vWF Ag
Device Facts
| Record ID | K220728 |
|---|---|
| Device Name | vWF Ag |
| Applicant | Siemens Healthcare Diagnostics Products GmbH |
| Product Code | GGP · Hematology |
| Decision Date | Jun 2, 2023 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 864.7290 |
| Device Class | Class 2 |
| Attributes | Pediatric |
Intended Use
In-vitro diagnostic automated assay for the quantitative determination of the von Willebrand antigen (VWF:Ag) in human plasma collected from venous blood samples in 3.2% sodium citrated tubes on the SYSMEX® CS-2500 analyzer. As an aid used in the evaluation of patients aged 4 weeks and older with suspected or confirmed von Willebrand factor disorders and intended for prescription use. Results of this test should always be interpreted in conjunction with the patient's medical history, clinical presentation and other laboratory findings.
Device Story
vWF Ag is an immunoturbidimetric assay for quantitative determination of von Willebrand factor (VWF) antigen in human citrated plasma. Kit includes latex reagent (polystyrene particles coated with rabbit anti-human VWF antibodies), diluent, and glycine buffer. Operation: sample mixed with latex reagent; VWF antigen causes particle aggregation; increase in turbidity measured photometrically at 660 nm. Performed on SYSMEX CS-2500 analyzer in clinical laboratory settings by trained personnel. Output is VWF:Ag concentration (% of norm). Results aid clinicians in diagnosing/evaluating von Willebrand disease; must be interpreted alongside medical history and other findings.
Clinical Evidence
Method comparison study (n=339) against predicate device using Passing-Bablok regression (y=1.04x - 4.60%, r=0.982). Precision/reproducibility studies (multicenter) showed total CVs of 2.03–5.96%. Reference interval study conducted on 306 healthy subjects. Pediatric study (n=47) evaluated subjects >4 weeks to <18 years. Interference testing confirmed no significant interference from endogenous substances (hemoglobin, bilirubin, lipids, rheumatoid factors) or common drugs.
Technological Characteristics
Immunoturbidimetric assay; polystyrene latex particles coated with rabbit anti-human VWF antibodies; glycine buffer; sodium azide preservative. Measuring interval 4-300% of norm. Analyzed on SYSMEX CS-2500 (660 nm). Traceable to WHO 6th IS (07/316).
Indications for Use
Indicated for patients aged 4 weeks and older with suspected or confirmed von Willebrand factor disorders. Used as an aid in clinical evaluation.
Predicate Devices
- Sta - Liatest vWF Test Kit (K962675)
Related Devices
- K992704 — IL TEST VON WILLEBRAND FACTOR · Instrumentation Laboratory CO · Nov 1, 1999
- K040843 — HEMOSIL VON WILLEBRAND ACTIVITY · Instrumentation Laboratory CO · Apr 30, 2004
- K962675 — STA - LIATEST VWF TEST KIT · American Bioproducts Co. · Oct 25, 1996
Submission Summary (Full Text)
{0}
510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY
I Background Information:
A 510(k) Number
K220728
B Applicant
Siemens Healthcare Diagnostics Products GmbH
C Proprietary and Established Names
vWF Ag
D Regulatory Information
| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| GGP | Class II | 21 CFR 864.7290 - Factor Deficiency Test | HE - Hematology |
II Submission/Device Overview:
A Purpose for Submission:
Clearance of a new device
B Measurand:
VWF:Ag
C Type of Test:
Immunoturbidimetric assay for the quantitative, WHO-standardized determination of von Willebrand factor (VWF) antigen concentration.
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 1 of 14
{1}
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 2 of 14
# III Intended Use/Indications for Use:
## A Intended Use(s):
See Indications for Use below.
## B Indication(s) for Use:
In-vitro diagnostic automated assay for the quantitative determination of the von Willebrand antigen (VWF:Ag) in human plasma collected from venous blood samples in 3.2% sodium citrated tubes on the SYSMEX CS-2500 analyzer.
As an aid used in the evaluation of patients aged 4 weeks and older with suspected or confirmed von Willebrand factor disorders and intended for prescription use.
