(170 days)
HemosIL AcuStar HIT-IgG(PF4-H) is a qualitative, fully automated, chemiluminescent immunoassay (CIA) for the detection of IgG antibodies that react with Platelet Factor 4 (PF4) when complexed to heparin. The assay is for use in human 3.2% or 3.8% citrated plasma and serum on the ACL AcuStar instrument in a laboratory setting.
The result provided by the assay should be interpreted as either positive or negative based on the assay cut-off (1.00 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 AcuStar HIT Controls are for the quality control of the HemosIL AcuStar HIT-IgG(PF4-H) assay as performed on the ACL AcuStar.
For prescription use.
The HemosIL AcuStar HIT-IgG(PF4-H) assay is a chemiluminescent two-step immunoassay consisting of magnetic particles coated with PF4 complexed to polyvinyl sulfonate (PVS) which capture, if present, the PF4/Heparin antibodies from the sample. After incubation, magnetic separation, and a wash step, a tracer consisting of an isoluminol-labeled anti-human IgG antibody is added and may bind with the captured PF4/Heparin IgG on the particles. After a second incubation, magnetic separation, and a wash step, reagents that trigger the luminescent reaction are added, and the emitted light is measured as relative light units (RLUs) by the ACL AcuStar optical system. The RLUs are directly proportional to the PF4/Heparin IgG concentration in the sample.
The HemosIL AcuStar HIT-IgG(PF4-H) kit consists of:
R HIT-IgG(PF4-H) Cartridge for 25 determinations: Cartridge containing 1 vial of magnetic particle suspension coated with PF4/PVS complex, 1 vial of assay buffer, 1 vial of tracer consisting of an mAb anti-human IgG antibody labeled with isoluminol, and 1 vial of sample diluent used for the regular predilution of the sample. The reagents are in a phosphate or Tris buffer containing bovine serum albumin, bovine fetal serum, PF4/PVS complex, mouse monoclonal IgG, stabilizers, and preservative.
C1 HIT-IgG(PF4-H) Calibrator 1: Barcoded tube of a solution with humanized mAb anti-PF4-Heparin in Tris buffer containing bovine serum albumin, stabilizers and preservative.
C2 HIT-IgG(PF4-H) Calibrator 2: Barcoded tube of a solution with humanized mAb anti-PF4-Heparin in Tris buffer containing bovine serum albumin, stabilizers, and preservative.
The calibrators are lot specific and they cannot be used with other lots of reagents.
Controls:
The Low and High HIT Controls are prepared by means of a dedicated process and contain different concentrations of humanized monoclonal anti-PF4-Heparin.
Low HIT Control: Control intended for the assessment of precision and accuracy of the HemosIL AcuStar HIT-IgG(PF4-H) assay below the cut-off.
High HIT Control: Control intended for the assessment of precision and accuracy of the HemosIL AcuStar HIT-IgG(PF4-H) assay above the cut-off.
Use of both controls is recommended for a complete quality control program.
Here's a breakdown of the acceptance criteria and the study details for the HemosIL AcuStar HIT-IgG(PF4-H) device, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
The document doesn't explicitly state "acceptance criteria" for all performance metrics in a pass/fail format. However, by comparing the device to the predicate and the SRA, and given the FDA clearance, a reasonable inference of acceptable performance can be made from the reported results. The critical performance metrics are related to agreement with the predicate device and a reference method (SRA).
