VIDAS® FT4 is an automated quantitative enzyme immunoassay for use on the instruments of the VIDAS® family, for the determination of free thyroxine (FT4) in human serum or plasma (lithium heparin), using the ELFA technique (Enzyme Linked Fluorescent Assay). Measurement of Free Thyroxin is intended for use as an aid in the diagnosis and treatment monitoring of thyroid disorders.

Device Description

VIDAS® FT4 is an automated quantitative enzyme immunoassay for use on the instruments of the VIDAS® family, for the determination of free thyroxine (FT4) in human serum or plasma (lithium heparin), using the ELFA technique (Enzyme Linked Fluorescent Assay). Measurement of free thyroxine is intended for use as an aid in the diagnosis and treatment monitoring of thyroid disorders.

The assay principle combines a one-step enzyme immunoassay competition method with a final fluorescent detection (ELFA).

The Solid Phase Receptacle (SPR®) serves as the solid phase as well as the pipetting device for the assay. Reagents for the assay are ready-to-use and pre-dispensed in the sealed reagent strips. All of the assay steps are performed automatically by the instrument. The reaction medium is cvcled in and out of the SPR several times.

The sample is collected and transferred into the well containing an alkaline phosphataselabeled anti-T4 antibody (conjugate). The antiqen present in the sample and the T4 antigen coated on the interior of the SPR compete for the available sites on the specific anti-T4 antibody conjugated to alkaline phosphatase.

During the final detection step, the substrate (4-Methyl-umbellifery) phosphate) is cvcled in and out of the SPR. The conjugate enzyme catalyzes the hydrolysis of this substrate into a fluorescent product (4-Methyl-umbelliferone) the fluorescence of which is measured at 450 nm. The intensity of the fluorescence is inversely proportional to the concentration of free thyroxine present in the sample. At the end of the assay, results are automatically calculated by the instrument in relation to the calibration curve stored in memory, and then printed out.

AI/ML Overview

The provided text describes the performance of the VIDAS® FT4 device, an automated quantitative enzyme immunoassay for free thyroxine. However, it does not explicitly state "acceptance criteria" as a separate, pre-defined set of thresholds. Instead, it presents various performance study results (e.g., precision, linearity, correlation, analytical sensitivity, specificity) which implicitly demonstrate that the device meets the necessary performance expectations for its intended use and for demonstrating substantial equivalence to its predicate device.

1. Table of Acceptance Criteria and Reported Device Performance

As explicit acceptance criteria are not tabulated in the document, I will infer the performance metrics considered crucial from the studies presented. For "Acceptance Criteria," I will describe the objective assessed in each study.

Performance Metric (Implied Acceptance Criteria)	Reported Device Performance (VIDAS® FT4)
Analytical Specificity
Interference with Bilirubin	No significant interference up to 22.5 mg/dL.
Interference with Lipids	No significant interference up to 750 mg/dL.
Interference with Hemoglobin	No significant interference up to 500 mg/dL.
Interference with HAMA	No significant interference up to 0.2 mg/dL.
Interference with Albumin	No significant interference up to 6300 mg/dL.
Interference with Drugs	No significant interference observed up to specified concentrations for various drugs (e.g., Acetylsalicylic Acid: 32.61 mg/dL, Amiodarone: 0.58 mg/dL, Carbamazepine: 1.5 mg/dL, etc.).
Cross-reactivity (Structurally related molecules)	No significant interference observed at specified concentrations for 3,5-diiodotyrosine (16.770 µg/dL, 0.00095% cross-reactivity), 3,5-diodothyronine (27.310 µg/dL, 0.00040% cross-reactivity), and L-triiodothyronine (0.678 µg/dL, 0.02655% cross-reactivity).
Analytical Sensitivity
Limit of Blank (LoB)	0.02 ng/dL
Limit of Detection (LoD)	0.07 ng/dL
Limit of Quantitation (LoQ)	0.13 ng/dL (defined as lowest analyte concentration reproducibly measured with a within-laboratory precision CV of ≤ 20%).
Measurement Range	0.13 ng/dL to 6.61 ng/dL.
Linearity	Linear over the whole measurement range (0.13 ng/dL to 6.61 ng/dL) on both VIDAS® and miniVIDAS® instruments.
Matrix Comparison	High correlation coefficients (r > 0.99) and regression analyses (slopes close to 1, intercepts close to 0) indicating equivalence between different blood collection tube types (plastic tube with clot activator, plastic tube with separation gel, plastic tube with lithium heparin, plastic tube with lithium heparin and separation gel) and the reference silicone-coated glass tube. E.g., Plastic tube with clot activator: Y = 0.98X + 0.01, r = 0.999.
Precision	VIDAS® instruments: Repeatability CVs ranged from 2.3% to 6.3%. Reproducibility CVs ranged from 5.1% to 13.4%. miniVIDAS® instruments: Repeatability CVs ranged from 2.0% to 11.2%. Reproducibility CVs ranged from 2.8% to 15.4%.
Correlation	VIDAS®: Slope 1.03 (0.99-1.06 CI), Intercept -0.02 (-0.13-0.05 CI), Correlation coefficient (r) 0.988 (0.980-0.993 CI) when compared to a commercially available Free T4 EIA. miniVIDAS®: Slope 1.04 (1.00-1.08 CI), Intercept 0.01 (-0.06-0.12 CI), Correlation coefficient (r) 0.987 (0.977-0.992 CI) when compared to a commercially available Free T4 EIA.
Reference Range / Expected Values	Established reference interval: 0.77 - 1.51 ng/dL (2.5th and 97.5th percentiles). 90% CI for lower limit: 0.70 - 0.79 ng/dL. 90% CI for upper limit: 1.41 - 1.59 ng/dL. This was determined from a population of 544 healthy subjects.

