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510(k) Data Aggregation
(61 days)
The Stratus® CS Acute Care™ NT-proBNP method (pBNP) is an in vitro diagnostic assay for the quantitative determination of N-terminal pro-brain natriuretic peptide (NT-proBNP) in buman plasma. In individuals suspected of having congestive heart failure (CHF), measurements of NT-proBNP are used as an aid in the diagnosis and assessment of severity. The test is further indicated for the risk stratification of patients with acute coronary syndrome and heart failure.
The NT-proBNP Calibrator (pBNP CalPak) is an in vitro diagnostic product intended to be used for calibration of the NT-proBNP method on the Stratus® CS analyzer.
The NT-proBNP Dilution Pak (DilPak) is an in vitro diagnostic product intended to be used for dilution of the NT-proBNP Method on the Stratus® CS analyzer.
The Stratus® CS Acute Care™ NT-proBNP method is a two-site sandwich assay based upon solid phase Radial Partition Immunoassav (RPIA) technology. In this procedure, dendrimer linked polyclonal antibody is added to the center portion of a square piece of glass fiber paper in the pBNP TestPak. This antibody recognizes a distinct antigenic site on the NT-proBNP molecule. Sample is then added onto the paper where it reacts with the immobilized antibody. After a short incubation, a conjugate consisting of enzyme-labeled polvclonal antibody directed against a second distinct antigenic site on the NT-proBNP molecule is pipetted onto the reaction zone of the paper. During this second incubation period, enzyme-labeled antibody reacts with the bound NT-proBNP , forming an antibody-antigen-labeled antibody sandwich. The unbound labeled antibody is later eluted from the field of view of the Stratus® CS analyzer by applying a substrate wash solution to the center of the reaction zone. By including substrate for the enzyme within the wash solution, initiation of enzyme activity occurs simultaneously with the wash. The enzymatic rate of the bound fraction increases directly with the concentration of NT-proBNP in the sample. The reaction rate can then be measured by an optical system that monitors the reaction rate via front surface fluorescence. All data analysis functions are performed by the microprocessor within the analyzer.
Here's a summary of the acceptance criteria and study details for the Dade Behring Stratus® CS Acute Care™ NT-proBNP TestPak assay, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The device's performance was deemed "substantially equivalent" to the predicate device (Roche Diagnostics Elecsys® proBNP immunoassay). The acceptance criteria are implicitly defined by demonstrating comparable performance across various analytical and clinical metrics.
| Feature / Acceptance Criteria (Implicit) | Reported Device Performance (Stratus® CS Acute Care™ pBNP) | Comparison to Predicate (Roche Elecsys® proBNP) |
|---|---|---|
| Intended Use | For the in vitro quantitative determination of N-terminal pro-brain natriuretic peptide in human plasma as an aid in the diagnosis and assessment of severity of individuals suspected of having congestive heart failure. The test is further indicated for the risk stratification of patients with acute coronary syndrome and heart failure. | Similar intended use, with slight wording differences. The key clinical applications of diagnosis, severity assessment, and risk stratification are consistent. |
| Reportable Range | 15- 20,000 pg/mL | Predicate: 5 - 35,000 pg/mL. The Stratus® CS range is slightly narrower, but still overlaps significantly for clinical utility. |
| Analytical Sensitivity | 15 pg/mL | Predicate: 5 pg/mL. Stratus® CS has a slightly higher lower detection limit, but still within a clinically relevant range. |
| Functional Sensitivity | < 50 pg/mL | Predicate: < 50 pg/mL. Performance is equivalent. |
| Cut-off Values (for clinical use) | 125 pg/mL for patients < 75 years; 450 pg/mL for patients ≥ 75 years | Predicate: 125 pg/mL for patients < 75 years; 450 pg/mL for patients ≥ 75 years. Performance is equivalent; the document states, "The high level of equivalence... justifies using the same cutoffs." |
| Clinical Performance (Sensitivity, Males < 75 yrs) | 90% (84 – 95 CI) | Predicate: 91% (86 – 96 CI). Very similar. |
| Clinical Performance (Specificity, Males < 75 yrs) | 92% (86 – 98 CI) | Predicate: 93% (87 – 98 CI). Very similar. |
| Clinical Performance (Sensitivity, Females < 75 yrs) | 84% (74-94 CI) | Predicate: 84% (74-94 CI). Identical. |
| Clinical Performance (Specificity, Females < 75 yrs) | 92% (87-97 CI) | Predicate: 94% (90-99 CI). Very similar. |
| Method Comparison (Slope vs. Predicate) | 0.96 | Indicating good agreement (close to 1). |
| Method Comparison (Correlation Coefficient vs. Predicate) | 0.99 | Indicating very strong linear correlation. |
| Reproducibility (Within-Run Precision, %CV) | Pool 1: 4.2%; Pool 2: 3.2%; Pool 3: 2.6%; Level 1: 4.9%; Level 2: 2.1% | Not directly compared to a specific predicate value in the document, but these values are generally considered good for diagnostic assays. |
| Reproducibility (Total Precision, %CV) | Pool 1: 5.1%; Pool 2: 3.2%; Pool 3: 2.6%; Level 1: 4.9%; Level 2: 3.0% | Not directly compared to a specific predicate value in the document, but these values are generally considered good for diagnostic assays. |
| Lithium Heparin vs. Sodium Heparin Agreement (Slope) | 1.00 | Demonstrates excellent agreement between different heparin types, indicating flexibility in sample collection. |
| Lithium Heparin vs. Sodium Heparin Agreement (Correlation Coefficient) | 0.999 | Demonstrates excellent agreement. |
2. Sample Size Used for the Test Set and Data Provenance
- Clinical Performance Test Set:
- Reference Study Group (without CHF): 308 individuals (163 Women, 145 Men).