Results of this test should always be interpreted in conjunction with the patient’s medical history, clinical presentation and other laboratory findings.
## C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only
## D Special Instrument Requirements:
SYSMEX Automated Blood Coagulation Analyzer CS-2500 (K172286)
# IV Device/System Characteristics:
## A Device Description:
**Assay and Reagents**
The vWF Ag is an immunoturbidimetric assay for the quantitative determination of von Willebrand factor (VWF) antigen levels.
The vWF Ag kit consists of a ready to use Latex Reagent (4 x 2 mL vials / kit) which is a suspension of small polystyrene particles (latex) coated with rabbit anti-human VWF antibodies. The Reagent Diluent (4 x 4 mL vials / kit) is provided within the kit which is a solution containing glycine. The Reagent Diluent is intended for dilution of the Latex Reagent. The vWF Ag kit is completed by the Buffer (4 x 5 mL vials / kit) which is a glycine buffer. All components contain sodium azide (>1 g/L) as a preservative.
## B Principle of Operation:
The small polystyrene particles to which rabbit anti-human vWF antibodies have been attached by covalent bonding are aggregated when mixing with samples containing von Willebrand antigen. This aggregation is then detected turbidimetrically by the Sysmex CS-2500 analyzer, via the increase in turbidity, which is proportional to the antigen level present in the test sample.
# V Substantial Equivalence Information:
## A Predicate Device Name(s):
Sta - Liatest vWF Test Kit
{2}
B Predicate 510(k) Number(s):
K962675
C Comparison with Predicate(s):
| Device & Predicate Device(s): | K220728 | K962675 |
| --- | --- | --- |
| Device Trade Name | vWF Ag | STA-Liatest VWF:Ag |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | In-vitro diagnostic automated assay for the quantitative determination of the von Willebrand antigen (VWF:Ag) in human plasma collected from venous blood samples in 3.2% sodium citrated tubes on the SYSMEX CS-2500 analyzer. As an aid used in the evaluation of patients with suspected or confirmed von Willebrand factor disorders and intended for prescription use. Results of this test should always be interpreted in conjunction with the patient's medical history, clinical presentation and other laboratory findings. | The STA – Liatest VWF:Ag kit is intended for use with STA-R® and STA Compact, for the quantitative determination of von Willebrand factor antigen (VWF:Ag) in plasma by the immuno-turbidimetric method. |
| Measurand | VWF:Ag | Same |
| Unit | % of norm (100% of norm equals 1.00 IU) | % (100% equals 1.00 IU) |
| Sample Type | Citrated human plasma from venous blood
Citrated platelet poor human plasma | Same |
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 3 of 14
{3}
| | | |
| --- | --- | --- |
| Shelf Life | 18 months at 2 – 8°C | Same |
| General Device Characteristic Differences | | |
| Classification Product Code | GGP | GJT |
| Measuring Interval | 4 – 300% of norm | 3 – 420% |
| Control Level | 3 Control levels (sold separately from the assay):
Control Plasma N (K042333, normal range)
Control Plasma P and Control Plasma P 1:6 diluted (K042209, pathological range) | 2 Control levels (sold separately from the assay):
STA-Liatest Control N (normal range)
STA-Liatest Control P (pathological range) |
| Test Principle analyzer measuring principle (wavelength) | Immuno-turbidimetry (660 nm) | Immuno-turbidimetry (540 nm) |
| Test Principle (biochemical principle of reagent) | Small polystyrene particles to which specific antibodies have been attached by covalent bonding are aggregated when mixing with samples containing von Willebrand antigen. This aggregation is then detected turbidimetrically via the increase in turbidity, which is proportional to the antigen level present in the test sample. | This assay is based on the change in turbidity of a microparticle suspension that is measured by photometry. A suspension of latex microparticles, coated by covalent bonding with antibodies specific for VWF, is mixed with the test plasma whose VWF antigen level is to be assayed. An antigen-antibody reaction takes place, leading to an agglutination of the latex microparticles which induces an increase in turbidity of the reaction medium. This increase in turbidity is reflected by |
