(110 days)
The 1,25-Dihydroxyvitamin D 1251 RIA is a competitive equilibrium radioimmunoassay intended for the quantitative determination of 1,25 dihydroxyvitamin D (1,25-(OH)2-D) in human serum or EDTA plasma to be used to assess 1,25-(OH)2-D deficiency associated with renal disease. Assay results should be used in conjunction with other clinical and laboratory data to assist the clinician in making individual patient management decisions in adult populations.
The 1,25-Dihydroxyvitamin D 1251 RIA is a competitive radioimmunoassay intended for the quantitative determination of 1,25 Dihydroxyvitamin D (1,25-(OH)2-D) in human serum or EDTA plasma. The assay consists of a two-step procedure. Serum or plasma patient samples as well as standards and kit controls are first extracted with acetonitrile to free the 1,25-(OH)2 vitamin D2 and D3 from their vitamin D binding protein, and remove lipids that might interfere with the assay. The metabolites are then extracted by column chromatography on C18OH silica cartridges using a series of organic solvent washes. Following the extraction, the treated samples are assayed using a competitive radioimmunassay procedure. The primary antibody (rabbit anti-1,25-(OH)2 vitamin D) is highly specific for both 1,25(OH)2 vitamin D3 and 1,25(OH)2.vitamin D2. Vitamin D) is inghty specific for both 1,25(011)2 (011)2 vitamin D tracer Daring the binding sites on the primary antibody. Separation of bound and unbound vitamin D2 or D3 is accomplished using a goat anti-rabbit (GAR) polyethylene glycol precipitating complex. After an incubation and centrifugation, sample precipitates are proofitaing complex. The amount of radioactivity in the precipitate is inversely proportional to the concentration of 1,25-(OH)2 vitamin D in the sample. Values are proportional to the coma standard curve of known calibrators and expressed as pg/ml.
Here's an analysis of the provided text regarding the acceptance criteria and study for the 1,25-Dihydroxyvitamin D 1251 RIA Kit.
1. Table of Acceptance Criteria and Reported Device Performance
The document doesn't explicitly state "acceptance criteria" in a typical quantitative pass/fail format. Instead, it presents performance characteristics (reproducibility and distinct reference ranges) that effectively serve as evidence of the device's suitability for its intended use. For this exercise, I will infer the implied acceptance criteria from the reported performance.
| Performance Metric | Inferred Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Reference Ranges | Distinct 1,25-(OH)2-D values for healthy normals and End-Stage Renal Disease (ESRD) patients. | Normals (n=123): Mean 43.9 pg/mL, Range 19.8-68.0 pg/mL (2 SD of 24.1) |
| ESRDs (n=87): Range 1.6-17.3 pg/mL | ||
| Conclusion: Reference ranges are "fully distinct," indicating effective discrimination. | ||
| Sample Equivalency (Frozen vs. Fresh) | No statistically significant difference (p > 0.05) between frozen and fresh samples. | Normals (Frozen n=72, Fresh n=51): Mean Frozen 43.2, Mean Fresh 44.8, ANOVA p=0.49 |
| ESRDs (Frozen n=70, Fresh n=17): Mean Frozen 6.1, Mean Fresh 5.3, ANOVA p=0.29 | ||
| Conclusion: No significant difference. | ||
| Reproducibility (DiaSorin Lab) | Acceptable Within-run, Between Day, and Total %CVs for low, mid, and high concentration samples. | Low (25.8 pg/mL): Within-run %CV 6.8, Between Day %CV 14.6, Total %CV 15.3 |
| Mid (41.3 pg/mL): Within-run %CV 7.7, Between Day %CV 11.1, Total %CV 12.3 | ||
| High (105.2 pg/mL): Within-run %CV 11.3, Between Day %CV 11.2, Total %CV 13.7 | ||
| Reproducibility (Clinical Trial - Human Serum Samples) | Acceptable %CVs for low, mid, and high concentration human serum-based samples across multiple sites. | Low (24.2 pg/mL): %CV 16.2 |
| Mid (41.0 pg/mL): %CV 14.1 | ||
| High (97.7 pg/mL): %CV 11.6 | ||
| Reproducibility (Clinical Trial - Kit Controls) | Acceptable %CVs for Kit Control 1 and Kit Control 2 across multiple sites. | Kit Control 1 (25.6 pg/mL): %CV 13.7 (total across 3 sites) |
| Kit Control 2 (65.2 pg/mL): %CV 12.4 (total across 3 sites) |
2. Sample Sizes Used for the Test Set and Data Provenance
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Reference Ranges Study (Implicit Test Set):
- Normals: 123
- ESRDs: 87
- Data Provenance: Clinical trial conducted at "three independent clinical laboratories." The country of origin is not specified, but the submission is to the FDA, suggesting it's likely US-based or at least compliant with US regulatory standards. The data is prospective, collected during the clinical trial for the purpose of demonstrating the device's performance.
