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510(k) Data Aggregation
(162 days)
An enzyme immunoassay for the quantitative in vitro diagnostic measurement of active free cortisol (hydrocortisone and hydroxycorticosterone) in saliva. Measurements of cortisol are used in the diagnosis and treatment of disorders of the adrenal gland.
The DRG Salivary Cortisol ELISA KIT is based on the competition principle and the microplate separation. An unknown amount of Cortisol present in the sample and a fixed amount of Cortisol coniugated with horseradish peroxidase compete for the binding sites of mouse polyclonal Cortisol-antiserum coated onto the wells. After one hour incubation the microplate is washed to stop the competition reaction. After addition of the TMB substrate solution the concentration of Cortisol is inversely proportional to the optical density measured.
Here's an analysis of the provided text regarding the DRG Salivary Cortisol ELISA, focusing on acceptance criteria and study details:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied through the performance data presented, as explicit criteria (e.g., "must achieve X correlation") are not stated. The performance is reported against other commercially available methods or standard analytical techniques.
| Performance Metric | Implied Acceptance Criteria (Based on context) | Reported Device Performance |
|---|---|---|
| Method Comparison (vs. LIA) | High correlation (e.g., >0.85) | 0.872 (Study 1, n=114) |
| High correlation (e.g., >0.95) for expanded study | 0.9795 (Expanded Study 1, n=40) | |
| Method Comparison (vs. EIA) | High correlation (e.g., >0.90) | 0.936 (Study 2, n=72) |
| High correlation (e.g., >0.95) for expanded study | 0.9920 (Expanded Study 2, n=40) | |
| Method Comparison (vs. LC-MS) | High correlation (e.g., >0.85) | 0.89056 (Study 3, n=28) |
| Sensitivity (Lowest Detectable Limit) | As low as reasonably achievable for clinical utility (no specific numerical criterion given) | 0.537 ng/mL or 0.0537 ug/dl at 95% confidence limit |
| Specificity (Cross-Reactivity) | Low cross-reactivity with structurally similar compounds | Cortisol: 100%, Corticosterone: 29.00%, Cortisone: 3.00%, most others <1% or <0.5% |
| Intra-Assay Reproducibility (CV) | Low CV (typically <10-15%) | Data missing for this section in the provided text. |
| Inter-Assay Reproducibility (CV) | Low CV (typically <15-20%) | 7.47% (24.29 ng/mL mean), 5.82% (40.85 ng/mL mean) |
| Inter-Lot Reproducibility (CV) | Low CV (typically <15-20%) | Data missing for this section in the provided text. |
| Recovery | % Recovery within a generally accepted range (e.g., 80-120%) | Range of 90.1% to 108.8% across various spiked samples and concentrations. |
| Linearity (% Recovery) | % Recovery within a generally accepted range (e.g., 80-120%) | Average % Recovery: Sample 1: 107.0%, Sample 2: 99.1%, Sample 3: 97.5%. Range of % Recovery: Sample 1: 101.1-114.0%, Sample 2: 97.8-99.6%, Sample 3: 92.4-104.4% |
2. Sample Size Used for the Test Set and Data Provenance
The "test set" in this context refers to the samples used for method comparison and performance evaluation.
- Normal Range Study: 109 saliva samples. Adult male and female apparently healthy subjects, ages 20 to 80 years. Morning collection. (Provenance not specified, but likely domestic to DRG International, Inc. in NJ, USA, or related clinical sites). Prospective in nature.
- Method Comparison (Study 1 vs. LIA): 114 saliva samples. Subjects ages 40 to 70 years. (Provenance not specified). Retrospective implied as samples were "run".
- Method Comparison (Study 2 vs. EIA): 72 saliva samples. Men ages 40 to 70 years. (Provenance not specified). Retrospective implied.
- Method Comparison (Study 3 vs. LC-MS): 28 saliva samples. (Provenance not specified). Retrospective implied.
- Expanded Method Comparison (Study 1 vs. LIA): 40 saliva samples. Subjects ages 25-65 years. (Provenance not specified). Retrospective implied.
- Expanded Method Comparison (Study 2 vs. EIA): 40 saliva samples. Men and women ages 25-65 years. (Provenance not specified). Retrospective implied.
- Sensitivity: This is typically an in-vitro measurement using dilutions of known concentrations, not patient samples.
- Specificity: In-vitro evaluation of various steroid compounds.
- Reproducibility (Intra- and Inter-Assay): 4 saliva samples for intra-assay; commercial control samples for inter-assay.
- Reproducibility (Inter-Lot): 5 saliva samples.
- Recovery: 3 saliva samples with endogenous cortisol spiked with known amounts.
- Linearity: 3 saliva samples serially diluted.
The provenance regarding country of origin is not explicitly stated for any of the patient samples, but given the manufacturer's location, US-based samples are a reasonable assumption for a US regulatory submission. All studies appear to be retrospective analyses of collected samples.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of diagnostic device (ELISA kit for cortisol) doesn't typically rely on human expert interpretation of images or complex data for "ground truth" in the way an AI imaging device would. Instead, the ground truth for method comparison studies is established by:
- Reference method: Commercial LIA, EIA, and LC-MS methods. These methods are themselves established, and their results are treated as the "ground truth" for comparison.
- Known concentrations: For sensitivity, specificity, recovery, and linearity studies, known concentrations of cortisol or interfering substances are used.
Therefore, the concept of "experts establishing ground truth for the test set" is not directly applicable in the same way as for subjective diagnostic tasks. The performance is compared against existing, validated analytical methods.
4. Adjudication Method for the Test Set
Not applicable. As explained above, the "ground truth" for this type of device is established through comparison with recognized analytical methods or known sample concentrations, not through expert adjudication of subjective findings.
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 ELISA kit, a laboratory diagnostic test measuring a biochemical marker. It does not involve human "readers" or "AI assistance" in the interpretation of complex data (like medical images) where MRMC studies are relevant.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was Done
This is an in vitro diagnostic (IVD) kit. Its performance is inherently standalone, in that it provides a quantitative result based on the chemical reaction. There's no "human-in-the-loop" component in the interpretation of the raw assay signal (optical density) to derive the cortisol concentration once the assay is run and the standard curve is established. The device itself is the "algorithm only" (chemical reaction and measurement) to produce the result.
7. The Type of Ground Truth Used
The ground truth for the performance studies was primarily established by:
- Reference analytical methods: Commercially available LIA (Luminescence Immunoassay) and EIA (Enzyme Immunoassay) methods, and a reference LC-MS (Liquid Chromatography-Mass Spectrometry) method.
- Known concentrations: For sensitivity, specificity (known cross-reactants), recovery (spiked samples with known added cortisol), and linearity (serum samples with known dilutions).
8. The Sample Size for the Training Set
This document describes a premarket notification (510(k)) for a traditional IVD device. The language "training set" is typically associated with machine learning or AI algorithm development. For an ELISA kit, there isn't a "training set" in that sense. The kit's reagents, protocols, and standard curve parameters are developed through R&D experiments and optimization processes, but this is not typically referred to as a "training set" for an algorithm. The reported studies (method comparison, reproducibility, etc.) are essentially validation studies for the finalized product.
9. How the Ground Truth for the Training Set Was Established
As there isn't a "training set" for an algorithm in the AI sense, this question is not directly applicable. The "ground truth" for the development and optimization of the ELISA kit would involve established biochemical principles and highly controlled experiments using known concentrations of cortisol and other substances, likely following established laboratory practices for assay development.
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