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 4 of 14
{4}
| | | an increase in absorbance, the latter being measured photometrically. The increase in absorbance is a function of the VWF level present in the test sample. |
| --- | --- | --- |
| Reagents | vWF Ag Buffer: - Glycine buffer - Sodium azide (< 1 g/L)
vWF Ag Latex Reagent: - Suspension of small polystyrene particles coated with rabbit anti-human VWF antibodies. - Sodium azide (< 1 g/L)
vWF Ag Diluent for Latex Reagent: - Solution containing glycine intended for dilution of the Latex Reagent - Sodium azide (< 1 g/L) | Reagent 1: - Glycine buffer - Sodium azide (< 1 g/L)
Reagent 2: - Suspension of microlatex particles coated with rabbit antihuman VWF antibodies - Sodium azide (< 1 g/L)
Reagent 3: - Solution containing glycine for dilution of Latex reagent (Reagent 2) - Sodium azide (< 1 g/L) |
| Buffer | Dade Owren’s Veronal Buffer | STA - Owren-Koller |
| Stability Once Opened | 4 weeks at 2 – 8°C | Not specified in package insert |
| On Board Stability | In original vials the vWF Ag Reagent and vWF Ag Buffer may be left on board the instrument for 100 hours. The reagent vials can stay continuously on board or be removed | With STA - mini Reducer and perforated cap in place the stability of Reagent 2 after dilution is 15 days on STA-R and STA Compact. |
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 5 of 14
{5}
VI Standards/Guidance Documents Referenced:
CLSI EP17-A2: Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures; Approved Guideline – Second Edition
CLSI EP25-A: Evaluation of Stability of In Vitro Diagnostic Reagents; Approved Guideline
CLSI EP06-A: Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; Approved Guideline
CLSI EP07: Interference Testing in Clinical Chemistry, 3rd Edition
CLSI EP37: Supplemental Tables for Interference Testing in Clinical Chemistry, 1st Edition
CLSI EP28-A3c: Defining, Establishing, and Verifying Reference Intervals in Clinical Laboratory; Approved Guideline – Third Edition
CLSI EP05-A3: Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline – Third Edition
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 6 of 14
{6}
VII Performance Characteristics (if/when applicable):
A Analytical Performance:
1. Precision/Reproducibility:
Repeatability (Single site): A single-site (internal) precision study was performed for the performance evaluation of vWF Ag. The study was performed on 20 days with two runs per day and two replicates (20 x 2 x 2) of each sample per run on one SYSMEX CS-2500 analyzer. One reagent lot was investigated in combination with three calibrator lots, in addition, one calibrator lot was investigated in combination with three reagent lots for a total of 240 determinations (i.e., 80 determinations per reagent or calibrator lot). Three plasma pools (PP1–3) as well as three control materials (CPN, CPP, CPP 1:6 dilution) were investigated as test samples. The samples were chosen to cover the respective measuring interval of vWF Ag (4 to 300% of norm) and the medical decision levels (30% of norm, 50% of norm). All measurands met the predefined acceptance criteria. The results for within-run, between-lot and total imprecision are presented in the summary tables below.
Table 1. Evaluation of 3x20x2x2 Precision Study at Single Site – investigation of reagent variability.
| Sample | N | Mean (% of norm) | | | | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Within-Run | | Between-Run | | Between-Day | | Between-Reagent Lot | | Within-Laboratory | |
| | | | SD | CV% | SD | CV% | SD | CV% | SD | CV% | SD | CV% |
| CPP 1:6 | 240 | 6.31 | 0.20 | 3.13 | 0.17 | 2.67 | 0.00 | 0.00 | 0.05 | 0.87 | 0.27 | 4.20 |
| PP1 | 240 | 25.26 | 0.77 | 3.07 | 0.46 | 1.82 | 0.22 | 0.87 | 0.71 | 2.81 | 1.17 | 4.62 |
| CPP | 240 | 39.74 | 2.65 | 6.68 | 0.00 | 0.00 | 0.75 | 1.88 | 0.99 | 2.48 | 2.93 | 7.37 |
| PP2 | 240 | 52.26 | 0.69 | 1.32 | 0.47 | 0.89 | 0.46 | 0.88 | 0.92 | 1.76 | 1.32 | 2.53 |
| CPN | 240 | 135.46 | 2.53 | 1.86 | 1.44 | 1.06 | 1.74 | 1.29 | 2.67 | 1.97 | 4.32 | 3.19 |
| PP3 | 240 | 285.79 | 4.98 | 1.74 | 4.98 | 1.74 | 1.85 | 0.65 | 9.19 | 3.22 | 11.73 | 4.10 |
Table 2. Evaluation of 3x20x2x2 Precision Study at Single Site – investigation of calibrator variability.