- Disease Study Group (with CHF): 234 patients (70 women, 164 men).
- Provenance: Data used for clinical values were generated at the University of Maryland Medical Center. The document does not explicitly state if the data was retrospective or prospective, but clinical studies for such assays are typically prospective or involve collecting new samples from a defined population.
- Method Comparison Test Set:
- Sample Size: 481 heparinized plasma patient samples.
- Provenance: Not explicitly stated, but likely from the same clinical study background as the clinical performance data, given the reference to "method comparison and reference interval data sets generated at the University of Maryland Medical Center."
- Lithium Heparin vs. Sodium Heparin Test Set:
- Sample Size: 19 samples.
- Provenance: Not explicitly stated.
- Reproducibility Test Set:
- Sample Size: Multiple human plasma pools (n=3) and commercial controls (n=2). Each level was analyzed in duplicate once per day for 20 days (total of 40 measurements per level).
- Provenance: Laboratory testing according to NCCLS guidelines.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
- Clinical Performance: The ground truth for "congestive heart failure (CHF)" and "without congestive heart failure" was established by diagnosis. The document does not specify the number or qualifications of medical experts who made these diagnoses. However, it states that the "Disease Study Group" consisted of "patients diagnosed with congestive heart failure," implying physician diagnosis as the ground truth.
- Analytical Performance: Analytical ground truth for NT-proBNP concentrations in the test samples was established by the predicate device (Roche Elecsys® proBNP immunoassay) and verified against known standards for reproducibility and linearity studies.
4. Adjudication Method for the Test Set
- Clinical Performance: Not explicitly mentioned, but the ground truth (diagnosis of CHF) would typically be established by clinical consensus or accepted diagnostic criteria by treating physicians. There is no mention of a separate adjudication panel for the diagnostic status of the patients.
- Analytical Performance: Not applicable, as it involves comparison to an existing, validated method and instrument readings.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is an in vitro diagnostic assay that automates the measurement of a biomarker from a biological sample. It does not involve human readers interpreting images or data in a way that an MRMC study would be applicable. The comparison is between the performance of two automated assay systems.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
Yes, this was a standalone performance study of the algorithm (the immunoassay method) as a diagnostic test. The device provides quantitative measurements of NT-proBNP directly. The performance metrics (sensitivity, specificity, method comparison, reproducibility) are measures of the assay's performance on its own. Human clinicians then use these quantitative results for diagnosis and risk stratification, but the measurement itself is automated.
7. The Type of Ground Truth Used
- Clinical Performance: Clinical diagnosis (presence or absence of congestive heart failure) was used as the ground truth for patients in the clinical study groups.
- Analytical Performance: The measurements from the predicate device (Roche Elecsys® proBNP immunoassay) served as the comparative analytical ground truth for method comparison studies. Known concentrations in control materials were used as ground truth for reproducibility.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of an AI/machine learning model, as this is an immunoassay, not an AI-driven image analysis or prediction model. The "training" in this context refers to the development and optimization of the assay itself and its calibration. The calibration process uses specific calibrator materials.
- Calibration: The assay uses a "pBNP Calibrator" which is a frozen liquid product containing synthetic human NT-proBNP. The kit consists of five CalPaks, each with three wells of calibrator reagent (a single calibrator level). The calibration curve is updated for each lot, using one level, and every 30 days thereafter.
9. How the Ground Truth for the Training Set was Established
For the immunoassay, the "ground truth" for calibration (analogous to training) is established by known concentrations of synthetic NT-proBNP in the calibrator materials. These calibrators are traceable to a reference standard (Roche purified synthetic NT-proBNP (1-76)). The specific concentrations of NT-proBNP in the calibrator solution are precisely manufactured and assigned to ensure accurate quantitative measurement by the assay.
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