(427 days)
The Invader® MTHFR 1298 test is an in vitro diagnostic test intended for the detection and genotyping of a single point mutation (A to C at position 1298) of the human 5,10-methylenetetrahydrofolate reductase (MTHFR) gene in isolated genomic DNA obtained from whole blood potassium EDTA samples from patients with suspected thrombophilia.
The Invader MTHFR 1298 test consists of the following components:
MTHFR 1298 Oligo Mix
Universal Buffer
Universal Enzyme Mix
No DNA Control
MTHFR 1298 Wild Type Control
MTHFR 1298 Heterozygous Control
MTHFR 1298 Mutant Control
Invader Call Reporter™ Software
Invader® MTHFR 1298 Software
Here's an analysis of the Invader® MTHFR 1298 device based on the provided text, addressing your specific questions.
1. Table of Acceptance Criteria and Reported Device Performance
(Note: The document does not explicitly state "acceptance criteria" in a separate section with pass/fail thresholds for each study. Instead, it presents study results and concludes that the information "supports a substantial equivalence decision." The table below infers the implicit acceptance criterion as 100% agreement/concordance where achieved, and notes the precise percentage reported for other metrics.)
| Performance Characteristic | Acceptance Criteria (Inferred) | Reported Device Performance |
|---|---|---|
| Reproducibility (Inter-laboratory) | 100% Correct Calls, 0% No Calls, 0% Miscalls | 100% Final Agreement (540/540 samples across 3 sites, 2 operators each) |
| Reproducibility (Lot-to-Lot) | 100% Agreement with sequencing | 100% Agreement with sequencing (108/108 samples across 3 lots) |
| Real-time Stability | 100% Agreement with sequencing/expected genotype | 100% Agreement (all controls and gDNA samples across 3 lots and 3 timepoints up to 7 months) |
| Freeze-Thaw Stability | 100% Agreement with sequencing | 100% Agreement (all controls and gDNA samples through 15 freeze-thaw cycles) |
| Analytical Sensitivity (Concentration Range) | 100% Concordance with bi-directional sequencing | 100% Concordance for gDNA concentrations between 5-80 ng/µL (3 samples, 240 replicates) |
| Analytical Specificity (Interfering Substances) | 100% Agreement with sequencing and untreated samples | 100% Agreement (all tested interfering substances) |
| Pre-Analytical Equivalency (Extraction Reproducibility) | 100% Agreement with bi-directional sequencing | 100% Agreement (159/160 samples, 4 extraction methods) |
| Instrument Equivalency (Thermal Cycler & Fluorometer) | 100% Concordance with bi-directional sequencing | 100% Concordance (all combinations of 3 thermal cyclers and 3 fluorometers) |
| Method Comparison (Bi-directional Sequencing) | High agreement with bi-directional sequencing (explicit criteria not specified, but 100% is typical for substantial equivalence) | 99.71% First Run Agreement (347/348 samples); 100% (347/347) for valid results |
2. Sample Size Used for the Test Set and Data Provenance
- Inter-laboratory Reproducibility (Study #1):
- Test Set Sample Size: 9 (panel of genomic DNA samples representing 3 genotypes: wild type, heterozygous, homozygous mutant).
- Total Tests Performed: 540 (9 samples x 2 operators/site x 3 sites x 2 duplicates/day x 5 days of testing).
- Data Provenance: Not specified, but involved 2 external sites and 1 internal site. The samples were "whole blood samples specific for each of the three possible genotypes." Implied retrospective as specific genotypes were selected.
- Lot-to-Lot Reproducibility (Study #9):
- Test Set Sample Size: 9 (genomic DNA samples: 3 wild type, 3 heterozygous, 3 mutants).
- Total Tests Performed: 108 (9 samples x 4 replicates x 3 lots).
- Data Provenance: Not specified, but samples were "genomic DNA samples." Implied retrospective.
- Real-time Stability (Study #5):
- Test Set Sample Size: 3 genomic DNA samples (WT, HET, MUT) + 3 controls.
- Total Tests Performed: Performed in quadruplicate at each time point (initial, 4 months, 7 months) for 3 lots. Total: (3 gDNA + 3 controls) x 4 replicates x 3 lots x 3 time points = 216 tests.
- Data Provenance: Not specified.
- Freeze-Thaw Stability (Study #6):
- Test Set Sample Size: 3 genomic DNA samples (WT, HET, MUT) + 3 controls.
- Total Tests Performed: The table indicates varying numbers of tests per sample per freeze/thaw cycle. Total for gDNA: 36 (WT), 48 (HET), 36 (MUT). Total for controls: 45 each. Total overall is 255.
- Data Provenance: Genomic DNA isolated from cell lines.
- Analytical Sensitivity (Detection Limit) (Study #3):
- Test Set Sample Size: 3 genomic DNA samples (1 MUT, 1 HET, 1 WT).