| Sample | N | Mean (% of norm) | | | | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Within-Run | | Between-Run | | Between-Day | | Between-Calibrator Lot | | Within-Laboratory | |
| | | | SD | CV% | SD | CV% | SD | CV% | SD | CV% | SD | CV% |
| CPP 1:6 | 240 | 6.44 | 0.15 | 2.32 | 0.19 | 2.94 | 0.00 | 0.00 | 0.30 | 4.73 | 0.39 | 6.03 |
| PP1 | 240 | 25.48 | 0.33 | 1.31 | 0.24 | 0.93 | 0.00 | 0.00 | 0.80 | 3.14 | 0.90 | 3.53 |
| CPP | 240 | 38.02 | 2.30 | 6.06 | 0.00 | 0.00 | 0.59 | 1.55 | 1.09 | 2.87 | 2.62 | 6.88 |
| PP2 | 240 | 51.38 | 0.57 | 1.10 | 0.44 | 0.85 | 0.61 | 1.18 | 0.92 | 1.79 | 1.31 | 2.55 |
| CPN | 240 | 133.00 | 1.89 | 1.42 | 1.63 | 1.23 | 2.01 | 1.51 | 1.45 | 1.09 | 3.52 | 2.64 |
| PP3 | 240 | 276.99 | 4.78 | 1.73 | 4.43 | 1.60 | 2.69 | 0.97 | 5.72 | 2.07 | 9.08 | 3.28 |
Precision study (Single site, for Instrument/Operator Variability): This study was conducted to evaluate instrument/operator variability at one internal site. This study was conducted on five days, with two runs per day and four replicates of each sample per run (5 x 2 x 4) on three SYSMEX CS-2500 analyzers for a total of 120 determinations (i.e., 40 determinations
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 7 of 14
{7}
per instrument/operator combination). The study investigated one reagent/calibrator lot combination on all three SYSMEX CS-2500 analyzers.
Three plasma pools (PP1-3) as well as three control materials (CPN, CPP, CPP 1:6 dilution) were investigated as test samples. The samples were chosen to cover the respective measuring interval of vWF Ag (4 to 300% of norm) and the medical decision levels (30% of norm, 50% of norm). All measurands met the predefined acceptance criteria The results for within-run, between-instrument/operator and total imprecision are provided in the summary table below.
Table 3. Evaluation of 3x5x2x4 precision study for vWF Ag on the SYSMEX CS-2500 analyzer at single site; instrument/operator combined.