2. Sample Sizes Used for the Test Set and Data Provenance

Due to the nature of an in vitro diagnostic (IVD) device, the "test set" is not a singular set of patient cases for a diagnostic decision, but rather refers to various samples used across different analytical and clinical performance studies. The data provenance is generally not explicitly stated as "country of origin" for these types of analytical validation studies but implies laboratory testing within the manufacturer's R&D facilities or contracted labs, primarily related to the device itself.

Analytical Specificity (Interferences): For common interferences (bilirubin, lipids, hemoglobin, HAMA, albumin), the study involved serum samples at FT4 analyte levels close to the lower and higher limits of the euthyroid range. The number of samples for each interference type is not specified beyond "samples." For drugs, the number of samples is not specified. For structurally related molecules, the study involved tested FT4 concentrations of approximately 1.2 ng/dL and 2.5 ng/dL, but the number of samples is not explicitly given. This data is likely generated prospectively in a laboratory setting.
Analytical Sensitivity (LoB, LoD, LoQ):
- LoB: One blank sample, N=60 measures per lot on each instrument (2 lots on one VIDAS®, 1 lot on one miniVIDAS®).
- LoD: Low concentration samples (number not specified for VIDAS®, 4 samples for miniVIDAS®), N=150 measures per lot on VIDAS®, N=100 measures per lot on miniVIDAS®.
- LoQ: 9 low concentration samples, N=40 measures per sample and per lot on each instrument (2 lots on one VIDAS®, 1 lot on one miniVIDAS®).
- This data is prospectively generated in a laboratory setting.
Linearity: The study was conducted on the VIDAS® and miniVIDAS® instruments. The number of samples or points tested is not explicitly stated. This data is prospectively generated in a laboratory setting.
Matrix Comparison: 31 sample sets (each set from one donor during one draw, consisting of a reference tube type and four different blood collection tubes). Samples ranged from 0.13 ng/dL to 6.45 ng/dL. This data is prospectively generated.
Precision: Panel members covering the measuring range were tested. 6 samples for VIDAS® instruments, and 5 samples for miniVIDAS® instruments. Total N=240 measures for each sample/instrument type. This data is prospectively generated in a laboratory setting.
Correlation: 54 samples were included in the study for comparison to a commercially available Free T4 EIA. Range tested: VIDAS® (0.41 - 6.42 ng/dL), miniVIDAS® (0.52 - 6.35 ng/dL). This data is prospectively generated.
Reference Range / Expected Values: 544 apparently healthy subjects. The population characteristics are described (45.5% males, 55.5% female, 83.8% Caucasian, 6.1% African-American, 9.6% Hispanic and 0.6% Asian). The country of origin is not specified but the demographic breakdown suggests a Western population. This is prospective data collection.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

For an IVD device like VIDAS® FT4, "ground truth" is typically established by:

Using reference materials with assigned values.
Comparing to a legally marketed predicate device or a well-established, validated method (e.g., mass spectrometry, if applicable, though not explicitly mentioned here as a primary reference method).
For clinical studies like reference range determination, it relies on clinical assessment of health status (e.g., "apparently healthy subjects").

