(252 days)
HemosIL HIT-Ab(PF4-H) is a qualitative, fully automated, latex enhanced immunoassay for the detection of anti-platelet factor 4/heparin (PF4/H) antibodies. The assay is for use in human 3.2% or 3.8% citrated plasma on the ACL TOP® Family of instruments in a laboratory setting.
The result provided by the assay should be interpreted as either positive based on the assay cut-off (1.0 U/ mL). The positive or negative result aids in determining the risk for heparin induced thrombocytopenia (HIT) when used in conjunction with other laboratory and clinical findings.
Anti-PF4/Heparin antibodies are commonly found in patients with HIT. For use in adult population suspected of HIT. Not for use in isolation to exclude HIT.
HemosIL HIT-Ab(PF4-H) Controls are for the Quality Control of the HemosIL HIT-Ab(PF4-H) assay as performed on the ACL TOP® Family of instruments.
For prescription use.
The HemosIL HIT-Ab(PF4-H) kit is a latex particle enhanced immuno-turbidimetric assay to detect total Anti-PF4/Heparin (PF4/H) antibodies found in HIT patients. A monoclonal antibody that mimics human HIT antibodies is coated onto latex particles.
In the presence of PF4 from human platelets complexed to polyvinyl sulfonate (PVS), and the patient sample, a competitive agglutination reaction occurs.
The degree of agglutination is inversely proportional to the concentration of antibodies in the sample and is determined by measuring the decrease of transmitted light caused by the aggregates.
The HemosIL HIT- Ab(PF4-H) kit consists of:
Latex Reagent: Suspension of polystyrene latex particles coated with purified mouse monoclonal anti-PF4-Heparin in Tris buffer, containing bovine serum albumin, stabilizers and preservative.
Stabilizer: PBS buffer containing bovine serum albumin, stabilizers and preservative.
Complex: Solution of PF4-PVS complex (PF4 from human platelets complexed to PVS), in PBS buffer containing bovine serum albumin, stabilizers and preservative. Contains 0.02% Bronidox™ as a preservative.
Calibrator: Lyophilized solution of a monoclonal anti- PF4-Heparin antibody in Tris buffer containing bovine serum albumin, stabilizers and preservative.
The Low and High HIT-Ab(PF4-H) Controls are prepared by means of a dedicated process and contain different concentrations of humanized monoclonal anti-PF4-Heparin-human IgG.
Low HIT-Ab(PF4-H) Control: Control intended for the assessment of precision and accuracy of the assay at PF4/H antibody levels at or below the cut-off.
High HIT-Ab(PF4-H) Control: Control intended for the assessment of precision and accuracy of the assay at abnormal PF4/H antibody levels.
Use of both controls is recommended for a complete quality control program.
Here's a breakdown of the acceptance criteria and the studies performed for the HemosIL HIT-Ab(PF4-H) device, based on the provided FDA 510(k) summary:
1. Table of Acceptance Criteria and Reported Device Performance
The document does not explicitly state "acceptance criteria" in a singular section with numerical targets for clinical performance. Instead, it presents various performance metrics derived from different studies. The conclusion states that the device is "substantially equivalent" to the predicate and "safe and effective."
Given this, I will infer "acceptance criteria" from the comparative studies presented and consider the reported performance to be the "device performance."
| Category | Specific Metric | Implied Acceptance Criteria (Inferred) | Reported Device Performance | Study |
|---|---|---|---|---|
| Precision | %CV for Low HIT-Ab(PF4-H) Control (Total) | (Not explicitly stated, but generally below 10-15% for controls is considered good for immunoassay) | Reagent Lot 1: 9.9% Reagent Lot 2: 9.3% Reagent Lot 3: 9.9% Low Control Lot 1: 9.9% Low Control Lot 2: 9.2% Low Control Lot 3: 8.9% | Multi-Reagent Lot Precision, Multi-Control Lot Precision |
| %CV for High HIT-Ab(PF4-H) Control (Total) | (Not explicitly stated, but generally below 10-15% for controls is considered good for immunoassay) | Reagent Lot 1: 3.3% Reagent Lot 2: 3.9% Reagent Lot 3: 4.0% High Control Lot 1: 3.3% High Control Lot 2: 3.0% High Control Lot 3: 2.6% | Multi-Reagent Lot Precision, Multi-Control Lot Precision | |
| %CV for Patient Samples (Total) | (Not explicitly stated, but generally below 10-15% for clinical samples is considered good) | Ranging from 3.8% to 13.5% across various plasma samples and reagent lots | Multi-Reagent Lot Precision, Unadulterated Patient Plasma Precision | |
| Reproducibility (Total %CV) | Low HIT-Ab(PF4-H) Control | (Not explicitly stated, but generally acceptable for multi-site) | Reagent Lot 1: 15.3% Reagent Lot 2: 7.4% Reagent Lot 3: 11.0% Pooled 3-Site Data (Control Lot): 15.3% | Multi-Reagent Lot Site-to-Site Reproducibility, Multi-Control Lot Reproducibility |
| High HIT-Ab(PF4-H) Control | (Not explicitly stated, but generally acceptable for multi-site) | Reagent Lot 1: 6.1% Reagent Lot 2: 5.2% Reagent Lot 3: 5.5% Pooled 3-Site Data (Control Lot): 6.1% | Multi-Reagent Lot Site-to-Site Reproducibility, Multi-Control Lot Reproducibility | |
| Instrument Equivalency | Correlation Coefficient (r) between ACL TOP 700 and 500 CTS | (Typically > 0.95 for good correlation) | 0.9947 | Instrument Model Equivalency |
| Correlation Coefficient (r) between ACL TOP 700 and 300 CTS | (Typically > 0.95 for good correlation) | 0.9981 | Instrument Model Equivalency | |
| Linearity Range | Auto Rerun off | Performance to support claims | 0.6 – 5.7 U/mL | Linearity and Test Ranges |
| Auto Rerun on | Performance to support claims | 2.1 – 16.0 U/mL | Linearity and Test Ranges | |
| Method Comparison vs. Predicate (Internal) | PPA | (Generally aims for high agreement, e.g., >80%) | 84% (68/81) | Method Comparison (Internal) |
| NPA | (Generally aims for high agreement, e.g., >70-80%) | 78% (29/37) | Method Comparison (Internal) | |
| Total Percent Agreement | (Generally aims for high agreement, e.g., >80%) | 82% (97/118) | Method Comparison (Internal) | |
| Method Comparison vs. Predicate (Multicenter) | PPA | (Generally aims for high agreement, e.g., >70-80%) | 75% (67/89) | Multicenter Method Comparison |
| NPA | (Generally aims for high agreement, e.g., >90%) | 93% (504/543) | Multicenter Method Comparison | |
| Total Percent Agreement | (Generally aims for high agreement, e.g., >80%) | 90% (571/632) | Multicenter Method Comparison | |
| Method Comparison vs. SRA (HemosIL HIT-Ab(PF4-H)) | PPV | (Aids in determining risk, specific threshold not given as primary criterion) | 37% (33/89) | Multicenter Method Comparison |
| NPV | (Aims for high negative predictive power) | 87% (389/448) | Multicenter Method Comparison | |
| Method Comparison vs. SRA (Predicate - Asserachrom HPIA) | PPV | (For comparison to newly developed device) | 46% (31/68) | Multicenter Method Comparison |
| NPV | (For comparison to newly developed device) | 87% (408/469) | Multicenter Method Comparison | |
| Method Comparison vs. ASH 2013 Guidelines | PPA | (Aims for high agreement with clinical guidelines) | 89% (17/19) | HemosIL HIT-Ab(PF4-H) Assay vs. 2013 American Society of Hematology (ASH) Guidelines |
| NPA | (Aims for high agreement with clinical guidelines) | 86% (446/518) | HemosIL HIT-Ab(PF4-H) Assay vs. 2013 American Society of Hematology (ASH) Guidelines | |
| NPV | (Aims for high negative predictive value with clinical guidelines) | 100% (446/448) | HemosIL HIT-Ab(PF4-H) Assay vs. 2013 American Society of Hematology (ASH) Guidelines |
2. Sample Sizes Used for Test Sets and Data Provenance
-
Multi-Reagent Lot Precision:
- Sample Size: 2 controls (low and high) and 5 patient plasma pools. Each tested in duplicate, twice a day for 20 days (80 replicates per level per lot). Total of 7 levels * 80 replicates = 560 data points per reagent lot. With 3 reagent lots, this is 1680 data points for the precision study itself.