| Sample | N | Mean (% of norm) | | | | | | | | | | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Within-Run | | Between-Run | | Between-Day | | Within-Site | | Between-Site | | Within-Laboratory | |
| | | | SD | CV% | SD | CV% | SD | CV% | SD | CV% | SD | CV% | SD | CV% |
| CPP 1:6 | 90 | 7.49 | 0.21 | 2.82 | 0.11 | 1.42 | 0.00 | 0.00 | 0.24 | 3.16 | 0.10 | 1.29 | 0.26 | 3.41 |
| PP1 | 90 | 24.34 | 0.31 | 1.27 | 0.16 | 0.65 | 0.00 | 0.00 | 0.35 | 1.42 | 0.61 | 2.52 | 0.70 | 2.90 |
| CPP | 90 | 42.83 | 1.84 | 4.28 | 0.00 | 0.00 | 0.70 | 1.65 | 1.97 | 4.59 | 1.63 | 3.79 | 2.55 | 5.96 |
| PP2 | 90 | 49.04 | 0.73 | 1.48 | 0.43 | 0.87 | 0.48 | 0.97 | 0.97 | 1.97 | 1.19 | 2.43 | 1.53 | 3.13 |
| CPN | 90 | 129.91 | 3.03 | 2.33 | 0.23 | 0.18 | 1.92 | 1.48 | 3.59 | 2.77 | 1.06 | 0.81 | 3.75 | 2.88 |
| PP3 | 90 | 259.77 | 2.95 | 1.14 | 2.60 | 1.00 | 2.73 | 1.05 | 4.78 | 1.84 | 2.23 | 0.86 | 5.28 | 2.03 |
Reproducibility (multi-site): The external reproducibility study was carried out at three external sites, on five days, with two runs per day and three replicates of each sample per run $(3 \times 5 \times 2 \times 3)$ for a total of 90 determinations (i.e., 30 determinations per site). All external sites performed the reproducibility study with the same reagent/calibrator lot combination. Three plasma pools (PP1-3) as well as three control materials (CPN, CPP, CPP 1:6 dilution) were investigated as test samples. The samples were chosen to cover the respective measuring interval of vWF Ag (4 to $300\%$ of norm) and the medical decision levels $(30\%$ of norm, $50\%$ of norm). All measurands met the predefined acceptance criteria. The results for within-run, between-laboratory and total imprecision are provided in the summary table below.
Table 4. Evaluation of 3x5x2x3 Reproducibility study for vWF Ag on the SYSMEX CS-2500 analyzer; all three external (US) sites combined.
| Sample | N | Mean (% of norm) | Within-Run | | Between-Run | | Between-Day | | Between-Instrument/Operator | | Total | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | SD | CV% | SD | CV% | SD | CV% | SD | CV% | SD | CV% |
| CPP 1:6 | 120 | 6.51 | 0.10 | 1.51 | 0.06 | 0.87 | 0.02 | 0.33 | 0.00 | 0.00 | 0.12 | 1.77 |
| PP1 | 120 | 22.65 | 0.35 | 1.55 | 0.04 | 0.19 | 0.21 | 0.92 | 0.59 | 2.62 | 0.72 | 3.19 |
| CPP | 120 | 37.22 | 1.18 | 3.16 | 0.00 | 0.00 | 0.45 | 1.20 | 1.52 | 4.08 | 1.97 | 5.30 |
| PP2 | 120 | 46.24 | 0.78 | 1.70 | 0.39 | 0.83 | 0.70 | 1.52 | 0.98 | 2.12 | 1.49 | 3.22 |
| CPN | 120 | 112.78 | 1.65 | 1.47 | 0.78 | 0.70 | 1.75 | 1.55 | 0.00 | 0.00 | 2.53 | 2.24 |
| PP3 | 120 | 265.54 | 6.91 | 2.60 | 2.50 | 0.94 | 4.14 | 1.56 | 7.50 | 2.82 | 11.29 | 4.25 |
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 8 of 14
{8}
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 9 of 14
2. Linearity:
The linearity study was performed following the CLSI EP06 2nd Ed guideline, on one day, using three SYMEX CS-2500 analyzers with three lots of vWF Ag reagent (one lot per analyzer), and four replicates of each sample (dilution). The dilution series was prepared by mixing a high concentration sample pool (high pool) with a low concentration sample pool (low pool). The high pool was prepared by spiking a normal plasma pool with a VWF concentrate. The VWF deficient plasma was internally produced by immunoaffinity chromatography.
Samples with 12 different dilutions were evaluated in the linearity study. Determination of linearity was performed using weighted linear regression using no intercept in the model. The deviation between the mean measured value and the predicted value of the linear regression was calculated for each sample concentration. The calculated deviations were then compared to the acceptance criteria and the linear range was defined accordingly. The results support the linearity range of 4 to 300% of norm on the SYSMEX CS-2500 analyzer.
3. Analytical Specificity/Interference:
Interference studies were conducted based on the CLSI EP07 3rd edition, and CLSI EP37 1st edition guidelines.