In this documentation:

Metrological traceability: The VIDAS® FT4 assay is standardized against the Elecsys® FT4 assay (Roche Diagnostic), which serves as a clinical reference method (predicate device).
Value assignment procedure for calibrator (S1) and control (C1): Reference Calibrators are assigned values via a method comparison between VIDAS® FT4 and Roche Elecsys FT4.
Correlation study: The VIDAS® FT4 assay was compared to a commercially available Free T4 EIA (likely the predicate Elecsys® FT4 Assay or similar). This serves as the ground truth for that specific study.
Reference Range / Expected Values: This ground truth is based on the clinical status of "apparently healthy subjects." There is no mention of "experts" in the sense of clinicians or radiologists establishing ground truth for individual cases. The health status of the subjects would be determined by standard medical screening procedures, presumably overseen by medical professionals (e.g., physicians, lab personnel) but not explicitly detailed as "experts."

Therefore, there isn't a stated number of experts or specific qualifications in the traditional sense of consensus reading for image or pathology-based diagnostics. The ground truth relies on established analytical methods and clinical definitions of health.

4. Adjudication Method for the Test Set

Not applicable in the context of this IVD device's analytical and clinical performance studies as described. Adjudication (e.g., 2+1, 3+1) is typically used for resolving discrepancies in expert interpretations in studies involving subjective assessments (like radiology or pathology image analysis). For quantitative assays, the "ground truth" is determined by reference methods or validated values, not by expert consensus on individual results.

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

Not applicable. This is an in vitro diagnostic (IVD) device for quantitative measurement of free thyroxine (FT4). It is not an AI-assisted diagnostic imaging or pathology device that involves human readers interpreting cases.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was Done

Yes, the studies presented are all standalone performance evaluations of the VIDAS® FT4 assay system (instrument + reagents + algorithm), which is an automated system designed to provide quantitative results directly. The results are "automatically calculated by the instrument in relation to the calibration curve stored in memory, and then printed out." Human involvement is limited to operating the instrument, performing calibration, and reviewing the generated reports, not to interpreting raw data points or making subjective diagnostic decisions the device is intended to automate.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)

The ground truth used primarily consists of:

Reference Method Comparison: For several studies, the predicate Elecsys® FT4 assay or another commercially available, validated Free T4 EIA served as the comparative "ground truth" or reference method for demonstrating substantial equivalence.
Reference Materials: For analytical sensitivity (LoB, LoD, LoQ) and linearity, the ground truth is based on gravimetrically prepared or otherwise certified reference materials with known concentrations.
Clinical Definition: For the reference range determination, the ground truth for the healthy population was based on subjects deemed "apparently healthy."

8. The sample size for the training set

This document describes the validation of an IVD assay, not a machine learning or AI algorithm in the context of "training data." The assay relies on a pre-defined chemical reaction and detection method, with instrument calibration. Therefore, there is no "training set" in the sense of data used to train a predictive model. The "calibration curve" is established using a set of calibrators with known concentrations, which is a standard procedure for quantitative assays and not an AI training process.

9. How the ground truth for the training set was established

As there is no "training set" for an AI algorithm in this context, this question is not applicable. For the calibration of the assay, the "ground truth" (assigned values for calibrators) is established through reference method comparison with the Elecsys® FT4 assay and potentially other established metrological traceability chains, as described under "Value assignment procedure for calibrator (S1) and control (C1)."

Summary

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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002

BIOMERIEUX SA AURELIE PERMEZEL REGULATORY AFFAIRS SPECIALIST 5 RUE DES AQUEDUCS CRAPONNE 69290 FRANCE

June 8, 2015

Re: K132058

Trade/Device Name: VIDAS® FT4 Regulation Number: 21 CFR 862.1695 Regulation Name: Free thyroxine test system Regulatory Class: II Product Code: CEC Dated: May 26, 2015 Received: May 27, 2015

Dear Aurelie Permezel:

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 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.