- Data Provenance: Not explicitly stated for patient pools, but controls are internal. Patient plasma samples 1-5's origin is not specified but are described as "prepared at different levels to span the assay range", implying they are manufactured or manipulated samples.
- Nature: Prospective (testing conducted for the study).
-
Multi-Reagent Lot Site-to-Site Reproducibility:
- Sample Size: 2 controls (low and high), 3 patient pools, and 1 manufactured material (Plasma Sample 4). Each tested in triplicate, twice a day for 5 days (30 replicates per level). Total of 6 levels * 30 replicates = 180 data points per site per reagent lot. With 3 sites and 3 reagent lots, this is 180 * 3 * 3 = 1620 data points.
- Data Provenance: Not explicitly stated for patient pools or manufactured material, but they are "patient pools (2 positive)" and "a manufactured material containing a citrated plasma sample spiked with monoclonal anti-PF4-Heparin antibody."
- Nature: Prospective (testing conducted for the study).
-
Multi-Control Lot Precision:
- Sample Size: 2 control levels (low and high) from 3 different control lots. Each tested in duplicate, twice a day for 20 days (80 replicates per level per lot). Total of 6 levels * 80 replicates = 480 data points.
- Data Provenance: Controls are manufactured by Instrumentation Laboratory (IL).
- Nature: Prospective (testing conducted for the study).
-
Multi-Control Lot Reproducibility:
- Sample Size: 2 control levels (low and high). Each tested in triplicate, twice a day for 5 days (30 replicates per level). Total of 2 levels * 30 replicates = 60 data points per site. With 3 sites, 180 data points.
- Data Provenance: Controls are manufactured by Instrumentation Laboratory (IL).
- Nature: Prospective (testing conducted for the study).
-
Multi-Calibrator Lot Precision:
- Sample Size: 3 different calibrator lots. Each tested in duplicate, twice a day for 20 days (80 replicates per lot). Total of 3 lots * 80 replicates = 240 data points.
- Data Provenance: Calibrators are kit components from the manufacturer.
- Nature: Prospective (testing conducted for the study).
-
Unadulterated Patient Plasma Precision:
- Sample Size: 2 patient plasma samples. Each tested in duplicate, twice a day for 10 days (40 replicates per sample). Total of 2 samples * 40 replicates = 80 data points.
- Data Provenance: Collected at a hospital in the United States.
- Nature: Retrospective (though tested prospectively for precision study, samples were previously collected).
-
Instrument Model Equivalency:
- Sample Size: 51 citrated plasma samples.
- Data Provenance: Individual clinical patients suspected of HIT.
- Nature: Retrospective (samples previously collected, tested on multiple instruments).
-
Linearity and Test Ranges:
- Sample Size: Not explicitly stated as a number of patient samples, but 10 concentrations across 0.6-5.7 U/mL and a third extremely high positive sample for 2.1-16.0 U/mL. Two positive patient samples were used to prepare serial dilutions.
- Data Provenance: Patient samples spiked into donor plasma from a blood bank.
- Nature: Prospective (dilution series prepared and tested).
-
Heparin Sensitivity:
- Sample Size: 126 citrated plasma samples.
- Data Provenance: Non-HIT suspected, heparin treated patients (UFH or LMWH).
- Nature: Retrospective (samples previously collected).
-
Antiphospholipid Syndrome (APS):
- Sample Size: 40 citrated plasma samples.
- Data Provenance: Patients diagnosed with Antiphospholipid Syndrome (APS).
- Nature: Retrospective (samples previously collected).
-
Reference Interval – Healthy Donors:
- Sample Size: 131 citrated plasma samples.
- Data Provenance: Apparently healthy individuals.
- Nature: Retrospective (samples previously collected).
-
Reference Interval – Heparin Exposed, HIT Suspected Patients (HIT Negative):
- Sample Size: 122 citrated plasma samples.
- Data Provenance: HIT-suspected, but negative by a commercially available ELISA.
- Nature: Retrospective (samples previously collected).
-
Cut-Off Determination:
- Sample Size: 63 citrated plasma samples (31 SRA positive, 32 SRA negative).
- Data Provenance: Hospitalized patients exposed to heparin with clinical signs of HIT.
- Nature: Retrospective (samples previously collected and tested by SRA).
-
Method Comparison (Internal):
- Sample Size: 118 frozen citrated patient plasma samples.
- Data Provenance: Patients referred for HIT testing from a hospital in the US and a hospital in France.
- Nature: Retrospective (samples previously collected, tested against predicate).
-
Multicenter Method Comparison (against predicate and SRA):
- Sample Size: 632 patient samples initially (N=537 for SRA comparison after removing invalid/indeterminate SRA results).
- Data Provenance: From patients exposed to heparin who showed HIT related symptoms, collected at three (3) hospitals.
- Nature: Multicenter, Retrospective (samples previously collected, tested against predicate and SRA).
-
HemosIL HIT-Ab(PF4-H) Assay vs. 2013 American Society of Hematology (ASH) Guidelines:
- Sample Size: 537 patient samples (subset of the multicenter study).
