(450 days)
HemosIL Liquid Anti-Xa is an automated chromogenic assay for in vitro diagnostic use by laboratory professionals in clinical laboratories. The assay provides quantitative results on 3.2% citrated human plasma for the following analytes based on the calibrators used:
. When used with HemosIL Heparin Calibrators:
Quantitative determination of unfractionated heparin (UFH) and low molecular weight heparin (LMWH) activity on the ACL TOP Family, ACL TOP Family 50 Series, and ACL Elite/Elite Pro.
· When used with HemosIL Apixaban Calibrators:
Quantitative determination of apixaban on the ACL TOP Family and ACL TOP Family 50 Series through measurement of Factor Xa activity, which is inversely proportional to the apixaban level. With HemosIL Apixaban Calibrators, the assay is intended to measure apixaban concentrations in patients on apixaban therapy in the following situations where measurement of apixaban levels could be useful to have as additional information:
- Patients at risk for major bleeding
- Patients experiencing a bleeding episode
The assay is not a stand-alone test and the results should be used in conjunction with other clinical and laboratory findings.
For use in adult population. For prescription use only.
HemosIL Liquid Heparin and HemosIL Liquid Anti-Xa are one stage chromogenic assays based on a synthetic chromogenic substrate and on Factor Xa inactivation. The assay provides quantitative apixaban results on 3.2% citrated human plasma when used with HemosIL Heparin Calibrators and/or HemosIL Apixaban Calibrators.
The assay contains:
- Factor Xa reagent purified bovine Factor Xa, Tris-Buffer, EDTA, dextran sulfate, . sodium chloride, and bovine serum albumin
- Chromogenic substrate liquid chromogenic substrate S-2732 and bulking agent .
The assay requires the following components which are not included in the assay kit:
- HemosIL Apixaban Calibrators two levels ( and ( ( ng/mL) of lyophilized calibrators . prepared from human citrated plasma containing apixaban, buffers, and stabilizers.
- HemosIL Apixaban Controls two levels (1) and (1) of lyophilized controls . prepared from human citrated plasma containing apixaban, buffers, and stabilizers,
- HemosIL Heparin Calibrator three levels (0, 0.8 and 2.0 IU/mL) of lyophilized . calibrators prepared from human citrated plasma containing heparin, buffer and stablizers.
- HemosIL LMW Heparin Controls two levels (low and high) of lyophilized controls . prepared from human citrated plasma containing low molecular weight (LMW) heparin, buffers and stabilizers. Each lot of LMW Heparin Controls is traceable to the 3rd International WHO Standadrd 11/176 for LMW heparin.
- Hemos IL UF Heparin Controls two levels (low and high) of lyophilized controls . prepared from human citrated plasma containing unfractionated (UF) heparin, buffers and stabilizers. Each lot of UF Heparin Controls is traceable to the 6th International WHO standard 07/328 for UF heparin.
- Cleaning solution .
- Cleaning agent .
- Factor diluent .
The HemosIL Liquid Anti-Xa assay is an automated chromogenic assay designed for in vitro diagnostic use to quantitatively determine unfractionated heparin (UFH), low molecular weight heparin (LMWH) activity, and apixaban levels in citrated human plasma.
Here's an analysis of its acceptance criteria and the study that proves its performance:
1. Table of Acceptance Criteria and Reported Device Performance
The document primarily focuses on analytical performance for apixaban, as heparin performance was previously reported. The key performance criteria evaluated for apixaban are precision, linearity/reportable range, traceability, stability, detection limits, and analytical specificity.