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If you desire specific advice for your device on our labeling regulations (21 CFR Parts 801 and 809), 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" (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 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,

Katherine Serrano -S

For:

Courtney H. Lias, Ph.D. Director Division of Chemistry and Toxicology 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) K132058

Device Name VIDAS® FT4

Indications for Use (Describe)

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 information is being submitted in accordance with the requirement of SMDA 1990 and 21 CFR 807.92.

VIDAS® FT4

A. Submitter Information

Submitter's Name:	bioMérieux SA
Address:	5 rue des Aqueducs69290 Craponne - France
Contact Person:	Aurélie PERMEZEL
Phone Number:	+33 4 78 87 74 83
Fax Number:	+33 4 78 87 20 75
Date of Preparation:	May 26th, 2015

B. Device Name

Trade Name:	VIDAS®FT4
Common Name:	FT4 Assay
Classification Name:	21 CFR 862.1695 - Free thyroxine test system, Class IIProduct code CEC

C. Predicate Device Name

Trade Name:	Elecsys® FT4 Assay (K961489)
-------------	------------------------------

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D. Device Description

VIDAS® FT4 is an automated quantitative enzyme immunoassay for use on the instruments of the VIDAS® family, for the determination of free thyroxine (FT4) in human serum or plasma (lithium heparin), using the ELFA technique (Enzyme Linked Fluorescent Assay). Measurement of free thyroxine is intended for use as an aid in the diagnosis and treatment monitoring of thyroid disorders.

The assay principle combines a one-step enzyme immunoassay competition method with a final fluorescent detection (ELFA).

E. Intended Use

VIDAS® FT4 is an automated quantitative enzyme immunoassay for use on the instruments of the VIDAS® family, for the determination of free thyroxine (FT4) in human serum or plasma (lithium heparin), using the ELFA technique (Enzyme Linked Fluorescent Assay). Measurement of free thyroxine is intended for use as an aid in the diagnosis and treatment monitoring of thvroid disorders.

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F. Technological Characteristics Summary

A general comparison of the similarities and differences of the assays is presented in the table below.

Item	VIDAS® FT4 assay	Elecsys® FT4 Assay (K961489)
General Comparison
Intended Use	VIDAS® FT4 is an automated quantitative enzyme immunoassay for use on the instruments of the VIDAS® family, for the determination of free thyroxine (FT4) in human serum or plasma (lithium heparin), using the ELFA technique (Enzyme Linked Fluorescent Assay). Measurement of free thyroxine is intended for use as an aid in the diagnosis and treatment monitoring of thyroid disorders.	Immunoassay for the in vitro quantitative determination of free thyroxine in human serum and plasma. The electrochemiluminescence Immunoassay “ECLIA" is intended for use on Elecsys and Cobas e immunoassay analysers.
Specimen	Serum and plasma	Same
Analyte	Free thyroxine	Same
Automated	Yes	Same
Assay Technique	Enzyme-linked fluorescent assay (ELFA)	Electrochemiluminescence Immunoassay “ECLIA”
Assay Principle	Labeled antibody competition method	Same

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G. Nonclinical Tests

A summary of the performance results is presented in the table below.

Analytical specificity

Interferences with bilirubin, lipids, hemoglobin, HAMA (human anti-mouse antibodies), albumin and TBG (Thyroid binding globulin):

Interferences have been studied according to the recommendations of CLSI® document EP7-A2.

The following substances, studied in serum at FT4 analyte levels close to the lower and higher limits of the euthyroid range, showed no significant interference up to the concentration indicated, on the instruments of the VIDAS® family.

Bilirubin	22.5 mg/dL
Lipids	750 mg/dL
Hemoglobin	500 mg/dL
HAMA	0.2 mg/dL
Albumin	6300 mg/dL

Samples containing abnormal TBG levels (very high or very low) should be not used with this assav.

No interference was observed with samples containing HAMA up to 0.2 mg/dL when tested with VIDAS® FT4 assay. For assays employing antibodies, the possibility exists for interference by heterophile antibodies in the patient sample. Patients who have been regularly exposed to animals or have received immunotherapy or diagnostic procedures utilizing immunoglobulins or immunoglobulin fragments may produce antibodies, e.g. HAMA, that interfere with immunoassays. Additionally, other heterophile antibodies such as human anti-goat antibodies may be present in patient samples. Such interfering antibodies may cause erroneous results. Carefully evaluate the results of patients suspected of having these antibodies.

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Drugs interferences:

The following drugs, showed no significant interference up to the concentration indicated.