| Metric / Aspect | Implicit Acceptance Criteria / Goal | Reported Device Performance (HemosIL AcuStar HIT-IgG(PF4-H)) |
|---|---|---|
| Vs. Predicate Device (Zymutest HIA IgG) | ||
| Positive Percent Agreement (PPA) | Comparable to predicate for substantial equivalence | 35% (26/74) with Wilson 95% CI: 25%-47% |
| Negative Percent Agreement (NPA) | High, comparable to predicate for substantial equivalence | 99% (719/728) with Wilson 95% CI: 98%-99% |
| Total Percent Agreement | High, comparable to predicate for substantial equivalence | 93% (745/802) with Wilson 95% CI: 91%-94% |
| Vs. Serotonin Release Assay (SRA) | ||
| Positive Predictive Value (PPV) | High and superior to predicate | 76% (26/34) with Wilson 95% CI: 60%-88% |
| Negative Predictive Value (NPV) | High and equivalent to predicate | 98% (741/756) with Wilson 95% CI: 97%-99% |
| Total Percent Agreement | High | 97% (767/790) with Wilson 95% CI: unclear (text has "रिके%") |
| Precision (Internal Study) | Various CV% targets for repeatability, within device, lot-to-lot, etc. | Varies by sample and lot; e.g., Plasma Sample 1 (Pool) Total CV: 8.3% (Lot 1), 9.2% (Lot 2), 13.8% (Lot 3) |
| Cut-off Precision (Internal Study) | Various CV% targets for within-run, between-run, between-day, etc. | Varies by sample; e.g., Sample 1 Total CV: 10.0%, Sample 2 Total CV: 7.1%, Sample 3 Total CV: 6.4% |
| Reproducibility (Multisite Study) | Various CV% targets for repeatability, between-run, between-day, between-site, and total reproducibility. | Varies by control/sample and lot; e.g., Low HIT Control total reproducibility CV: 10.7% (Lot 1), 8.2% (Lot 2), 7.2% (Lot 3) |
| Interference | No interference up to specified concentrations | No interference up to: Hemoglobin 500 mg/dL, Bilirubin 18 mg/dL, Triglycerides 1250 mg/dL, Heparin 1 IU/mL, HAMA 1 µg/mL |
| Antiphospholipid Syndrome (APS) | Not affected by APS antibodies | All 26 APS samples reported as negative |
2. Sample Sizes Used for the Test Set and Data Provenance
- Multicenter Method Comparison (vs. Predicate and SRA):
- Sample Size:
- N=802 for comparison to predicate (Zymutest HIA IgG).
- N=790 for comparison to Serotonin Release Assay (SRA). (12 samples removed due to invalid/indeterminate SRA results).
- Data Provenance: Samples were obtained from patients exposed to heparin and showing HIT-related symptoms. The study was conducted at three (3) external clinical sites (hospitals). This indicates a prospective clinical study environment across multiple locations, likely within the country where the study was performed (not explicitly stated, but typically FDA submissions refer to studies conducted in, or acceptable to, the US or EU). The status is prospective in the sense that these were newly tested samples within the framework of this study, even if collected from ongoing patient care.
- Sample Size:
- Precision and Reproducibility Studies: Sample pools and native patient samples were used. Actual number of unique patient samples used for these studies is not explicitly stated, but the studies involve repeated testing of these samples.
- Cut-off Determination: 87 citrated plasma samples from hospitalized patients exposed to heparin and with clinical signs consistent with HIT.
- Reference Intervals:
- Heparin Exposed, Non-HIT Suspected: 91 citrated plasma samples.
- Healthy Donors: 154 citrated plasma samples.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
- For Cut-off Determination: The Serotonin Release Assay (SRA) served as the reference method (ground truth). It is implied that the SRA results themselves were established by experts in the hospitals where the samples were tested. No specific number or qualifications of experts are given in this document.
- For Multicenter Method Comparison: The SRA was again used as the primary reference method ("gold standard"). The results of the SRA are taken as the ground truth. There is no mention of an expert panel specifically adjudicating the SRA results or the clinical diagnoses used in the study.
4. Adjudication Method for the Test Set
- No explicit adjudication method (e.g., 2+1) is described for the test set of the primary clinical study.
- The comparison relies directly on the results of the Serotonin Release Assay (SRA) as the reference standard, and the predicate device.
- The "cut-off determination" section mentions that the 87 samples were tested by the hospital with SRA, and these results (45 SRA positive, 42 SRA negative) were used to perform ROC analysis to establish the device's cut-off. This suggests the SRA results are considered the definitive truth.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size
- No, an MRMC comparative effectiveness study was not done. This device is an in vitro diagnostic (IVD) immunoassay, not an imaging or interpretive device that typically involves human readers in the output interpretation directly. The output is a numerical value (U/mL) and a categorical interpretation (Positive/Negative) which is then used by clinicians. There is no "human-in-the-loop" component in the sense of interpreting the AI's output in comparison to interpreting raw data.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Yes, the provided performance data represents the standalone performance of the HemosIL AcuStar HIT-IgG(PF4-H) assay. This is an automated immunoassay where the instrument and reagents perform the analytical steps and output the result (U/mL) and interpretation (Positive/Negative). There is no "human-in-the-loop" interaction with the algorithm's immediate output that would alter its performance metrics as presented here.
7. The Type of Ground Truth Used
- Serotonin Release Assay (SRA) results were used as the primary reference method or "gold standard" for establishing clinical performance (e.g., PPV, NPV, and cut-off determination).