- Data Provenance: From patients exposed to heparin who showed HIT related symptoms, collected at three (3) hospitals.
- Nature: Retrospective (analysis of previously collected data against clinical guidelines).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- For studies comparing to a predicate device (Asserachrom HPIA Test Kit), the predicate itself served as the comparator, and its established performance and cut-offs formed the "ground truth" for comparison. The predicate device's ground truth would have been established during its own clearance.
- For studies comparing to the Serotonin Release Assay (SRA), the SRA results were considered the "reference device" and "ground truth." The SRA is a functional assay for HIT antibodies and is often considered the gold standard, although the document doesn't specify how the SRA results themselves were "ground-truthed" (e.g., if multiple SRA runs were done, or expert interpretation). No specific number of experts or their qualifications for interpreting SRA results is mentioned.
- For the Cut-Off Determination study, SRA results (31 SRA positive and 32 SRA negative) from hospitalized patients were used as the ground truth. Again, no specific information on experts for SRA.
- For the ASH Guidelines comparison, the 2013 ASH diagnostic algorithm, which incorporates clinical probability (4T score), ELISA results, and SRA results, served as the "ground truth" or reference framework. This is a clinical guideline, not directly "expert-established ground truth" for individual cases in this context, but rather an established diagnostic framework.
- For other analytical studies (precision, reproducibility, linearity, etc.), the ground truth is based on the inherent properties of the samples and controls used, not dependent on expert interpretation.
4. Adjudication Method for the Test Set
- The document does not specify an adjudication method for establishing ground truth for the clinical samples. For studies comparing to the SRA or the predicate, it appears the results of these reference methods were taken directly without a separate adjudication process by additional experts.
- For the ASH guideline comparison, the algorithm itself incorporates different types of evidence.
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
- No, an MRMC comparative effectiveness study was not done.
- This device, HemosIL HIT-Ab(PF4-H), is an in-vitro diagnostic (IVD) immunoassay, which performs automated detection of antibodies. It is not an AI-assisted diagnostic imaging or interpretation device that would involve human "readers" or benefit from "AI assistance" in the way described for an MRMC study. Its output is a quantitative (U/mL) and qualitative (positive/negative) result based on an assay cut-off.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Yes, the primary performance studies are standalone algorithm-only performance. The HemosIL HIT-Ab(PF4-H) assay is a "fully automated, latex enhanced immunoassay" performed on the ACL TOP Family of instruments. The results generated by the instrument are quantitative (U/mL) and then interpreted as positive or negative based on a fixed cut-off (1.0 U/mL). All the precision, reproducibility, linearity, and method comparison studies described are evaluating the performance of this automated assay directly, without human interpretation of raw data beyond the standard laboratory operation of running the assay and reporting the final result.
7. The Type of Ground Truth Used
- Predicate Device Performance: The primary ground truth for demonstrating substantial equivalence was the performance of the Asserachrom HPIA Test Kit, a legally marketed predicate ELISA device.
- Serotonin Release Assay (SRA): For clinical validity, the SRA, a functional assay for HIT antibodies, was used as a reference device and
considered the functional ground truth. - Clinical Guidelines: The 2013 American Society of Hematology (ASH) guidelines (incorporating 4T score, ELISA, and SRA) were used as a comprehensive clinical framework for comparison.
- Internal Controls and Materials: For analytical performance studies (precision, linearity), the ground truth was established by the known concentrations/compositions of manufacturer-prepared controls, calibrators, and spiked plasma pools.
8. The Sample Size for the Training Set
- The document does not explicitly delineate separate "training" and "test" sets in the context of machine learning or AI development, as this is an IVD immunoassay.
- Instead, development and optimization of the assay (analogous to training in ML) would involve internal R&D studies. The summary primarily focuses on the validation studies (analogous to testing).
- The "Cut-Off Determination" study describes using 63 samples (31 SRA positive, 32 SRA negative) and performing ROC analysis to determine the clinical cut-off of 1.0 U/mL. While this is not a "training set" in the AI sense, these samples were used to establish a critical parameter for the device's interpretation.
9. How the Ground Truth for the Training Set Was Established
- As noted above, there isn't a "training set" in the AI sense.
- For the "Cut-Off Determination" study, which used samples to establish the 1.0 U/mL cut-off:
- Ground Truth was established using Serotonin Release Assay (SRA) results. These SRA results classified the 63 samples as positive or negative for HIT antibodies.
- These samples were from "hospitalized patients who had been exposed to heparin, and who displayed clinical signs consistent with Heparin Induced Thrombocytopenia (HIT)," and were "tested by the hospital with the Serotonin Release Assay (SRA)." This implies the SRA results were clinical results from a standard reference method.
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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
July 08, 2016
Instrumentation Laboratory (IL) Co. Ms. Carol Marble Regulatory Affairs Director 180 Hartwell Road Bedford. MA 01730
Re: K153137
Trade/Device Name: HemosIL HIT-Ab(PF4-H); HemosIL HIT-Ab(PF4-H) Controls Regulation Number: 21 CFR 864.7695 Regulation Name: Platelet factor 4 radioimmunoassay Regulatory Class: Class II Product Code: LCO, GGN Dated: June 6, 2016 Received: June 8, 2016
Dear Ms. Marble:
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21
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CFR Part 807); labeling (21 CFR Parts 801 and 809); medical device reporting (reporting of medical device-related adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/Resourcesfor You/Industry/default.htm. Also, please note the regulation entitled. "Misbranding by reference to premarket notification" (21CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to
http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.
You may obtain other general information on your responsibilities under the Act from the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.
Sincerely yours.
Leonthena R. Carrington -S
Leonthena R. Carrington, MS, MBA, MT(ASCP) Director Division of Immunology and Hematology Devices Office of In Vitro Diagnostics and Radiological Health Center for Devices and Radiological Health
Enclosure
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Indications for Use
510(k) Number (if known) K153137
Device Name HemosIL HIT-Ab(PF4-H) HemosIL HIT- Ab(PF4-H) Controls
Indications for Use (Describe)
HemosIL HIT-Ab(PF4-H) is a qualitative, fully automated, latex enhanced immunoassay for the detection of anti-platelet factor 4/heparin (PF4/H) antibodies. The assay is for use in human 3.2% or 3.8% citrated plasma on the ACL TOP® Family of instruments in a laboratory setting.
The result provided by the assay should be interpreted as either positive based on the assay cut-off (1.0 U/ mL). The positive or negative result aids in determining the risk for heparin induced thrombocytopenia (HIT) when used in conjunction with other laboratory and clinical findings.
Anti-PF4/Heparin antibodies are commonly found in patients with HIT. For use in adult population suspected of HIT. Not for use in isolation to exclude HIT.