Drug	Highest concentration at which nointerference was observed
Acetylsalicylic Acid	32.61 mg/dL
Amiodarone	0.58 mg/dL
Carbamazepine	1.5 mg/dL
Danazol	24 mg/dL
Diclofenac	0.315 mg/dL
Diphenyldantoin	2.5 mg/dL
Dipyrone	580.08 mg/dL
Furosemide	0.075 mg/dL
Isotretinonine	1.20 mg/dL
Lithium	13.56 mg/dL
Mefenamic Acid	0.5625 mg/dL
Mestranol	0.002 mg/dL
Methimazole	2.40 mg/dL
Norethindrone	0.001 mg/dL
Phenylbutazone	5 mg/dL
Propanolol	0.20 mg/dL
Propylthiouracil	3.08 mg/dL

Potential interferences of structurally related molecules:

The following substances showed no significant interference with tested FT4 concentrations of approximately 1.2 ng/dL and 2.5 ng/dL:

Tested compound	No interference* observed up to theconcentration of	Cross reactivity (%) *
3,5-diiodotyrosine	16.770 µg/dL (167.70 µg/L)	0.00095 %
3,5-diodothyronine	27.310 µg/dL (273.10 µg/L)	0.00040 %
L-triiodothyronine	0.678 µg/dL (6.78 µg/L)	0.02655 %

*The studies were performed according to the recommendation of the CLSI document EP07-A2 up to the concentration indicated on the VIDAS and miniVIDAS instruments.

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Analytical sensitivity

Detection and quantitation limits studies were performed on both VIDAS® instruments determined according to CLSI EP17-A2 recommendations. The limits reported below applies for both instruments:

Limit of Blank (LoB): 0.02 ng/dL Limit of Detection (LoD): 0.07 ng/dL Limit of Quantitation (LoQ): 0.13 ng/dL

The Limit of Blank (LoB) was determined using one blank sample tested in 12 replicates per day (single run on VIDAS® instrument, 2 runs on miniVIDAS® instrument) for 5 days with each lot (2 lots on one VIDAS® instrument and 1 lot on one miniVIDAS® instrument). N=60 measures per lot on each instrument.

The Limit of Detection (LoD) was determined using low concentration samples on VIDAS® instrument, 4 samples on miniVIDAS® instrument), tested inn 5 replicates per day
(single run) for 5 days with each lot(2 lots on one VIDAS® instrument and 1 lot on one miniVIDAS® instrument). N=150 measures per lot on VIDAS® instrument and N=100 measures per lot on miniVIDAS® instrument.

The Limit of Quantitation (LoQ), as determined by functional sensitivity, corresponds to the lowest analyte concentration that can be reproducibly measured with a within-laboratory precision CV of ≤ 20 %. It was determined based on the within-laboratory precision profile estimated using 9 low concentration samples tested in 5 replicates per day (single run) for 8 days with 2 lots, on one VIDAS® instrument and one miniVIDAS® instrument. N=40 measures per sample and per lot on each instrument.

Measurement range

The VIDAS® FT4 measurement range extends from 0.13 ng/dL up to 6.61 ng/dL. Values below the lower limit of the measurement range are reported as < 0.13 ng/dL. Values above the upper limit of the measurement range are reported as > 6.61 ng/dL.

Metrological traceability

The VIDAS® FT4 assay is standardized against the Elecsys® FT4 assay (Roche Diagnostic).

Value assignment procedure for calibrator (S1) and control (C1)

Reference Calibrators are assigned values via a method comparison between VIDAS® FT4 and Roche Elecsys FT4. The VIDAS® FT4 kit calibrator (S1) and control (C1) are assigned values based upon these reference calibrators.

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Linearity

The VIDAS® FT4 assay is linear over the whole measurement range (0.13 ng/dL to 6.61 ng/dL). The linearity was conducted on the VIDAS® and the miniVIDAS® instruments and evaluated according to the recommendations of CLSI® document EP6-A.