| Acceptance Criteria Category | Specific Acceptance Criteria (Implied/Direct from text) | Reported Device Performance (Apixaban) |
|---|---|---|
| Precision/Reproducibility | Within-run, between-run, between-day, between-instrument, between-lot, between-laboratory CV% should be acceptable for clinical use. | Study 4 (Multisite Precision): |
| Control 1 (71.0 ng/mL): Total CV 4.7% | ||
| Control 2 (290.0 ng/mL): Total CV 2.4% | ||
| Spiked 1 (53.9 ng/mL): Total CV 7.5% | ||
| Spiked 2 (721.6 ng/mL): Total CV 6.1% | ||
| Spiked 3 (954.5 ng/mL): Total CV 4.9% | ||
| Native (199.9 ng/mL): Total CV 5.9% | ||
| Study 5 (Multisite Diluted/Native Samples): | ||
| Diluted Native (59.7 ng/mL): Total CV 5.2% | ||
| Native 1 (106.1 ng/mL): Total CV 3.7% | ||
| Native 2 (246.9 ng/mL): Total CV 3.5% | ||
| All values indicate good precision. | ||
| Linearity/Reportable Range | Assay should be linear over the claimed reportable range. | Claimed reportable range: 20-1000 ng/mL; established through linearity studies with two separate linear regressions over different concentration ranges. |
| Traceability | Calibrators and controls should be traceable to a recognized standard. | Traceable to apixaban supplied by the manufacturer and quantitated in plasma by Liquid Chromatography - tandem Mass Spectrometry (LC-MS/MS). |
| Freeze-thaw Stability | Reagents should maintain stability over a specified number of freeze-thaw cycles. | Demonstrated stability for up to two freeze-thaw cycles. |
| Sample Stability | Citrated plasma samples should maintain stability under specified storage conditions. | Stable for 24 hours at 15-25°C and 7 days at 2-8°C. |
| Detection Limits (LoB, LoD, LoQ) | Should meet pre-defined limits for blank, detection, and quantitation. | LoB: (b)(4) (specific number redacted) |
| LoD: (b)(4) (specific number redacted) | ||
| LoQ: (b)(4) (specific number redacted) | ||
| Analytical Specificity/Interference | No clinically significant interference from common endogenous or exogenous substances. | None of the tested endogenous (Hemoglobin, Bilirubin, Triglycerides, Lupus anticoagulant) or exogenous (Acetylsalicylic acid, Atorvastatin, Isosorbide dinitrate, Ticagrelor, Warfarin) substances were found to cause clinically significant interference. |
| Clinical Accuracy (Method Comparison) | High correlation and acceptable agreement with a reference method. | N=367 clinical samples correlated with a validated apixaban LC-MS/MS method. |
| Linear Regression: r = 0.995; Slope = 1.101 (95% CI: (b)(4), (b)(4)); Intercept = -2.458 (95% CI: (b)(4), (b)(4)) | ||
| Relative Predicted Bias: Generally low and within acceptable clinical ranges across different apixaban concentrations (e.g., (b)(4) at 30 ng/mL, etc.). |
2. Sample Size Used for the Test Set and Data Provenance
- Precision Studies (Test Set):
- Study 1: 240 determinations (80 per reagent lot).
- Study 2: Total number of determinations not fully specified, but involved multiple instrument models and reagent lots.
- Study 3: No specific number of determinations given, states "prodeterminations".
- Study 4: 270 determinations (multisite).
- Study 5: 270 determinations (multisite).
- Linearity Studies (Test Set): Normal pooled plasma (NPP) spiked with known concentrations of apixaban, tested in four replicates.
- Detection Limit Studies (Test Set):
- LoB: n=60 determinations per reagent lot per instrument model (using four citrated plasma pools).
- LoD: n=60 determinations per reagent lot per instrument model (using four citrated plasma pools).
- LoQ: n=40 determinations per reagent lot per instrument model (using four citrated plasma pools).
- Analytical Specificity/Interference Studies (Test Set): Test samples (spiked with apixaban) and control samples, tested in a minimum of four replicates.
- Clinical Accuracy (Method Comparison Study Test Set): 367 clinical samples collected from patients receiving apixaban.
- Data Provenance: The method comparison study involved clinical samples collected from three different U.S. clinical sites. This indicates the data is prospective or retrospective clinical data, collected in a real-world setting.
- For the analytical studies (precision, linearity, detection limits, interference), these were laboratory-controlled studies using spiked or pooled plasma samples.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
For the clinical accuracy study, the ground truth was established by a validated apixaban LC-MS/MS method. The document does not specify the number or qualifications of experts involved in running or validating this LC-MS/MS method, as LC-MS/MS is a highly sensitive and precise analytical technique typically performed by trained laboratory personnel.
4. Adjudication Method for the Test Set
Not applicable. The ground truth for the clinical accuracy study was established by a quantitative instrumental method (LC-MS/MS), not through expert consensus requiring adjudication.