HemosIL HIT-Ab(PF4-H) Controls are for the Quality Control of the HemosIL HIT-Ab(PF4-H) assay as performed on the ACL TOP® Family of instruments.
For prescription use.
| Type of Use (Select one or both, as applicable) | |
|---|---|
| ☑ Prescription Use (Part 21 CFR 801 Subpart D) | □ Over-The-Counter Use (21 CFR 801 Subpart C) |
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510(k) Summary
This 510(k) Summary of Safety and Effectiveness is being submitted in accordance with the requirements of the Safe Medical Device Act of 1990 and 21 CFR 807.92.
| Submitter's Information | Instrumentation Laboratory (IL) Co. | ||
|---|---|---|---|
| 180 Hartwell Road | |||
| Bedford, MA 01730, USA | |||
| Contact Person | Carol Marble, Regulatory Affairs Director | ||
| Phone: 781-861-4467 | |||
| Fax: 781-861-4207 | |||
| Email: cmarble@ilww.com | |||
| Preparation Date | June 28, 2016 | ||
| Device Trade Names | Reagent Kit (with Calibrator) | HemosIL HIT-Ab(PF4-H) | |
| Controls | HemosIL HIT-Ab(PF4-H) Controls | ||
| Regulatory Information -Reagent Kit | Regulation Number | 21 CFR 864.7695 | |
| Regulation Description | Platelet Factor 4 Radioimmunoassay | ||
| Classification | Class II | ||
| Product Code | LCO | ||
| Classification Panel | Hematology (81) | ||
| Regulatory Information -Controls | Regulation Number | 21 CFR 864.5425 | |
| Regulation Description | Plasma, Coagulation Control | ||
| Classification | Class II | ||
| Product Code | GGN | ||
| Classification Panel | Hematology (81) | ||
| Predicate Device | K003767 (Asserachrom HPIA Test kit from Diagnostica Stago) |
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| Indications for Use /Intended Use | HemosIL HIT-Ab(PF4-H) is a qualitative, fully automated, latex enhancedimmunoassay for the detection of anti-platelet factor 4/heparin (PF4/H)antibodies. The assay is for use in human 3.2% or 3.8% citrated plasma onthe ACL TOP® Family of instruments in a laboratory setting.The result provided by the assay should be interpreted as either positive ornegative based on the assay cut-off (1.0 U/mL). The positive or negativeresult aids in determining the risk for heparin induced thrombocytopenia(HIT) when used in conjunction with other laboratory and clinical findings.Anti-PF4/Heparin antibodies are commonly found in patients with HIT. Foruse in adult population suspected of HIT. Not for use in isolation toexclude HIT.HemosIL HIT-Ab(PF4-H) Controls are for the Quality Control of the HemosILHIT-Ab(PF4-H) assay as performed on the ACL TOP Family of instruments.For prescription use. |
|---|---|
| Device DescriptionReagent Kit withCalibrator | The HemosIL HIT-Ab(PF4-H) kit is a latex particle enhanced immuno-turbidimetric assay to detect total Anti-PF4/Heparin (PF4/H) antibodiesfound in HIT patients. A monoclonal antibody that mimics human HITantibodies is coated onto latex particles.In the presence of PF4 from human platelets complexed to polyvinylsulfonate (PVS), and the patient sample, a competitive agglutinationreaction occurs.The degree of agglutination is inversely proportional to the concentrationof antibodies in the sample and is determined by measuring the decreaseof transmitted light caused by the aggregates.The HemosIL HIT- Ab(PF4-H) kit consists of:[Image: R]Latex Reagent: Suspension of polystyrene latex particles coated withpurified mouse monoclonal anti-PF4-Heparin in Tris buffer,containing bovine serum albumin, stabilizers and preservative.[Image: S]Stabilizer: PBS buffer containing bovine serum albumin, stabilizersand preservative.[Image: Com]Complex: Solution of PF4-PVS complex (PF4 from human plateletscomplexed to PVS), in PBS buffer containing bovine serum albumin,stabilizers and preservative. Contains 0.02% Bronidox™ as apreservative.[Image: C]Calibrator: Lyophilized solution of a monoclonal anti- PF4-Heparinantibody in Tris buffer containing bovine serum albumin, stabilizersand preservative. |
| Controls | The Low and High HIT-Ab(PF4-H) Controls are prepared by means of adedicated process and contain different concentrations of humanizedmonoclonal anti-PF4-Heparin-human IgG.Low HIT-Ab(PF4-H) Control: Control intended for the assessment of precisionand accuracy of the assay at PF4/H antibody levels at or below the cut-off.High HIT-Ab(PF4-H) Control: Control intended for the assessment of precisionand accuracy of the assay at abnormal PF4/H antibody levels.Use of both controls is recommended for a complete quality controlprogram. |
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| Comparison to Predicate | ||
|---|---|---|
| Item | Predicate | New Device |
| Trade Names | Asserachrom HPIA Test Kit(Kit Includes 2 Control Levels) | HemosIL HIT-Ab(PF4-H)HemosIL HIT-Ab(PF4-H) Controls |
| Manufacturer | Diagnostica Stago | Instrumentation Laboratory Co. |
| Similarities | ||
| Measurand | Anti-PF4/Heparin Total Antibodies | Same |
| Assay Type | Qualitative | Same |
| Detection Method | Absorbance (Colorimetric) | Absorbance (Turbidimetric) |
| Product Code | LCO | Same |
| Regulation Section | 864.7695 | Same |
| Classification | Class II | Same |