Matrix Comparison

A matrix comparison study was performed using 31 sample sets. Each sample set consisted of a reference tube type (Silicone coated glass tube) and one of the blood collection tubes (Plastic tube with clot activator, Plastic tube with clot activator and separation gel, Plastic tube with lithium heparin, Plastic tube with lithium heparin and separation gel) collected from one donor during one draw. Samples between 0.13 ng/dL to 6.45 ng/dL were analyzed on VIDAS® instrument. Passing-Bablok regression was used to compare the samples collected in the reference tube (x) and the samples collected in each collection tube (y) after 24 hours at 18-25°C:

Collection tube	Regression analysis	Correlation coefficient(r)
Plastic tube with clot activator	Y = 0.98X + 0.01	0.999
Plastic tube with separation gel	Y = 1.02X + 0.02	0.999
Plastic tube with lithium heparin	Y = 0.99X - 0.01	0.997
Plastic tube with lithium heparinand separation gel	Y = 1.00 X + 0.00	0.999

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H. Clinical Tests

Precision

The study was performed according to the recommendations of CLSI® document EP5-A2. Panel members covering the measuring range were tested in duplicate, in 2 runs per day, for 20 days, on 3 VIDAS® and 3 miniVIDAS® instruments . Testing included 2 lots with 10 days per lot. For each lot, 2 separate calibrations were performed. There were 5 testing days per calibration per lot.

The precision performance characteristics of the VIDAS® FT4 assay using 6 samples tested on VIDAS® instruments, are as follows:

Sample	N	Mean(ng/dL)	Repeatability		Reproducibility
			SD (ng/dL)	CV (%)	SD (ng/dL)	CV (%)
S1	240	0.31	0.02	6.3	0.04	13.4
S2	240	0.79	0.03	3.6	0.07	8.3
S3	240	1.54	0.05	3.1	0.11	7.4
S4	240	2.57	0.06	2.5	0.13	5.1
S5	240	4.00	0.09	2.3	0.24	5.9
S6	240	5.78	0.17	3.0	0.38	6.5

The precision performance characteristics on 5 samples tested on miniVIDAS® instruments, are as follows:

Sample	N	Mean(ng/dL)	Repeatability		Reproducibility
			SD (ng/dL)	CV (%)	SD (ng/dL)	CV (%)
P1	240	0.24	0.03	11.2	0.04	15.4
P2	240	0.78	0.03	3.7	0.04	5.6
P3	240	1.45	0.05	3.3	0.07	4.9
P4	240	3.04	0.07	2.3	0.10	3.4
P5	240	5.64	0.11	2.0	0.16	2.8

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Correlation

A method comparison study was performed to compare VIDAS® FT4 assay to a commercially available Free T4 EIA according to the recommendations of the CLSI® document EP9-A2.

The VIDAS® FT4 assay was tested on both VIDAS® and miniVIDAS® instruments. Fifty-four (54) samples were included in the study.

The results of the correlations are shown below:

Instrument	n	Rangetested(ng/dL)	Slope	95% Cl	Intercept	95% Cl	Correlationcoefficient(r)	95% Cl
VIDAS®	54	0.41 - 6.42	1.03	0.99 : 1.06	-0.02	-0.13 : 0.05	0.988	0.980 : 0.993
miniVIDAS®	54	0.52 - 6.35	1.04	1.00 ; 1.08	0.01	-0.06 ; 0.12	0.987	0.977 : 0.992

Reference range / Expected Values

The 2.5th and 97.5th percentiles reference interval for the VIDAS® FT4 assay was determined to be 0.77 -1.51 ng/dL. The 90% confidence interval for the lower limit was 0.70 - 0.79 ng/dL and the 90% confidence interval for the upper limit was 1.41 - 1.59 ng/dL. The reference range was determined by testing a total of 544 apparently healthy subjects from a population > 18 years in age with the following characteristics: 45.5% males, 55.5% female, 83.8% Caucasian, 6.1% African-American, 9.6% Hispanic and 0.6% Asian.

I. Conclusion

The results from the nonclinical and clinical studies submitted in this premarket notification are complete and demonstrate that the VIDAS® FT4 is substantially equivalent to the predicate device identified in Item C of this summary.

Regulation Number and Section

§ 862.1695 Free thyroxine test system.

(a)
Identification. A free thyroxine test system is a device intended to measure free (not protein bound) thyroxine (thyroid hormone) in serum or plasma. Levels of free thyroxine in plasma are thought to reflect the amount of thyroxine hormone available to the cells and may therefore determine the clinical metabolic status of thyroxine. Measurements obtained by this device are used in the diagnosis and treatment of thyroid diseases.(b)
Classification. Class II.