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 automated in vitro diagnostic assay, not an imaging or diagnostic interpretation device that would typically involve human readers. Therefore, the concept of human readers improving with AI vs. without AI assistance does not apply.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) Was Done
Yes, the studies reported are standalone performance evaluations of the HemosIL Liquid Anti-Xa assay (an automated algorithm/instrument system). The performance characteristics presented are for the device itself, generating quantitative results. While the device results are intended to be used by laboratory professionals and clinicians, the performance of the device is measured directly, not in conjunction with human interpretation for accuracy.
7. The Type of Ground Truth Used
- Analytical Performance Studies (Precision, Linearity, Detection Limits): Ground truth was established by known concentrations of apixaban used to spike samples, or intrinsic properties of control materials and pooled plasma.
- Clinical Accuracy (Method Comparison Study): Ground truth was established by a validated apixaban Liquid Chromatography - tandem Mass Spectrometry (LC-MS/MS) method. LC-MS/MS is considered a gold standard for drug quantification.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of machine learning. The HemosIL Liquid Anti-Xa is a chromogenic assay based on biochemical reactions and factor Xa inactivation, not a machine learning algorithm that requires specific training data in the traditional sense. The development of such assays involves extensive R&D, reagent optimization, and calibration curve generation, which could be seen as analogous to "training" but is not reported with a distinct sample size for "training set" in this context.
9. How the Ground Truth for the Training Set Was Established
As noted above, a traditional "training set" as understood in machine learning is not applicable here. The assay relies on established biochemical principles and calibration against known standards.
- Calibration: For apixaban, calibrator value assignments are traceable to apixaban supplied by the manufacturer and quantitated in plasma assayed by LC-MS/MS. This process ensures the assay accurately measures apixaban concentrations.
§ 864.7295 Heparin and direct oral factor Xa inhibitor drug test system.
(a)
Identification. A heparin and direct oral factor Xa inhibitor drug test system is intended for the detection of heparin and direct oral factor Xa inhibitors in human specimens collected from patients taking heparin or direct oral factor Xa inhibitors. This device is intended to aid in the management of therapy in conjunction with other clinical and laboratory findings.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Design verification and validation must include the following:
(i) Detailed documentation of analytical device performance studies and results demonstrating acceptable analytical performance with a sufficient number of specimens tested in order to obtain unbiased estimates of analytical performance. This documentation shall include the following as appropriate to the technology, specimen types tested, and intended use of the device:
(A) Studies and results for that demonstrate device precision including repeatability and reproducibility, using quality controls and clinical samples, when appropriate. Precision studies must assess specimens for each indicated drug at concentrations throughout the measuring range of the device including near clinically relevant levels, as appropriate. The study must evaluate different sources of variability including, as appropriate, between-run, between-operator, between-lot, between-instrument, between-day, and between-site;
(B) Studies and results that demonstrate that the device is free from clinically significant interference, from endogenous and exogenous interferents associated with the target population(s), and interferents that are specific for, or related to, the technology or methodology of the device;
(C) Data to demonstrate appropriate specimen stability for the intended sample matrices under the intended conditions for specimen collection, handling, and storage described in the device labeling;
(D) Studies and results that demonstrate the linear range, limit of blank (LoB), limit of detection (LoD), and limit of quantitation (LoQ), as applicable to the technology of the device; and
(E) For any devices intended for use for near patient testing, studies and results that demonstrate the robustness of the device in the hands of the intended user, including the entire testing procedure, pre-analytical specimen processing steps, and results interpretation.
(ii) Detailed documentation of clinical performance testing in which the performance is analyzed relative to a comparator that FDA has determined is appropriate. Specimens must be representative of the intended use population(s) and must cover the full range of the device output and any clinically relevant decision points as appropriate.
(2) The labeling required under § 809.10(b) of this chapter must include:
(i) Identification of any known interferents, including all endogenous, exogenous, technology-specific, and patient population-specific interferents, specific to the test outputs. The information must include the concentration(s) or level(s) of the interferent at which clinically significant interference was found to occur, and the concentration range or levels at which interference was not found to occur;
(ii) A prominent statement that the device is not intended for use in monitoring patients taking heparin or direct oral factor Xa inhibitors; and
(iii) Limiting statements indicating, as applicable:
(A) That the device should only be used in conjunction with information available from clinical evaluations and other diagnostic procedures; and
(B) That the device is not specific to the direct oral factor Xa inhibitor that has been evaluated and may detect the presence of other direct factor Xa inhibitors that have not been evaluated.