- The predicate device (Zymutest HIA IgG) was also used as a comparator for demonstrating substantial equivalence.
8. The Sample Size for the Training Set
- The document does not explicitly mention a "training set" in the context of machine learning or AI algorithm development. This device is an IVD immunoassay, and its development follows more traditional analytical validation processes rather than AI model training.
- However, the "Cut-Off Determination" study, which involved 87 samples with known SRA results, effectively served a similar purpose to a training/validation set in establishing an optimal operating point (the 1.00 U/mL cut-off) for the device. These patients had been exposed to heparin and displayed clinical signs consistent with HIT.
- The "Reference Interval" studies (healthy donors and heparin-exposed non-HIT suspected patients) also contribute to understanding the assay's behavior in different populations, which could be seen as part of foundational data.
9. How the Ground Truth for the Training Set Was Established
- As noted above, for the "Cut-Off Determination" study (serving a similar role to a training set), the ground truth for the 87 samples was established by Serotonin Release Assay (SRA) results performed by the hospital. The results were categorized as SRA positive (45 samples) and SRA negative (42 samples). These SRA classifications then allowed for Receiver Operating Characteristics (ROC) analysis to determine the optimal assay cut-off.
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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
September 8, 2017
Instrumentation Laboratory Co. Carol Marble Regulatory Affairs Director 180 Hartwell Road Bedford, Massachusetts 01730
Re: K170854
Trade/Device Name: HemosIL AcuStar HIT-IgGopp4-HemosIL AcuStar HIT Controls Regulation Number: 21 CFR 864.7695 Regulation Name: Platelet factor 4 radioimmunoassay Regulatory Class: Class II Product Code: LCO. GGN Dated: March 21, 2017 Received: March 22, 2017
Dear Carol 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 CFR
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Part 807): labeling (21 CFR Part 801 and Part 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 and Part 809), please contact the Division of Industry and Consumer Education (DICE) 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. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 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 (DICE) 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,
Leonthena R. Carrington -S
Lea Carrington 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) K170854
Device Name HemosIL AcuStar HIT-IgG(PF4-H) HemosIL AcuStar HIT Controls
Indications for Use (Describe)
HemosIL AcuStar HIT-IgG(PF4-H) is a qualitative, fully automated, chemiluminescent immunoassay (CIA) for the detection of IgG antibodies that react with Platelet Factor 4 (PF4) when complexed to heparin. The assay is for use in human 3.2% or 3.8% citrated plasma and serum on the ACL AcuStar instrument in a laboratory setting.
The result provided by the assay should be interpreted as either positive or negative based on the assay cut-off (1.00 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 AcuStar HIT Controls are for the quality control of the HemosIL AcuStar HIT-IgG(PF4-H) assay as performed on the ACL AcuStar.
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 RoadBedford, MA 01730, USA | ||
|---|---|---|---|
| Contact Person | Carol Marble, Regulatory Affairs DirectorPhone: 781-861-4467Fax: 781-861-4207Email: cmarble@ilww.com | ||
| Preparation Date | August 26, 2017 | ||
| Device Trade Names | Reagent Cartridge Kit (with Calibrator) | HemosIL AcuStar HIT-IgG(PF4-H) | |
| Controls | HemosIL AcuStar HIT Controls | ||
| Regulatory Information –Reagent Cartridge 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 | K071255 (Zymutest HIA IgG from HYPHEN Biomed) |
