(8 days)
The Elecsys Cortisol is an immunoassay for the in-vitro quantitative determination of cortisol in serum, plasma, urine and saliva. The determination of cortisol is used for the recognition and treatment of functional disorders of the adrenal gland. The electrochemiluminescence immunoassay "ECLIA" is intended for use on the Roche Elecsys 1010/2010 and MODULAR ANALYTICS E170 (Elecsys module) immunoassay analyzers.
The Elecsys Cortisol Assay is a two step sandwich immunoassay with streptavidin microparticles and electrochemiluminescence detection. Results are determined using a calibration curve that is generated specifically on each instrument by a 2 point calibration and a master curve provided with the reagent bar code.
Here's an analysis of the acceptance criteria and supporting study for the Elecsys® Cortisol Immunoassay System, based on the provided 510(k) summary:
Device: Elecsys® Cortisol Immunoassay System
1. Table of Acceptance Criteria and Reported Device Performance
The submission focuses on demonstrating substantial equivalence to a predicate device rather than setting explicit acceptance criteria in the way a clinical trial might for a new drug. Instead, it provides performance characteristics of the new device and compares them to the predicate, implying that performance comparable to the predicate (and within acceptable analytical ranges for this type of test) is the "acceptance criteria."
| Feature | Acceptance Criteria (Implied by Predicate Performance / Clinical Acceptability for Cortisol Assays) | Reported Device Performance (Elecsys Cortisol Immunoassay) |
|---|---|---|
| Precision | Comparable to or better than the predicate's intra-assay CVs (4.25% CV @ 1.591 ug/dL, 4.97% CV @ 0.702 ug/dL, 5.73% CV @ 0.188 ug/dL, 5.28% CV @ 0.115 ug/dL) and generally acceptable for quantitative immunoassays. | Within-run (E2010): |
| 6.1% CV @ 0.170 ug/dL | ||
| 2.7% CV @ 0.417 ug/dL | ||
| 4.0% CV @ 0.547 ug/dL | ||
| 1.5% CV @ 0.576 ug/dL | ||
| 2.8% CV @ 0.718 ug/dL | ||
| Between Run: | ||
| 37.1% CV @ 0.034 ug/dL (Note: sample concentration below functional claim of assay) | ||
| 7.2% CV @ 0.280 ug/dL | ||
| 6.2% CV @ 0.613 ug/dL | ||
| 4.9% CV @ 1.25 ug/dL | ||
| 4.1% CV @ 1.54 ug/dL | ||
| Functional Sensitivity | Clinically relevant detection limit for cortisol in saliva. The predicate did not explicitly state this, but a value 0.9) and good agreement (slope close to 1, intercept close to 0) between the new device and the predicate device across a clinically relevant range of concentrations. | Elecsys Cortisol vs. Salimetrics: |
| Slope = 0.90 (95% CI 0.87-0.94) | ||
| Intercept= 1.71 (95% CI 1.47-1.96) | ||
| r= 0.942 | ||
| Measuring Range | Adequate to cover both normal and pathological cortisol levels. For Elecsys, the range is 1.00 - 1750 nmol/L (0.036 - 63 ug/dL). The predicate's calibrator range was 0.007-1.800 ug/dl. The Elecsys measured range is significantly wider. | 1.00 - 1750 nmol/L (0.036 - 63 ug/dL) |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size (Method Comparison): 326 samples
- Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective. It is implied to be a direct comparison of patient samples run on both systems.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
This type of immunoassay does not typically involve expert readers for establishing ground truth in the way medical imaging devices do. The "ground truth" for the method comparison is the measurement obtained from the predicate device (Salimetrics HS Salivary Cortisol Enzyme). The results are compared statistically, not against a human interpretation.
4. Adjudication Method for the Test Set
Not applicable for this type of quantitative immunoassay comparison. Adjudication is typically used in subjective interpretation tasks (e.g., radiology readings) to reconcile differing expert opinions. Here, the comparison is direct numerical data.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No, an MRMC study was not done. MRMC studies are relevant for devices that involve human interpretation, often assisted by AI, to assess the impact of the device on human performance. This is a standalone quantitative assay.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
Yes, the device is a standalone quantitative immunoassay platform. Its performance characteristics (precision, sensitivity, method comparison) are inherently "standalone," meaning they represent the device's performance without human interpretive intervention.
7. The Type of Ground Truth Used
For the method comparison, the "ground truth" was the results obtained from the predicate device (Salimetrics HS Salivary Cortisol Enzyme). For other performance metrics like precision and sensitivity, the ground truth is established through standard laboratory practices using known controls and calibrators, often with traceability to a reference method (e.g., ID-MS for the Elecsys Cortisol).
8. The Sample Size for the Training Set
The document does not specify a separate "training set" in the context of machine learning or AI. For immunoassay development, there are typically reagent optimization phases and validation studies that involve numerous samples and controls, but these are not usually referred to as "training sets" in the same way as in AI/ML development. The provided data for method comparison is a validation dataset.
9. How the Ground Truth for the Training Set Was Established
As there's no explicitly defined "training set" in the AI/ML sense, this question is not directly applicable. If considering the development and optimization of the immunoassay itself, the "ground truth" would be established using reference materials, calibrators, and possibly samples with known cortisol concentrations (e.g., measured by ID-MS or another highly accurate reference method).
§ 862.1205 Cortisol (hydrocortisone and hydroxycorticosterone) test system.
(a)
Identification. A cortisol (hydrocortisone and hydroxycorticosterone) test system is a device intended to measure the cortisol hormones secreted by the adrenal gland in plasma and urine. Measurements of cortisol are used in the diagnosis and treatment of disorders of the adrenal gland.(b)
Classification. Class II.