- Total Tests Performed: 960 (3 samples x 8 concentrations x 40 replicates).
- Data Provenance: "Genomic DNA samples with different genotypes (i.e. WT, HET, MUT) were extracted from whole blood collected in potassium EDTA." Implied retrospective.
- Analytical Specificity (Interfering Substances) (Study #4):
- Test Set Sample Size: 9 whole blood samples (3 WT, 3 HET, 3 MUT).
- Total Tests Performed: 18 tests per substance (9 samples x 2 replicates). 7 substances + 1 control = 8 conditions. Total: 18 x 8 = 144 tests.
- Data Provenance: "human whole blood samples." Implied retrospective.
- Pre-Analytical Equivalency (Genomic DNA Extraction Reproducibility) (Study #7):
- Test Set Sample Size: 30 human whole blood samples + 10 leukocyte depleted whole blood spiked with cell lines = 40 unique samples.
- Total Tests Performed: 160 (40 samples x 4 extraction methods, analyzed in singlicate).
- Data Provenance: "human whole blood samples and leukocyte depleted whole blood spiked with cell lines." Implied retrospective.
- Instrument Equivalency (Study #8):
- Test Set Sample Size: 29 human whole blood samples + 10 leukocyte depleted whole blood samples = 39 unique samples.
- Total Tests Performed: 78 tests were reported per combination of fluorometer/thermal cycler. Overall: 39 samples x 2 extraction methods x 3 thermal cyclers x 3 fluorometers (but results are combined for each fluorometer/cycler pairing). The table shows 78 total tests for each of the 9 combinations.
- Data Provenance: "human whole blood samples and leukocyte depleted whole blood samples spiked with cell lines." Implied retrospective.
- Method Comparison (Bi-directional Sequencing) (Study #2):
- Test Set Sample Size: 348 human whole blood samples.
- Data Provenance: "Human whole blood samples (n = 348)." Implied retrospective.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document does not explicitly state the number or qualifications of experts used to establish ground truth.
For ground truth established by bi-directional sequencing, it's a laboratory method that typically involves trained molecular biologists or laboratory technicians. The results are considered highly accurate.
4. Adjudication Method for the Test Set
The document does not describe an adjudication method for the test sets. The ground truth was primarily established by bi-directional sequencing, which is considered a definitive method, minimizing the need for adjudication in the traditional sense (e.g., of discrepant expert reads).
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
This section is not applicable. The Invader® MTHFR 1298 is an in vitro diagnostic molecular test for genotyping a specific gene mutation. It is not an imaging or interpretive AI device that involves human "readers" or assesses "AI assistance." The device outputs a direct genotype call (WT, HET, MUT).
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the device's performance studies were conducted in a standalone manner. The Invader® MTHFR 1298 test is an automated system where the Invader Call Reporter™ Software processes raw fluorescence data to determine genotypes. Human input is in sample preparation and loading, and reviewing the generated report, but the genotyping call itself is algorithm-driven without real-time human interpretation embedded in the performance measurement. The various studies (reproducibility, sensitivity, specificity, method comparison) directly evaluate this standalone algorithmic performance against a known ground truth (sequencing).
7. The Type of Ground Truth Used
The primary ground truth used for all performance studies was bi-directional DNA sequencing. This is considered the gold standard for confirming specific genetic variations. For some studies, expected genotypes based on controls or known cell lines were also used, which would have initially been characterized by sequencing.
8. The Sample Size for the Training Set
The document primarily describes validation studies and does not explicitly mention a "training set" in the context of device development. For IVD devices, a training set generally refers to the data used to initially develop and optimize the assay parameters and interpretation algorithms. Such details are typically proprietary and not extensively disclosed in 510(k) summaries, which focus on performance validation. The studies described are validation and verification studies using independent "test sets."
9. How the Ground Truth for the Training Set Was Established
As no specific "training set" details are provided, the method for establishing its ground truth is also not described. However, it can be inferred that any samples used for initial assay development and algorithm optimization would also have had their MTHFR 1298 genotype established using a highly accurate method, most likely bi-directional DNA sequencing, similar to the validation studies.
§ 864.7280 Factor V Leiden DNA mutation detection systems.
(a)
Identification. Factor V Leiden deoxyribonucleic acid (DNA) mutation detection systems are devices that consist of different reagents and instruments which include polymerase chain reaction (PCR) primers, hybridization matrices, thermal cyclers, imagers, and software packages. The detection of the Factor V Leiden mutation aids in the diagnosis of patients with suspected thrombophilia.(b)
Classification. Class II (special controls). The special control is FDA's guidance entitled “Class II Special Controls Guidance Document: Factor V Leiden DNA Mutation Detection Systems.” (See § 864.1(d) for the availability of this guidance document.)