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| Indications for Use /Intended Use | HemosIL AcuStar HIT-IgG(PF4-H) is a qualitative, fully automated, chemiluminescentimmunoassay (CIA) for the detection of IgG antibodies that react with Platelet Factor4 (PF4) when complexed to heparin. The assay is for use in human 3.2% or 3.8%citrated plasma and serum on the ACL AcuStar instrument in a laboratory setting.The result provided by the assay should be interpreted as either positive or negativebased on the assay cut-off (1.00 U/mL). The positive or negative result aids indetermining the risk for heparin induced thrombocytopenia (HIT) when used inconjunction with other laboratory and clinical findings.Anti-PF4/Heparin antibodies are commonly found in patients with HIT. For use in adultpopulation suspected of HIT. Not for use in isolation to exclude HIT.HemosIL AcuStar HIT Controls are for the quality control of the HemosIL AcuStarHIT-IgG(PF4-H) assay as performed on the ACL AcuStar.For prescription use. |
|---|---|
| Device DescriptionReagent Cartridgeswith Calibrators | The HemosIL AcuStar HIT-IgG(PF4-H) assay is a chemiluminescent two-stepimmunoassay consisting of magnetic particles coated with PF4 complexed topolyvinyl sulfonate (PVS) which capture, if present, the PF4/Heparin antibodies fromthe sample. After incubation, magnetic separation, and a wash step, a tracerconsisting of an isoluminol-labeled anti-human IgG antibody is added and may bindwith the captured PF4/Heparin IgG on the particles. After a second incubation,magnetic separation, and a wash step, reagents that trigger the luminescentreaction are added, and the emitted light is measured as relative light units (RLUs)by the ACL AcuStar optical system. The RLUs are directly proportional to thePF4/Heparin IgG concentration in the sample.The HemosIL AcuStar HIT-IgG(PF4-H) kit consists of: |
| R HIT-IgG(PF4-H) Cartridge for 25 determinations: Cartridge containing 1 vial ofmagnetic particle suspension coated with PF4/PVS complex, 1 vial of assaybuffer, 1 vial of tracer consisting of an mAb anti-human IgG antibody labeledwith isoluminol, and 1 vial of sample diluent used for the regular predilutionof the sample. The reagents are in a phosphate or Tris buffer containing bovineserum albumin, bovine fetal serum, PF4/PVS complex, mouse monoclonal IgG,stabilizers, and preservative. | |
| C1 HIT-IgG(PF4-H) Calibrator 1: Barcoded tube of a solution with humanized mAbanti-PF4-Heparin in Tris buffer containing bovine serum albumin, stabilizersand preservative. | |
| C2 HIT-IgG(PF4-H) Calibrator 2: Barcoded tube of a solution with humanized mAbanti-PF4-Heparin in Tris buffer containing bovine serum albumin, stabilizers,and preservative. | |
| The calibrators are lot specific and they cannot be used with other lots of reagents. | |
| Controls | The Low and High HIT Controls are prepared by means of a dedicated process andcontain different concentrations of humanized monoclonal anti-PF4-Heparin. |
| Low HIT Control: Control intended for the assessment of precision and accuracy of theHemosIL AcuStar HIT-IgG(PF4-H) assay below the cut-off. | |
| High HIT Control: Control intended for the assessment of precision and accuracy ofthe HemosIL AcuStar HIT-IgG(PF4-H) assay above the cut-off. | |
| Use of both controls is recommended for a complete quality control program. |
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| Comparison to Predicate | ||
|---|---|---|
| Item | Predicate | New Device |
| Trade Names | Zymutest HIA IgG(Kit Includes 2 Control Levels) | HemosIL AcuStar HIT-IgG(PF4-H)HemosIL AcuStar HIT Controls |
| Manufacturer | HYPHEN Biomed | Instrumentation Laboratory Co. |
| Similarities | ||
| Measurand | Anti-PF4/Heparin IgG Antibodies | Same |
| Assay Type | Qualitative | Same |
| Product Code | LCO | Same |
| Regulation Section | 864.7695 | Same |
| Classification | Class II | Same |
