxylated metabolites of vitamin D in serum or plasma to be used in the assessment of vitamin D sufficiency.(b)
Classification. Class II (special controls). Vitamin D test systems must comply with the following special controls:(1) Labeling in conformance with 21 CFR 809.10 and
(2) Compliance with existing standards of the National Committee on Clinical Laboratory Standards.