| Intended Use | The ASSERACHROM® HPIA Test Kit isintended for use as a qualitativeprocedure for the detection of anti-heparin-platelet factor 4 (anti-Heparin-PF4) antibodies in citratedplasma or serum by the sandwichtechnique of enzyme-linkedimmunosorbent assay (ELISA).The presence in plasma or serum ofanti-Heparin-PF4 antibodies,together with a concurrent drop inplatelet count, is generallyassociated with Type II heparin-induced thrombocytopenia (Type IIHIT), a condition that occurs duringheparin therapy, leading to arterialor venous thrombosis. | HemosIL HIT-Ab(PF4-H) is a qualitative,fully automated, latex enhancedimmunoassay for the detection of anti-platelet factor 4/heparin (PF4/H)antibodies. The assay is for use inhuman 3.2% or 3.8% citrated plasmaon the ACL TOP® Family of instrumentsin a laboratory setting.The result provided by the assay shouldbe interpreted as either positive ornegative based on the assay cut-off(1.0 U/mL). The positive or negativeresult aids in determining the risk forheparin induced thrombocytopenia(HIT) when used in conjunction withother laboratory and clinical findings.Anti-PF4/Heparin antibodies arecommonly found in patients with HIT.For use in adult population suspectedof HIT. Not for use in isolation toexclude HIT.HemosIL HIT-Ab(PF4-H) Controls are forthe Quality Control of the HemosIL HIT-Ab(PF4-H) assay as performed on the ACLTOP Family of instruments.For prescription use. |
| Differences | ||
| Methodology | Two-step enzyme immunoassay(ELISA) sandwich method with afinal colorimetric detection. | Latex-enhanced immuno-turbidimetric assay. |
| Sample Types | Citrated Human Plasma or Serum | Citrated Human Plasma Only |
| Antibodies | Goat anti-human antibodies toIgG, IgA and IgM | Purified mouse monoclonalanti-PF4-Heparin |
| Cut-off | Variable clinical cut-offCut-off is lot and plate dependent.Every time a plate is processed, thecut-off for this plate is calculated asthe percentage (X%) of the valueobtained for the Reagent 6 suppliedwith the kit. This percentage isprovided for each lot through theinsert sheets. | Fixed clinical cut-off: ≥ 1.0 U/mL |
| Controls | Controls included in test kit:• Negative level• Positive level | Controls sold separately:• Low Level at or below the cut-off• High Level at abnormalanti-PF4/H antibody level. |
| Calibrator Traceability | Not Applicable | The reported values for the kitcalibrator are determined overmultiple runs on the ACL TOP Familyof instruments using specific lots ofreagents and against an internalHouse Standard. Since a HITInternational Standard is notcurrently available, Arbitrary Units(U/ml) have been established. |
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Performance Summary
Multi-Reagent Lot Precision
An internal precision study was performed using three (3) different lots of HemosIL HIT-Ab(PF4-H) reagents run on a representative ACL TOP Family member (ACL TOP 700). The study used a single lot of HemosL HIT-Ab(PF4-H) Controls (low and high), as well as five (5) patient pools prepared at different levels to span the assay range. Each material was tested with each reagent lot in duplicate, twice a day for 20 days, for a total of 80 replicates per level per lot as summarized below:
| Reagent Lot No. 1 | |||
|---|---|---|---|
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
| Low HIT-Ab(PF4-H) Control | 0.8 | 9.0 | 9.9 |
| High HIT-Ab(PF4-H) Control | 2.5 | 2.6 | 3.3 |
| Plasma Sample 1 | 0.8 | 10.6 | 13.5 |
| Plasma Sample 2 | 1.5 | 3.8 | 4.3 |
| Plasma Sample 3 | 3.3 | 3.0 | 4.5 |
| Plasma Sample 4 | 9.2 | 3.0 | 3.8 |
| Plasma Sample 5 | 15.3 | 3.4 | 4.3 |
| Reagent Lot No. 2 | |||
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
| Low HIT-Ab(PF4-H) Control | 0.7 | 7.9 | 9.3 |
| High HIT-Ab(PF4-H) Control | 2.5 | 3.1 | 3.9 |
| Plasma Sample 1 | 0.8 | 9.0 | 11.1 |
| Plasma Sample 2 | 1.5 | 3.9 | 4.4 |
| Plasma Sample 3 | 3.4 | 7.2 | 7.2 |
| Plasma Sample 4 | 8.8 | 2.9 | 3.6 |
| Plasma Sample 5 | 14.7 | 4.8 | 5.3 |
| Reagent Lot No. 3 | |||
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
| Low HIT-Ab(PF4-H) Control | 0.7 | 8.4 | 9.9 |
| High HIT-Ab(PF4-H) Control | 2.3 | 3.5 | 4.0 |
| Plasma Sample 1 | 0.7 | 10.1 | 10.2 |
| Plasma Sample 2 | 1.4 | 3.8 | 4.7 |
| Plasma Sample 3 | 3.0 | 4.4 | 5.9 |
| Plasma Sample 4 | 8.3 | 2.3 | 3.8 |
| Plasma Sample 5 | 13.3 | 3.2 | 4.3 |
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| Aggregated data (Reagent Lots 1, 2 and 3) | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Material | Mean(U/mL) | Lot-to-Lot Variability%CV | ||||||||
| Low HIT-Ab(PF4-H) Control | 0.7 | 4.1 | ||||||||
| High HIT-Ab(PF4-H) Control | 2.4 | 3.7 | ||||||||
| Plasma Sample 1 | 0.8 | 5.2 | ||||||||
| Plasma Sample 2 | 1.5 | 6.3 | ||||||||
| Plasma Sample 3 | 3.3 | 6.1 | ||||||||
| Plasma Sample 4 | 8.8 | 5.3 | ||||||||
| Plasma Sample 5 | 14.4 | 7.2 |
Multi-Reagent Lot Site-to-Site Reproducibility
Reproducibility studies were conducted at three (3) external clinical sites by three (3) different operators (one operator per site), on three (3) different ACL TOP 500 CTS instrument per site), using three (3) different lots of HemosIL HIT-Ab(PF4-H) reagents and HemosIL HIT-Ab(PF4-H) Controls (low and high). To span the assay range, three (3) patient pools (2 positive) and a manufactured material containing a citrated plasma sample spiked with monoclonal anti-PF4-Heparin antibody were also tested (Plasma Sample 4)
Each material was tested in triplicate, twice a day for 5 days, for a total of 30 replicates per level.