| Intended Use | The ZYMUTEST HIA, IgG ELISA kit,is a qualitative assay intended forthe detection of heparin-dependent antibodies of the IgGisotype, in human plasma, byclinical laboratories. It is intendedfor in vitro diagnostic use. | HemosIL AcuStar HIT-IgG(PF4-H) is a qualitative, fullyautomated, chemiluminescent immunoassay (CIA)for the detection of IgG antibodies that react withPlatelet Factor 4 (PF4) when complexed to heparin.The assay is for use in human 3.2% or 3.8% citratedplasma and serum on the ACL AcuStar instrumentin a laboratory setting.The result provided by the assay should beinterpreted as either positive or negative based onthe assay cut-off (1.00 U/mL). The positive ornegative result aids in determining the risk forheparin induced thrombocytopenia (HIT) whenused in conjunction with other laboratory andclinical findings.Anti-PF4/Heparin antibodies are commonly foundin patients with HIT. For use in adult populationsuspected of HIT. Not for use in isolation toexclude HIT.HemosIL AcuStar HIT Controls are for the qualitycontrol of the HemosIL AcuStarHIT-IgG(PF4-H) assay as performed on the ACLAcuStar. |
| Differences | ||
| Sample Type | Citrated Human Plasma | Citrated Human Plasma or Serum |
| Methodology | Enzyme-linked immunosorbent assay (ELISA) | Chemiluminescent immunoassay (CIA) |
| Instrumentation | Manual | Automated ACL AcuStar instrument |
| Reagents | Microtiter plate coated with unfractionated heparin | Cartridge containing magnetic particle suspension coated with PF4 complexed to polyvinyl sulfonate (PVS) |
| Antibodies | Goat antibodies specific for human IgG | Mouse monoclonal anti-human IgG antibody |
| Conjugate | Peroxidase conjugated anti-human IgG | Isoluminol conjugated anti-human IgG |
| Cut-off | When the assay is run at 20±1°C, the results are as follows:Positive: $A450 > 0.50$ Weakly Positive: $A450 > 0.30 to < 0.50$ Negative: $A450 \le 0.30$ | Fixed clinical cut-off:Positive: $\ge 1.00$ U/mL Negative: $< 1.00$ U/mL |
| Controls | Controls included in test kit:Negative level Positive level Lyophilized Format | Controls sold separately:Low Level below the cut-off High Level above the cut-off Liquid Format |
| Calibration | Not Applicable | Lot specific Master Curve + two Calibrators (included in kit)Liquid Format |
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Performance Summary
Multi-Reagent Cartridge Lot Precision
An internal precision study was performed using three (3) different lots of HemosIL AcuStar HIT-lgG(ps4+) reagent cartridges run on an ACL AcuStar. The study used five (5) plasma samples to span the assay range; two native (unadulterated) patient samples and three prepared patient sample pools.
Each material was tested with each reagent lot in duplicate, twice a day for 22 days, for a total of 88 replicates per level per lot as summarized below:
| Reagent Lot No. 1 | |||
|---|---|---|---|
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
| Plasma Sample 1 (Pool) | 0.62 | 8.3% | 8.3% |
| Plasma Sample 2 (Pool) | 2.23 | 6.5% | 6.8% |
| Plasma Sample 3 (Native) | 21.04 | 4.8% | 5.6% |
| Plasma Sample 4 (Native) | 46.15 | 4.7% | 4.8% |
| Plasma Sample 5 (Pool) | 90.35 | 4.4% | 4.4% |
| Reagent Lot No. 2 | |||
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
| Plasma Sample 1 (Pool) | 0.52 | 8.4% | 9.2% |
| Plasma Sample 2 (Pool) | 1.98 | 7.5% | 9.3% |
| Plasma Sample 3 (Native) | 26.13 | 6.1% | 6.1% |
| Plasma Sample 4 (Native) | 54.88 | 6.9% | 7.5% |
| Plasma Sample 5 (Pool) | 111.74 | 4.1% | 7.3% |
| Reagent Lot No. 3 | |||
| Material | Mean(U/mL) | Within Run (Repeatability)% CV | Total (Within Device)% CV |
| Plasma Sample 1 (Pool) | 0.49 | 13.0% | 13.8% |
| Plasma Sample 2 (Pool) | 1.69 | 7.1% | 7.4% |
| Plasma Sample 3 (Native) | 18.40 | 7.4% | 8.1% |
| Plasma Sample 4 (Native) | 36.85 | 4.8% | 5.6% |
| Plasma Sample 5 (Pool) | 86.79 | 6.8% | 7.4% |
| Aggregated data (Reagent Lots 1, 2 and 3) | |||
| Material | Mean(U/mL) | Lot-to-Lot Variability%CV | |
| Plasma Sample 1 (Pool) | 0.54 | 11.8% | |
| Plasma Sample 2 (Pool) | 1.97 | 13.8% | |
| Plasma Sample 3 (Native) | 21.85 | 18.0% | |
| Plasma Sample 4 (Native) | 45.96 | 19.6% | |
| Plasma Sample 5 (Pool) | 96.30 | 14.0% |
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Cut-off Precision
An additional internal precision study was performed with three (3) different tots of HemoslL AcuStar (1) direct (3) plasma samples at levels near the claimed assay cut-off (1: negative sample pool; 3: unadulterated positive sample).