Endogenous Interference Study:
Dose-response experiments were carried out to determine the degree of interference as a function of the interferent concentration for endogenous interferents hemoglobin, unconjugated bilirubin, conjugated bilirubin, lipids, and rheumatoid factors. The interference study was carried out with one SYSMEX CS-2500 analyzer and one vWF Ag lot. Each VWF antigen level was investigated with five different test samples. Each sample was tested in triplicate on one day and with one lot of Standard Human Plasma (SHP) as calibrator. For testing the interference by human anti-mouse antibodies (HAMAs), 12 test samples (HAMA-positive) and 12 control samples (HAMA-positive) were used as per CLSI 1/LA30-A. Similarly, for the potential interference by lupus anticoagulant, 12 test samples (Lupus-positive) and 12 control samples (Lupus-negative) were used. None of the listed endogenous substances in the following table were found to cause interference up to the indicated concentrations:
| Interferent | No interference up to: |
| --- | --- |
| Hemoglobin | 712 mg/dL |
| Bilirubin (unconjugated) | 30 mg/dL |
| Bilirubin (conjugated) | 100 mg/dL |
| Lipids* | 549 mg/dL |
| Rheumatoid Factors | 23 IU/mL |
| HAMA | 499 ng/mL |
| Lupus Anticoagulant | dRVVT ratio = 2.49 |
Exogenous Interference Study:
Interference study on potentially exogenous interfering substances (drug panel) were conducted to evaluate the potential interference of over-the-counter drugs and prescription
{9}
drugs for the vWF Ag assay on the SYSMEX CS-2500 analyzer. The interference study (drug panel) was carried out with one SYSMEX CS-2500 analyzer and one vWF Ag lot. The maximum concentration of each interferent was determined per CLSI EP37 guideline. None of the substances in the following table (exogenous substances/drug panel) were found to lead to clinically significant interference.
| Interferent | No interference up to: |
| --- | --- |
| Acetaminophen (Paracetamol) | 156 μg/mL |
| Acetyl salicylic acid | 30 μg/mL |
| Amitriptyline hydrochloride | 543 ng/ml |
| Atorvastatin calcium salt trihydrate | 812 ng/mL |
| Budesonide | 6.3 ng/mL |
| Carbimazol | 3.6 μg/ml |
| Ciprofloxacin | 12 μg/mL |
| Cisplatin | 33 μg/mL |
| Citalopram hydrobromide | 6.79 μg/mL |
| Clopidogrel hydrogensulfate | 24 ng/mL |
| Diclofenac sodium salt | 26 μg/mL |
| Emicizumab | 300 μg/mL |
| Estradiol | 7.5 pg/mL |
| Ibuprofen sodium salt | 240 μg/mL |
| Lenalidomide | 2.13 μg/mL |
| Lisinopril dihydrate | 268 ng/mL |
| L-Thyroxin | 180 ng/mL |
| Metformin Hydrochloride | 15.4 μg/mL |
| Pantoprazole sodium sesquihydrate | 34 μg/mL |
| Progesterone | 540 ng/mL |
| Ramipril | 156 ng/mL |
| RFVIIa: NovoSeven® (Eptacog alfa activated) | 4.5 μg/mL |
| RFVIII: ELOCTA® (Efmroctocog alfa) | 1.875 IU/mL |
| RFVIII: Esperoct® (Turoctocog alfa pegol) | 1.875 IU/mL |
| Tetracycline | 24 μg/mL |
| Theophylline | 60 μg/mL |
| Thiouracil (2-Thiouracil) | 15.9 μg/mL |
| Ticagrelor | 108 μg/mL |
| Tranexamic Acid | 162.9 μg/mL |
| Valproic Acid | 318 μg/mL |
| Valsartan | 11.7 μg/mL |
4. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
a. Sample Stability Study
Sample stability study was performed to investigate the sample stability characteristics of the proposed device under defined storage conditions with 23 to 25 samples covering the measuring interval of vWF Ag (4 to 300% of norm) at one external study site and one internal study site. 3 out 25 samples belong to ≤ 20% of vWF Ag norm, among
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 10 of 14
{10}
which 2 samples were contrived. The remaining 20 samples belong to >20% of vWF Ag norm. All sample measurements at storage condition of the sample stability study, except for the measurement after storage at ≤ 70°C, were performed with one reagent lot vWF Ag, one lot calibrator (SHP) as four single determinations on one SYSMEX CS-2500 analyzer at the respective study site. Evaluation of sample stability at ≤ -70°C were performed with another reagent lot vWF Ag, and another calibrator lot (SHP) on one SYSMEX CS-2500 analyzer. One calibration curve was established (for each reagent / calibrator lot) and used for the entire sample stability at each study site. The data support a sample stability claim of 4 hours at 15 to 25°C (primary and secondary cups), 4 hours at 15 to 25°C (once frozen), 3 months at ≤ -20°C, 6 months stability at ≤ -70°C.