The pooled data for each reagent lot are summarized below and on the next page:
| Pooled 3-Site Data: Reagent Lot 1 of HemosIL HIT-Ab(PF4-H) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | Mean | Repeatability(within-run) | Between-Run | Between-Day | Between Site | Reproducibility(Total) | |||||
| (U/mL) | SD | % CV | SD | % CV | SD | % CV | SD | %CV | SD | % CV | |
| Low HIT-Ab(PF4-H) Control | 0.9 | 0.11 | 11.7 | 0.07 | 7.1 | 0.00 | 0.0 | 0.06 | 6.7 | 0.14 | 15.3 |
| High HIT-Ab(PF4-H) Control | 2.6 | 0.13 | 5.1 | 0.06 | 2.1 | 0.07 | 2.7 | 0.00 | 0.0 | 0.16 | 6.1 |
| Plasma Sample 2 | 2.1 | 0.11 | 5.2 | 0.08 | 3.9 | 0.00 | 0.0 | 0.05 | 2.2 | 0.14 | 6.8 |
| Plasma Sample 3 | 4.0 | 0.21 | 5.2 | 0.05 | 1.2 | 0.12 | 2.9 | 0.00 | 0.0 | 0.25 | 6.1 |
| Plasma Sample 4 | 13.4 | 0.88 | 6.5 | 0.00 | 0.0 | 0.33 | 2.5 | 0.73 | 5.5 | 1.19 | 8.9 |
| Level | Mean(U/mL) | Result | |||||||||
| Plasma Sample 1 | 0.4 | All Replicates < 1.0 U/mL |
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| Pooled 3-Site Data: Reagent Lot 2 of HemosIL HIT-Ab(PF4-H) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | Mean | Repeatability(within-run) | Between-Run | Between-Day | Between Site | Reproducibility(Total) | |||||
| (U/mL) | SD | % CV | SD | % CV | SD | % CV | SD | % CV | SD | % CV | |
| Low HIT-Ab(PF4-H) Control | 0.9 | 0.08 | 9.2 | 0.02 | 2.8 | 0.00 | 0.0 | 0.05 | 6.1 | 0.06 | 7.4 |
| High HIT-Ab(PF4-H) Control | 2.6 | 0.09 | 3.4 | 0.05 | 1.9 | 0.02 | 0.8 | 0.13 | 4.8 | 0.13 | 5.2 |
| Plasma Sample 2 | 1.9 | 0.08 | 4.2 | 0.03 | 1.4 | 0.00 | 0.0 | 0.04 | 1.8 | 0.04 | 2.3 |
| Plasma Sample 3 | 3.9 | 0.17 | 4.3 | 0.08 | 2.1 | 0.00 | 0.0 | 0.31 | 7.9 | 0.32 | 8.1 |
| Plasma Sample 4 | 12.5 | 0.56 | 4.5 | 0.33 | 2.6 | 0.01 | 0.1 | 0.70 | 5.6 | 0.77 | 6.2 |
| Level | Mean(U/mL) | Result | |||||||||
| Plasma Sample 1 | 0.3 | All Replicates < 1.0 U/mL |
| Pooled 3-Site Data: Reagent Lot 3 of HemosIL HIT-Ab(PF4-H) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean(U/mL) | Repeatability(within-run) | Between-Run | Between-Day | Between Site | Reproducibility(Total) | ||||||
| Level | SD | % CV | SD | % CV | SD | % CV | SD | % CV | SD | % CV | |
| Low HIT-Ab(PF4-H) Control | 0.8 | 0.07 | 8.8 | 0.06 | 6.5 | 0.00 | 0.0 | 0.00 | 0.0 | 0.09 | 11.0 |
| High HIT-Ab(PF4-H) Control | 2.7 | 0.11 | 4.0 | 0.06 | 2.1 | 0.00 | 0.0 | 0.08 | 3.1 | 0.15 | 5.5 |
| Plasma Sample 2 | 1.7 | 0.09 | 5.3 | 0.02 | 1.1 | 0.07 | 3.7 | 0.04 | 2.2 | 0.12 | 6.9 |
| Plasma Sample 3 | 3.5 | 0.17 | 4.8 | 0.09 | 0.2 | 0.03 | 0.8 | 0.17 | 4.8 | 0.24 | 6.8 |
| Plasma Sample 4 | 11.8 | 0.61 | 5.1 | 0.11 | 0.9 | 0.00 | 0.0 | 0.58 | 4.9 | 0.85 | 7.2 |
| Level | Mean(U/mL) | Result | |||||||||
| Plasma Sample 1 | 0.2 | All Replicates < 1.0 U/mL |
Multi-Control Lot Precision
An internal precision study was performed using three (3) different lots of HemosIL HIT-Ab(PF4-H) Controls (low and high) run on a representative ACL TOP Family member (ACL TOP 700), with a single lot of HemoslL HIT-Ab(pf4-h) reagents.
Each level of control material from each lot was tested in duplicate, twice a day for 20 days, for a total of 80 replicates per level per lot as summarized below:
| Material | Mean (U/mL) | Within Run (Repeatability) % CV | Total (Within Device) % CV |
|---|---|---|---|
| Low HIT-Ab(PF4-H) Control Lot No. 1 | 0.8 | 9.0 | 9.9 |
| High HIT-Ab(PF4-H) Control Lot No. 1 | 2.5 | 2.6 | 3.3 |
| Low HIT-Ab(PF4-H) Control Lot No. 2 | 0.8 | 6.6 | 9.2 |
| High HIT-Ab(PF4-H) Control Lot No. 2 | 2.7 | 2.1 | 3.0 |
| Low HIT-Ab(PF4-H) Control Lot No. 3 | 0.9 | 6.9 | 8.9 |
| High HIT-Ab(PF4-H) Control Lot No. 3 | 2.7 | 2.1 | 2.6 |
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Multi-Control Lot Reproducibility
Reproducibility studies were conducted at three external clinical sites using different operators, on three different ACL TOP 500 CTS instruments, using three different lots of HemoslL HIT-Abperay, reagents and HemosIL HIT-Abperen Controls (low and high). Each material was tested in triplicate, twice a day for 5 days, for a total of 30 replicates per level. The pooled 3-site data for a representative reagent lot is presented below.
| Pooled 3-Site Data | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | Mean(U/mL) | Repeatability(within-run) | Between-Run | Between-Day | BetweenSite | Reproducibility(Total) | |||||
| SD | % CV | SD | % CV | SD | % CV | SD | %CV | SD | % CV | ||
| Low HIT-Ab(PF4-H) Control | 0.9 | 0.11 | 11.7 | 0.07 | 7.1 | 0.00 | 0.0 | 0.06 | 6.7 | 0.14 | 15.3 |
| High HIT-Ab(PF4-H) Control | 2.6 | 0.13 | 5.1 | 0.06 | 2.1 | 0.07 | 2.7 | 0.00 | 0.0 | 0.16 | 6.1 |
Multi-Calibrator Lot Precision
An internal precision study was performed using three (3) different lots of HemoslL HIT-Ab(PF4-H) Calibrator (kit component from 3 different reagent lots) run on a representative ACL TOP Family member (ACL TOP 700), with a single lot of HemosIL HIT-Ablere-m reagents (with a different kit Calibrator lot).
Each calibrator lot was tested in duplicate, twice a day for 20 days, for a total of 80 replicates per lot as summarized below:
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
|---|---|---|---|
| Kit Calibrator Lot No. 1 | 5.6 | 0.7 | 1.4 |
| Kit Calibrator Lot No. 2 | 5.6 | 1.2 | 1.5 |
| Kit Calibrator Lot No. 3 | 5.6 | 0.6 | 1.9 |
Unadulterated Patient Plasma Precision
An internal unadulterated (unmodified) patient plasma study was performed on a representative ACL TOP Family member (ACL TOP 700). The two (2) patient samples used in the study were collected at a hospital in the United States, with aliquots prepared and maintained at -70°C until use.