Each sample was analyzed with each of the three (3) reagent lots on two (2) different ACL AcuStar instruments over five (5) days for two (2) runs per day in three (3) replicates per run (N=360 per sample level) as summarized below:
| Sample | N | Mean | Within-Run(SD, %CV) | Between-Run(SD, %CV) | Between-Day(SD, %CV) | Between-Lot(SD, %CV) | Between-Instrument(SD, %CV) | Between-Operator(SD, %CV) | Total(SD, %CV) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 360 | 0.79 | 0.04; 4.7% | 0.02; 2.1% | 0.02; 2.0% | 0.07; 8.3% | 0.00; 0.0% | 0.00; 0.0% | 0.08; 10.0% |
| 2 | 360 | 1.43 | 0.06; 4.3% | 0.04; 3.0% | 0.00; 0.0% | 0.07; 4.8% | 0.00; 0.0% | 0.00; 0.0% | 0.10; 7.1% |
| 3 | 360 | 3.61 | 0.13; 3.6% | 0.14; 3.7% | 0.05; 1.5% | 0.12; 3.4% | 0.00; 0.0% | 0.00; 0.0% | 0.23; 6.4% |
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Multi-Control Lot Precision
An internal precision study was performed using three (3) different lots of HemosIL AcuStar HIT Controls (low and high) run on an ACL AcuStar, with a single lot of HemosIL AcuStar HIT-IgG(pf4-h).
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 Control Lot No. 1 | 0.58 | 4.6% | 7.0% |
| High HIT Control Lot No. 1 | 3.16 | 3.5% | 6.1% |
| Low HIT Control Lot No. 2 | 0.49 | 3.2% | 7.0% |
| High HIT Control Lot No. 2 | 2.77 | 3.4% | 5.0% |
| Low HIT Control Lot No. 3 | 0.60 | 4.1% | 6.3% |
| High HIT Control Lot No. 3 | 2.96 | 2.8% | 5.5% |
Multi-Calibrator Lot Precision
An internal precision study was performed using three (3) different lots of HemosIL AcuStar HIT-lgG(pr-4) Calibrator (kit component from 3 different assay lots) run on an ACL AcuStar, with a single lot of HemosIL AcuStar HIT-IgG(PF4-H) (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 1 Lot No. 1 | 0.92 | 3.9% | 6.3% |
| Kit Calibrator 2 Lot No. 1 | 15.37 | 3.2% | 3.9% |
| Kit Calibrator 1 Lot No. 2 | 0.94 | 2.7% | 5.4% |
| Kit Calibrator 2 Lot No. 2 | 14.85 | 2.2% | 3.1% |
| Kit Calibrator 1 Lot No. 3 | 0.90 | 2.4% | 4.0% |
| Kit Calibrator 2 Lot No. 3 | 14.90 | 3.3% | 5.0% |
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Multi-Reagent Cartridge and Control Lot 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 AcuStar instruments (one instrument per site), using three (3) different lots of HemosIL AcuStar HIT-lgGriffin reagent cartridges and HemosIL AcuStar HIT Controls (low and high). The same three (3) patient citrated plasma sample pools (2 positive and 1 negative) were also tested across the three (3) sites.
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:
| Pooled 3 Site Data: Reagent Lot No. 1 of HemosIL AcuStar HIT-IgGpf4-HJ | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | Mean | N | 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 Control | 0.64 | 90 | 0.02 | 2.5 | 0.03 | 4.7 | 0.01 | 1.7 | 0.06 | 9.2 | 0.07 | 10.7 |
| High HIT Control | 3.05 | 90 | 0.10 | 3.3 | 0.10 | 3.2 | 0.05 | 3.2 | 0.27 | 8.8 | 0.32 | 10.5 |
| Plasma Sample 1 | 0.06 | 90 | All Replicates < 1.00 U/mL | |||||||||
| Plasma Sample 2 | 3.52 | 90 | 0.17 | 4.8 | 0.09 | 2.7 | 0.07 | 1.8 | 0.16 | 4.6 | 0.26 | 7.4 |
| Plasma Sample 3 | 21.33 | 90 | 1.53 | 7.2 | 0.00 | 0.0 | 0.37 | 1.7 | 0.77 | 3.6 | 1.75 | 8.2 |
| Pooled 3 Site Data: Reagent Lot No. 2 of HemosIL AcuStar HIT-IgG(PF4-H) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | Mean(U/mL) | N | Repeatability(within-run) | Between-Run | Between-Day | Between Site | Reproducibility(Total) | ||||||