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Sample Equivalency Study (Frozen vs. Fresh):
- Normals: 72 (Frozen) + 51 (Fresh) = 123
- ESRDs: 70 (Frozen) + 17 (Fresh) = 87
- Data Provenance: Same as above, presumed prospective from the clinical trial.
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Reproducibility Studies (Test Sets for Precision):
- DiaSorin Lab: 25 per sample type (Low, Mid, High)
- Clinical Trial (Human Serum Samples): 16 per sample type (Low, Mid, High)
- Clinical Trial (Kit Controls): 19 for Control 1, 18 for Control 2 (across three sites).
- Data Provenance: DiaSorin Inc. laboratory (in-house) and three independent clinical laboratories (clinical trial). All are prospective data generation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of in-vitro diagnostic (IVD) device, which quantitatively measures a biomarker, does not typically rely on "experts" to establish ground truth in the same way an imaging AI might. Instead, the "ground truth" for quantitative assays is the assigned concentration of the analyte in calibrators and controls, and the known clinical status (healthy vs. ESRD) of the patient samples.
- Number of 'Experts': Not applicable in the sense of human interpretation.
- Qualifications of Experts: Not applicable. The "ground truth" is derived from the established methods of preparing and characterizing assay standards and controls, and clinical diagnosis of the patient populations.
4. Adjudication Method for the Test Set
Not applicable. As a quantitative immunoassay, there is no subjective adjudication of results. The results are numerical values. The clinical status of patients (normality vs. ESRD) is presumably based on standard diagnostic criteria, not an adjudication process specified here for the device's output.
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 an in-vitro diagnostic assay (RIA kit) for measuring a biomarker, not an imaging or interpretive AI device that assists human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, this is effectively a standalone performance study. The device (RIA kit) produces quantitative results (pg/mL of 1,25-(OH)2-D) directly. The performance studies (reference ranges, equivalency, reproducibility) demonstrate the accuracy and precision of these direct measurements. While clinicians use these results for patient management, the device itself operates "standalone" in providing the measurement.
7. The Type of Ground Truth Used
The ground truth for this device's performance assessment relies on:
- Assigned Concentrations: For calibrators and controls, the "ground truth" is the known, pre-defined concentration of 1,25-(OH)2-D in these materials.
- Clinical Diagnosis: For the reference range studies, the "ground truth" for patient populations is their established clinical status (e.g., "apparently healthy normal donors" vs. "patients with end-stage renal disease (ESRD)"). This clinical diagnosis serves as the label for demonstrating the device's ability to discriminate between these groups.
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. This is a traditional IVD device, not an AI/ML product. The assay's parameters (e.g., antibody specificity, incubation times, standard curve generation) are developed and optimized through assay development rather than through a formal "training set" as understood in AI. The standard curve itself, derived from five levels of human serum-based standards, could be considered analogous to a small training set for calibrating each run, but it's not a general training set for an algorithm.
9. How the Ground Truth for the Training Set Was Established
Not applicable in the AI/ML context. For the instrument's calibration (which is similar to training its measurement curve), the ground truth for the five serum-based standards is established by precisely formulating them with known concentrations of 1,25-(OH)2-D or through comparison to a reference method, although the latter is not detailed here.
§ 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.