Each sample aliguot was tested in duplicate, twice a day for 10 days, for a total of 40 replicates per patient plasma sample as summarized below:
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
|---|---|---|---|
| Patient Plasma Sample 1 | 2.1 | 3.0 | 5.4 |
| Patient Plasma Sample 2 | 8.6 | 5.7 | 6.2 |
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Instrument Model Equivalency
An instrument model equivalency study was performed using fifty-one (51) citrated plasma samples from individual clinical patients who were suspected of having HIT. Each clinical sample was analyzed in singlicate with a single lot of HemosIL HIT-Ab(PF4-H) reagents on representative ACL TOP Family members: ACL TOP 700, ACL TOP 500 CTS and ACL TOP 300 CTS.
NOTE: Samples were distributed along the measuring range.
The reported values of the clinical sample results on ACL TOP 700 were plotted on a X-Y graph comparing the results obtained on the ACL TOP 700 to the ACL TOP 500 CTS and the ACL TOP 300 CTS results as summarized below:
| Instrument | Slope(95% CI) | Intercept(95% CI) | r(95% CI) |
|---|---|---|---|
| ACL TOP 700 vs. ACL TOP 500 CTS | 0.97(0.92 to 1.02) | 0.14(0.05 to 0.23) | 0.9947(0.9909 to 0.9969) |
| ACL TOP 700 vs. ACL TOP 300 CTS | 1.03(1.00 to 1.06) | -0.13(-0.20 to -0.10) | 0.9981(0.9966 to 0.9989) |
The Bland-Altman plot of the 95% limits of agreement between the ACL TOP Instruments supported that the instrument models provide statistically equivalent results.
Linearity and Test Ranges
A linearity study was performed using two (2) lots of HemosIL HIT-Ab(PF4-H) reagents, with each lot tested on three (3) representative ACL TOP Family members: ACL TOP 500 CTS and ACL TOP 300 CTS.
Two (2) positive patient samples were spiked into donor plasma from a blood bank to prepare 10 concentrations ranging across the standard measurement range (0.6-5.7 U/mL). A third extremely high positive patient sample was used to prepare samples with concentrations ranging across the auto re-run linear range (2.1 to 16.0 U/mL).
The results support the following linearity claims:
Linearity Range:
| Auto Rerun off | Auto Rerun on | |
|---|---|---|
| ACL TOP Family | 0.6 – 5.7 U/mL | 2.1 – 16.0 U/mL |
Test Range:
| Auto Rerun off | Auto Rerun on | |
|---|---|---|
| ACL TOP Family | 0 – 5.7 U/mL | 0 – 16.0 U/mL |
Result Interpretation
HIT-Ab(PF4-H) results are reported in U/mL (HemoslL HIT-Ab(PF4-H) Arbitrary Units) on the ACL TOP Family instruments as follows:
| System | Results | Interpretation |
|---|---|---|
| ACL TOP Family | ≥ 1.0 U/mL | HIT Antibody positive |
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IMPORTANT: The laboratory should report only the interpreted result (HIT Antibody positive or negative) to the clinician as the final reported result.
The positive or negative result should be used with other information, including the clinical context, in forming a diagnosis such as the 4T score and the 2013 American Society of Hematology guidelines.
Although a positive result obtained using this assay may indicate the presence of heparin-associated antibodies, a positive result DOES NOT CONFIRM the diagnosis of HIT. Some patients may have naturally occurring antibodies to PF4.
Interferences / Limitations
Interferences .
Testing confirmed no interference for the HemosIL HIT-Ab(PF4-H) assay on the ACL TOP Family up to the following concentrations:
| Hemoglobin | Bilirubin | Triglycerides | RheumatoidFactor | HAMA |
|---|---|---|---|---|
| 500 mg/dL | 19 mg/dL | 375 mg/dL | 1000 IU/mL | 1 µg/mL |
. Heparin Sensitivity
One hundred twenty-six (126) citrated plasma samples from non-HIT suspected, heparin treated patients (either UFH or LMWH) were tested with the HemosIL HIT-Abperin assay. For LMWH, 115 samples with a heparin concentration range between 0-2.47 IU/mL. For UFH, 11 samples with a heparin concentration range between 0.04-1.08 IU/mL.
There was no dose-response correlation between the HIT results and heparin (UFH and LMWH) concentrations.
Antiphospholipid Syndrome (APS) .
Forty (40) citrated plasma samples from patients who were diagnosed with Antiphospholipid Syndrome (APS) were tested with the HemosIL HIT-Ab(PF4-H) assay. All 40 samples reported negative with HemosIL HIT-Ab(PF4-H), demonstrating that the assay is not affected by antiphospholipid antibodies.
Reference Interval – Healthy Donors
A population of one hundred thirty-one (131) citrated plasma samples from apparently healthy individuals was tested with the HemosIL HIT-Ab(PF4-H) assay.
The upper limit of the reference interval was established as 0.7 U/mL (90% Cl: 0.60-0.71 U/mL).
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Reference Interval – Heparin Exposed, HIT Suspected Patients (HIT Negative)
A population of one hundred twenty-two (122) citrated plasma samples from HIT-suspected, but negative by a commercially available ELISA was tested with the HemosIL HIT-Ab(PF4-H) assay. The upper limit of the reference interval was established as 0.9 U/mL (90% Cl: 0.80-1.03 U/mL).
Cut-Off Determination
Sixty three (63) citrated plasma samples were obtained from hospitalized patients who had been exposed to heparin, and who displayed clinical signs consistent with Heparin Induced Thrombocytopenia (HIT). These patients were tested by the hospital with the Serotonin Release Assay (SRA) and the sample results (31 SRA positive and 32 SRA negative) were used to perform a Receiver Operating Characteristics (ROC) analysis to determine the clinical cut-off for HemosIL HIT-Ablpp4-H)-
The optimal cut-off as determined by ROC analysis was 1.0 U/mL (95.2% Agreement; CI% = 86.7% - 99.0%).
Method Comparison Definitions and Formulas
See below 2x2 contingency table with definitions and formulas.
| Reference | |||||||
|---|---|---|---|---|---|---|---|
| + | - | TP | True Positives | ||||
| + | TP | FP | TN | True Negatives | |||
| Test | - | FN | TN | FP | False Positives | ||
| FN | False Negatives | ||||||
| Positive Percent AgreementNegative Percent Agreement | $PPA = \frac{TP}{TP + FN}$ | $NPA = \frac{TN}{TN + FP}$ |
| Negative Predictive Value | $PPV = \frac{TP}{TP + FP}$ | $NPV = \frac{TN}{TN + FN}$ |
|---|---|---|
| Positive Predictive Value |
$$\textbf{TPA} \qquad \textbf{Total PercentAgreement} \qquad \qquad TPA \quad = \frac{TP + TN}{TP + TN + FP + FN}$$
Method Comparison (Internal)
An internal method comparison study was performed to compare the performance of the new Hemos L HIT-Ab(PF4-H) assay versus its predicate, the Asserachrom HPIA Test Kit (K003767), on a representative member of the ACL TOP Family (ACL TOP 700 model).