| SD | %CV | SD | %CV | SD | %CV | SD | %CV | SD | %CV | ||||
| Low HIT Control | 0.56 | 90 | 0.02 | 3.6 | 0.02 | 2.9 | 0.02 | 3.9 | 0.03 | 5.7 | 0.05 | 8.2 | |
| High HIT Control | 2.66 | 90 | 0.11 | 4.3 | 0.09 | 3.2 | 0.06 | 2.2 | 0.14 | 5.3 | 0.21 | 7.8 | |
| Plasma Sample 1 | 0.04 | 90 | All Replicates < 1.00 U/mL | ||||||||||
| Plasma Sample 2 | 3.23 | 90 | 0.15 | 4.6 | 0.14 | 4.4 | 0.10 | 3.1 | 0.24 | 7.3 | 0.33 | 10.2 | |
| Plasma Sample 3 | 20.79 | 90 | 1.41 | 6.8 | 0.42 | 2.0 | 0.50 | 2.4 | 0.88 | 4.2 | 1.79 | 8.6 |
| Pooled 3 Site Data: Reagent Lot No. 3 of HemosIL AcuStar HIT-IgG(PF4-H) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Level | Mean | N | 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 Control | 0.47 | 90 | 0.02 | 3.6 | 0.02 | 4.6 | 0.02 | 3.2 | 0.01 | 2.7 | 0.03 | 7.2 | |
| High HIT Control | 2.62 | 90 | 0.10 | 3.9 | 0.11 | 4.4 | 0.12 | 4.5 | 0.06 | 2.3 | 0.20 | 7.7 | |
| Plasma Sample 1 | 0.06 | 90 | All Replicates < 1.00 U/mL | ||||||||||
| Plasma Sample 2 | 4.47 | 90 | 0.19 | 4.3 | 0.28 | 6.3 | 0.21 | 4.7 | 0.08 | 1.8 | 0.41 | 9.2 | |
| Plasma Sample 3 | 29.64 | 90 | 1.84 | 6.2 | 1.54 | 5.2 | 1.80 | 6.1 | 0.91 | 3.1 | 3.14 | 10.6 |
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Result Interpretation
HIT-IgGpr4-n results are reported in U/mL (HemosIL AcuStar HIT-IgGpp4-n Arbitrary Units) on the ACL AcuStar instrument as follows:
| System | Results | Interpretation |
|---|---|---|
| ACL AcuStar | $≥$ 1.00 U/mL | HIT IgG Antibody positive |
| ACL AcuStar | < 1.00 U/mL | HIT IgG Antibody negative |
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 HemosIL AcuStar HIT-IgG(PF4-M) on the ACL AcuStar up to the following concentrations:
| Hemoglobin | Bilirubin | Triglycerides | HeparinLMW and UF | HAMA |
|---|---|---|---|---|
| 500 mg/dL | 18 mg/dL | 1250 mg/dL | 1 IU/mL | 1 µg/mL |
- Note: The presence of Rheumatoid Factor may produce an over estimation of the test result with the HemoslL AcuStar HIT-IgG(PF4-H) assay.
Antiphospholipid Syndrome (APS) ●
Twenty six (26) citrated plasma samples from patients diagnosed with Antiphospholipid Syndrome (APS) were tested with HemosIL AcuStar HIT-IgGps44). All 26 samples reported as negative with HemosIL AcuStar HIT-IgG(PF4-H), demonstrating that the assay is not affected by APS antibodies
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Cut-Off Determination
Eighty-seven (87) 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 (45 SRA positive and 42 SRA negative) were used to perform a Receiver Operating Characteristics (ROC) analysis. The cut-off was established as 1.00 U/mL (94.3% Agreement; 95% CI = 87.2% - 97.5%).
Reference Interval – Heparin Exposed, Non-HIT Suspected Patients
A population of 91 citrated plasma samples from heparin exposed, but non-HIT suspected patients was tested. The non-parametric 95% reference interval was calculated and the upper limit determined to be 0.75 U/mL (90% Cl: 0.46 to 2.86 U/mL).
Reference Interval – Healthy Donors
A population of 154 citrated plasma samples from apparently healthy individuals was tested. The nonparametric 95% reference interval was calculated and the upper limit determined to be 0.37 U/mL (90% Cl: 0.17 to 1.25 U/mL).