b. Traceability Study
The objective of this study is to investigate the traceability of the assigned value of SHP to the WHO 6th International Standard (IS) Factor VIII / Von Willebrand Factor (NIBSC code 07/316). The study was carried out with three different reagent lots of the vWF Ag assay, on one SYSMEX CS-2500 analyzer and three SHP lots. Four vials of the WHO 6th International Standard for Factor VIII / Von Willebrand Factor were investigated in single determination on one day and with one trained operator. With each vWF Ag reagent lot three calibration curves were established with the three SHP lots. The accuracy of the calibration curves was assessed by running the appropriate control materials, Control Plasma N (normal) and Control Plasma P (pathologic), before and after the measurements. The predetermined acceptance criterion was fulfilled, confirming that the candidate vWF assay is traceable to WHO 6th International Standard Factor VIII / Von Willebrand Factor (07/316).
c. Shelf Life Stability of Reagent
The shelf life stability study for vWF Ag was performed in accordance with the CLSI EP25-A, using an isochronous design, where the product was placed under the test storage conditions (2 to 8°C) at the start of the study and then withdrawn for testing at different time points (0, 3, 6, 9, 12, 15, and 18 months) using three lots of vWF Ag vials. Four plasma pools as well as three control materials were investigated as test samples. The samples were chosen to cover the respective measuring interval of vWF Ag (4 to 300% of norm). The results support a reagent shelf-life stability claim of 18 months when stored at 2 to 8°C.
d. Shelf Life Stability of Calibrator
The shelf life stability study for SHP for use as calibrator for vWF Ag was performed according to the CLSI EP25-A. The study was conducted by testing three SHP lots at the following time-points (0, 3, 6, 9, 12, 15, 18, 21, 24 and 25 months). The SHP is placed under the storage conditions (2 to 8°C) at the start of the study and then withdrawn for testing at different time points throughout the study duration. Four to 8 replicates per sample were measured at each time point. The results support a shelf-life stability claim of 24 months for SHP, when stored at 2 to 8°C.
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 11 of 14
{11}
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 12 of 14
# 5. Detection Limit:
The detection limits of the vWF Ag assay – limit of blank (LoB), limit of detection (LoD), limit of quantitation (LoQ) were determined following the CLSI EP17-A2 guideline.
The LoB study was performed with five independent analyte-free plasma samples internally prepared by immunoaffinity chromatography. The study was carried out with one SYSMEX CS-2500 analyzer, three different reagent lots, one calibrator lot, five analyte-free samples, one single determination of four individual aliquots of each sample on three days, resulting in 60 measurements per reagent lot, and 180 measurements overall. The results determine the LoB for the vWF Ag as 1.07% of norm.
The LoD study was performed with five independent low-analyte samples. The samples were prepared by dilution of a normal plasma sample, to levels within the calibrated range but below 4% of norm with VWF deficient plasmas. The study was carried out with one SYSMEX CS-2500 analyzer, three different reagent lots, one calibrator lot, five analyte-free samples, one single determination of four individual aliquots of each sample on three days, resulting in 60 measurements per reagent lot, and 180 measurements overall. The results determine the LoD for the vWF Ag as 1.81% of norm.