A total of 118 frozen citrated patient plasma samples from patients referred for HIT testing were obtained from a hospital in the US and a hospital in France. Samples were analyzed in singlicate, with no spiked samples used in this study.
The results summarized below are based on a cut-off of 1.0 U/mL for the HemosIL HIT-Ab(PF4-H) assay and the lot- and plate-dependent cut-off for the Asserachrom HPIA Test Kit.
PPA NPA
NPV
PPV
{14}------------------------------------------------
| HPIA ELISA results | ||||
|---|---|---|---|---|
| + | - | Total | ||
| HemosIL HIT-Ab(PF4-H)results | + | 68 | 8 | 76 |
| - | 13 | 29 | 42 | |
| Total | 81 | 37 | 118 |
| HemosIL HIT-Ab(PF4-H) vs Asserachrom HPIA | Proportion | Wilson 95% CI | |
|---|---|---|---|
| PPA (Positive Percent Agreement) | 84% (68/81) | 74% | 91% |
| NPA (Negative Percent Agreement) | 78% (29/37) | 62% | 90% |
| Total Percent Agreement | 82% (97/118) | 74% | 89% |
Multicenter Method Comparison
A multicenter method comparison study was conducted at three (3) hospitals on 632 patient samples, comparing the performance of the new HemosIL HIT-Aber4-with the predicate device, the Asserachrom HPIA Test Kit (K003767) and with the reference device, Serotonin Release Assay (SRA). The samples were from patients exposed to heparin who showed HIT related symptoms. Samples were analyzed in singlicate, with no spiked samples used in this study.
HemosIL HIT-Ab(PF4-H) Assay vs. Predicate Device (Asserachrom HPIA Test Kit)
The pooled results below are based on a cut-off of 1.0 U/mL for the HemosIL HIT-Ab(PF4-H) assay and the lotand plate-dependent cut-off for the Asserachrom HPIA Test Kit.
| HPIA ELISA results | ||||
|---|---|---|---|---|
| + | - | Total | ||
| HemosIL HIT-Ab(PF4-H)results | + | 67 | 39 | 106 |
| - | 22 | 504 | 526 | |
| Total | 89 | 543 | 632 |
| HemosIL HIT-Ab(PF4-H) vs Asserachrom HPIA | Proportion | Wilson 95% CI | |
|---|---|---|---|
| PPA (Positive Percent Agreement) | 75% (67/89) | 65% | 83% |
| NPA (Negative Percent Agreement) | 93% (504/543) | 90% | 95% |
| Total Percent Agreement | 90% (571/632) | 88% | 92% |
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HemosIL HIT-Ab(PF4-H) Assay vs. SRA and Predicate vs. SRA
Patient samples in the multicenter study without a valid SRA result or with an indeterminate result (total N=95) were removed from calculations, bringing the final total to N = 537.
The pooled results summarized below compare both HemosIL HIT-Ab(PF4-H) assay results (cut-off of 1.0 U/mL) to the SRA test results and the Asserachrom HPIA Test Kit (lot- and plate-dependent cut-off) to the SRA test results.
- HemosIL HIT-Ab(PF4-H) Assay vs. SRA:
| SRA Results | ||||
|---|---|---|---|---|
| + | - | Total | ||
| HemosIL HIT-Ab(PF4-H)results | + | 33 | 56 | 89 |
| - | 59 | 389 | 448 | |
| Total | 92 | 445 | 537 |
| HemosIL HIT-Ab(PF4-H) vs SRA | Proportion | Wilson 95% CI |
|---|---|---|
| PPV (Positive Predictive Value) | 37% (33/89) | 28% 47% |
| NPV (Negative Predictive Value) | 87% (389/448) | 83% 90% |
- Asserachrom HPIA Test Kit (Predicate) vs. SRA: ●
| SRA Results | ||||
|---|---|---|---|---|
| + | - | Total | ||
| HPIA ELISA results | + | 31 | 37 | 68 |
| - | 61 | 408 | ||
| Total | 92 | 445 |
| Asserachrom HPIA vs SRA | Proportion | Wilson 95% CI |
|---|---|---|
| PPV (Positive Predictive Value) | 46% (31/68) | 34% 57% |
| NPV (Negative Predictive Value) | 87% (408/469) | 84% 90% |
Conclusion: The diagnostic performance of the HemosIL HIT-Ab(PF4-H) assay was equivalent to the Asserachrom HPIA Test Kit (predicate) when compared to SRA test results.
{16}------------------------------------------------
HemosIL HIT-Ablprach Assay vs. 2013 American Society of Hematology (ASH) Guidelines
The results summarized below are based on the 2013 ASH guideline for determining clinical probability. The ASH diagnostic algorithm classifies samples as HIT Likely or HIT Unlikely based on a clinical probability score (i.e. patient 4T score), the Asserachrom HPIA Test Kit (as the ELISA result) and the SRA results (as the functional assay). In this retrospective study using the multicenter data, the results of the ASH diagnostic algorithm were compared with the data obtained with HemosIL HIT-Ab(PF4-H).
NOTE: The performance results are not based on a confirmed diagnosis of HIT.
| Clinical ProbabilityAccording to 2013 ASH | ||||
|---|---|---|---|---|
| HIT Likely | HIT Unlikely | Total | ||
| HemosIL HIT-Ab(PF4-H)results | + | 17 | 72 | 89 |
| - | 2 | 446 | 448 | |
| Total | 19 | 518 | 537 |
| Clinical Probability according to ASH 2013 | Proportion | Wilson 95% CI | |
|---|---|---|---|
| PPA (Positive Percent Agreement) | 89% (17/19) | 69% | 97% |
| NPA (Negative Percent Agreement) | 86% (446/518) | 83% | 89% |
| Clinical Probability according to ASH 2013 | Proportion | Wilson 95% CI | |
|---|---|---|---|
| PPV (Positive Predictive Value) | 19% (17/89) | 12% | 28% |
| NPV (Negative Predictive Value) | 100% (446/448) | 98% | 100% |
Conclusion:
The analytical and clinical study results demonstrate that the HemosIL HIT-Ab(PF4-H) assay and HemosIL HIT-Ab(PF4-H) Controls are substantially equivalent to the predicate device, Asserachrom HPIA Test Kit (FDA cleared under K003767), and that the assay is safe and effective for its labeled intended use when compared to the SRA reference method.
§ 864.7695 Platelet factor 4 radioimmunoassay.
(a)
Identification. A platelet factor 4 radioimmunoassay is a device used to measure the level of platelet factor 4, a protein released during platelet activation by radioimmunoassay. This device measures platelet activiation, which may indicate a coagulation disorder, such as myocardial infarction or coronary artery disease.(b)
Classification. Class II (performance standards).