Method Comparison Definitions and Formulas
See below 2x2 contingency table with definitions and formulas.
| Reference | ||||
|---|---|---|---|---|
| + | - | |||
| Test | + | TP | FP | TP True Positives |
| - | FN | TN | TN True NegativesFP False PositivesFN False Negatives |
| PPA | Positive Percent Agreement | $PPA = \frac{TP}{TP + FN}$ | $NPA = \frac{TN}{TN + FP}$ |
|---|---|---|---|
| NPA | Negative Percent Agreement |
$$PPV ,,,= \frac{TP}{TP + FP} ,,,\quad,, NPV ,,,= \frac{TN}{TN + FN} ,,,=$$
$$\begin{array}{cc} \textbf{Total Percent Agreenment} & & \ \end{array} \ \begin{array}{c} \textbf{TP} + \textbf{TN} \ \hline \textbf{TP} + \textbf{TN} + \textbf{FP} + \textbf{FN} \ \end{array}$$
Negative Predictive Value
Positive Predictive Value
NPV
PPV
TPA
{13}------------------------------------------------
Multicenter Method Comparison
A multicenter method comparison study was performed at three (3) hospitals, comparing the performance of HemosIL AcuStar HIT-IgG(PF4-H) with the predicate device, Zymutest HIA IgG (K071255) (n=802) and with the Serotonin Release Assay (SRA) (n=790).
The samples were from patients exposed to heparin that showed HIT related symptoms.
Samples were analyzed in singlicate, with no spiked samples used in this study.
HemosIL AcuStar HIT-IgG(PF4-H) vs. Predicate Device (Zymutest HIA IgG) .
The pooled results below are based on a cut-off of 1.00 U/mL for the HemosIL AcuStar HIT-IgG(PF4-H) assay and 0.5 OD cut-off value for Zymutest HIA IgG.
| Zymutest HIA IgG Results | ||||
|---|---|---|---|---|
| + | - | Total | ||
| + | 26 | 9 | 35 | |
| HemosIL AcuStarHIT IgG(PF4-H) Results | - | 48 | 719 | 767 |
| Total | 74 | 728 | 802 |
| HemosIL AcuStar HIT IgG(PF4-H) vs. Zymutest HIA IgG | Proportion | Wilson 95% CI | |
|---|---|---|---|
| PPA (Positive Percent Agreement) | 35% (26/74) | 25% | 47% |
| NPA (Negative Percent Agreement) | 99% (719/728) | 98% | 99% |
| Total Percent Agreement | 93% (745/802) | 91% | 94% |
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HemosIL AcuStar HIT-IgG(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=12) were removed from calculations, bringing the final total to N = 790. The pooled results summarized below compare both HemosIL AcuStar HIT-lgG1p++) (cut-off of 1.00 U/mL) to the SRA test results and the Zymutest HIA IgG assay (cut-off of 0.5 OD) to the SRA test results.
- HemosIL AcuStar HIT-IgGipf4-н) Assay vs. SRA: ●
| SRA Results | HemosIL AcuStar HIT IgG(pF4-H) vs. SRA | Proportion | Wilson 95% Cl | |||||
|---|---|---|---|---|---|---|---|---|
| + | - | Total | PPV (Positive Predictive Value) | 76% (26/34) | 60% | 88% | ||
| HemosIL AcuStarHIT IgG(PF4-H) Results | + | 26 | 8 | 34 | NPV (Negative Predictive Value) | 98% (741/756) | 97% | ರಿಯ |
| - | 15 | 741 | 756 | Total Percent Agreement | 97% (767/790) | ರಿಕೆ% | 98% | |
| Total | 41 | 749 | 790 |
- Zymutest HIA IgG (Predicate) vs. SRA: ●
| SRA Results | ||||
|---|---|---|---|---|
| + | - | Total | ||
| Zymutest HIA IgGResults | + | 26 | 47 | 73 |
| - | 15 | 702 | 717 | |
| Total | 41 | 749 | 790 |
| Zymutest HIA IgG vs. SRA | Proportion | Wilson 95% CI | |
|---|---|---|---|
| PPV (Positive Predictive Value) | 36% (26/73) | 26% | 47% |
| NPV (Negative Predictive Value) | 98% (702/717) | 97% | 99% |
| Total Percent Agreement | 92% (728/790) | 90% | 94% |
- Conclusion for SRA testing: HemosIL AcuStar HIT-IgG(PF4-H) showed equivalent NPV and superior PPV performance to the predicate device when both assays were compared to the SRA method with the intended use adult population.
Conclusion:
The analytical and clinical study results demonstrate that the HemosIL AcuStar HIT-IgG(PF4-H) assay and HemosIL AcuStar HIT Controls are substantially equivalent to the predicate device, Zymutest HIA IgG (FDA cleared under K071255), 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).