This LoQ study was with five independent low-analyte samples, by dilution of five 5 different normal plasma samples, with five 5 different VWF:Ag deficient plasma pools resulting in low-analyte samples with 3 to 4% of norm VWF antigen (assigned value of the LoQ samples). The study was carried out with one SYSMEX CS-2500 analyzer, three different reagent lots, one calibrator lot, five low analyte samples, single determination of four individual aliquots of each sample on three days, resulting in 60 measurements per reagent lot, and 180 measurements overall. The results determine the LoQ for the vWF Ag as 3.12% of norm.
# 6. Assay Cut-Off:
Not applicable.
# B Comparison Studies:
1. Method Comparison with Predicate Device:
Method comparison studies was performed at three clinical study sites to compare the performance of the vWF Ag assay on the SYSMEX CS-2500 analyzer with the STA - Liatest VWF:Ag assay (K962675) on the STA R Max analyzer (K151867). A total of 370 samples were evaluated from three sites. To support the intended use population, patient samples with various demographics (i.e. age, gender, race/ethnicity), were included in the study. The patient cohort included patients previously diagnosed with von Willebrand disease (VWD) (VWD type 1, VWD type 2 (type 2A, 2B, 2M and 2N), VWD type 3, and patients with acquired VWD), patients with hemophilia A, patient with platelet dysfunction and patients without final VWD related diagnosis at the time of enrollment. All samples were collected in 3.2% sodium citrate anticoagulant and tested in singlet with both methods (subject and comparator). Patient sample demographics included 235 females and 135 males, ≥ 4 weeks of age. Out of the 370 samples, 339 patients demonstrated VWF:Ag values inside the
{12}
measuring interval of the proposed and predicate device and are thus included in the statistical evaluation. The predefined acceptance criteria for Passing-Bablok regression analysis, predicted bias at medical decision points, and Pearson correlation coefficient were achieved.
| Study Site | n | Sample Range | Slope (95%CI) | Intercept (% of norm) (95% CI) | Pearson correlation coefficient (r) |
| --- | --- | --- | --- | --- | --- |
| All sites combined | 339 | 5.4–289.9% of norm | 1.036 (1.018, 1.055) | -4.602 (-6.016, -3.509) | 0.982 |
2. Matrix Comparison: Not applicable
C Clinical Studies:
1. Clinical Sensitivity: Not applicable
2. Clinical Specificity: Not applicable
3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable): Not applicable
D Clinical Cut-Off: Not applicable
E Expected Values/Reference Range:
Reference interval studies for the two subgroups investigated (blood group O and non-O) were conducted at three clinical sites. Citrated plasma samples were obtained from 306 apparently healthy individuals (147 blood group O and 159 blood group non-O) ≥ 18 years of age. At each site the plasma samples were measured with one vWF Ag lot, one SHP lot, on one SYSMEX CS-2500 analyzer, in single determination. Results from all sites were pooled and all reference intervals were established by calculating two-sided 95% central interval (2.5th /97.5th percentiles) as the 97.5th percentile was found within the measuring interval. The results for the generic VWF activity reference interval (pooled data of the multicenter study), ABO blood group-specific reference intervals are summarized in the table below.
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 13 of 14
{13}
Reference Intervals Summary
| ABO Blood Group | N | 2.5th Percentile
(95% confidence interval) | 97.5th Percentile
(95% confidence interval) |
| --- | --- | --- | --- |
| ABO blood groups combined | 306 | 50.6%
(45.2%, 58.9%) | 271.2%
(222.8%, 298.3%) |
| Blood group O | 147 | 46.6%
(32.6%, 54.1%) | 202.1%
(153.8%, 295.6%) |
| Blood group non-O (groups A, B, AB) | 159 | 54.3%
(50.1%, 71.8%) | 293.6%
(245.7%, *) |
*The upper 95% confidence limit for the 97.5th percentile cannot be stated for this subgroup, because corresponding to the sample size of n=159, the highest observation represents the upper limit of the 95% confidence range for the 97.5th percentile. The highest observation in this subgroup was above the measuring interval vWF Ag (>300% of norm).
VIII Proposed Labeling:
The labeling supports the finding of substantial equivalence for this device.
IX Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
K220728 - Page 14 of 14
