The ARCHITECT Free T4 (FT4) assay is a Chemiluminescent Microparticle Immunoassay (CMIA) for the quantitative determination of free thyroxine (Free T4) in human serum and plasma.

ARCHITECT Free T4 (FT4) assay is to be used as an aid in the assessment of thyroid status.

Device Description

The ARCHITECT Free T4 assay is a two-step immunoassay for the quantitative determination of free thyroxine (Free T4) in human serum and plasma using CMIA technology with flexible assay protocols, referred to as Chemiflex.

In the first step, sample and anti-T4 coated paramagnetic microparticles are combined. Free T4 (unbound) present in the sample binds to the anti-T4 coated microparticles. After washing, Ts acridinium-labeled conjugate is added to create a reaction mixture. Following another wash cycle, pre-trigger and trigger solutions are added to the reaction mixture. The resulting chemiluminescent reaction is measured as relative light units (RLUs). An inverse relationship exists between the amount of Free T4 in the sample and the RLUs detected by the ARCHITECT i System optics.

AI/ML Overview

The provided text describes a 510(k) premarket notification for a modification to the ARCHITECT Free T4 assay, not a study proving device meets acceptance criteria in the context of AI/ML or comparative effectiveness. The device is an in-vitro diagnostic (IVD) test, and the information requested about AI/ML models, human readers, and ground truth types (pathology, outcomes data) is not applicable to this type of device or documentation.

However, I can extract the acceptance criteria and performance data related to the nonclinical performance verification for the modified ARCHITECT Free T4 assay, as presented in the document.

Acceptance Criteria and Reported Device Performance

The device under review is an in-vitro diagnostic (IVD) assay, not an AI/ML device. Therefore, acceptance criteria and performance are based on analytical performance studies. The document states that the "device passed all of the tests based on pre-determined acceptance criteria." While the specific numerical acceptance criteria are not detailed in this summary, the types of tests performed and the general outcome are reported.

Acceptance Criteria Category	Reported Device Performance
Limit of Blank/Detection/Quantitation	Device passed based on pre-determined acceptance criteria.
Precision (20-Day)	Device passed based on pre-determined acceptance criteria.
Precision at Limits of Measuring Interval	Device passed based on pre-determined acceptance criteria.
Accuracy by Correlation	Device passed based on pre-determined acceptance criteria.
Accelerated Life Testing (ALT) Stability	Device passed based on pre-determined acceptance criteria.
Reagent On Board Stability	Device passed based on pre-determined acceptance criteria.
Linearity	Device passed based on pre-determined acceptance criteria.

1. Sample sized used for the test set and the data provenance:

The document does not specify the exact sample sizes used for each individual nonclinical performance study (Limit of Blank/Detection/Quantitation, Precision, Accuracy, Stability, Linearity). It also does not explicitly state the country of origin of the samples or if they were retrospective or prospective, though for IVD analytical performance, these would typically be control samples and patient samples collected for various analytical evaluations to represent the intended use population.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

Not applicable. For an immunoassay, the "ground truth" for analytical performance studies is established by the assay's ability to accurately and precisely measure the analyte (Free T4) in samples against known concentrations or reference methods, not by expert interpretation of images or clinical data.

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

Not applicable. Adjudication methods like 2+1 are used for expert consensus on subjective interpretations (e.g., radiology reads), which is not relevant for an IVD analytical performance study.

4. 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 IVD assay, not an AI/ML diagnostic tool involving human readers.

5. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:

Not applicable. This is an IVD immunoassay, not an algorithm or AI model. Its performance is inherent to the assay chemistry and instrument.

6. The type of ground truth used:

For the analytical performance studies, the "ground truth" is established through:

Known concentrations: For studies like linearity, limits, and precision, samples with known concentrations of Free T4 would be used.
Reference methods/comparative methods: For accuracy by correlation, the results of the ARCHITECT Free T4 assay would be compared against a legally marketed predicate device (as referenced, K123379) or a recognized reference method.

7. The sample size for the training set:

Not applicable. This is an immunoassay, not an AI/ML model, so there is no "training set" in the computational sense. The development of the assay reagents and protocols is based on chemical and biological research and optimization.

8. How the ground truth for the training set was established:

Not applicable, as there is no "training set" in the context of an AI/ML model. The development of the assay components (reagents, microparticles, conjugate) and the associated manufacturing process enhancement (reduced microparticle percent solids) are validated through the nonclinical performance studies listed.

Summary

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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002 October 27, 2017

ABBOTT LABORATORIES LINDA SOHN REGULATORY AFFAIRS PROJECT MANAGER DEPT. 09AA, BLDG. AP08 100 ABBOTT PARK ROAD ABBOTT PARK IL 60064

Re: K173122

Trade/Device Name: ARCHITECT Free T4 Regulation Number: 21 CFR 862.1695 Regulation Name: Free thyroxine test system Regulatory Class: II Product Code: CEC Dated: September 28, 2017 Received: September 29, 2017

Dear Linda Sohn:

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/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 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,

Kellie B. Kelm -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)

K173122 Device Name ARCHITECT Free T4

Indications for Use (Describe)

The ARCHITECT Free T4 (FT4) assay is a Chemiluminescent Microparticle Immunoassay (CMA) for the quantitative determination of free thyroxine (Free T4) in human serum and plasma.

ARCHITECT Free T4 (FT4) assay is to be used as an aid in the assessment of thyroid status.

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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I. 510(k) Summary

This summary of the 510(k) safety and effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92.

Date: September 28, 2017

Applicant Name:

Linda Sohn, ADD, Regulatory Affairs Project Manager Abbott Laboratories Diagnostics Division Dept. 09AA, AP08 100 Abbott Park Road Abbott Park, IL 60064 Telephone Number: (224) 667-4846 Fax Number: (224) 667-4836

Device Name:

Reagents

Classification Name: Free thyroxine test system Trade Name: Abbott ARCHITECT Free T4 Common Name: Radioimmunoassay, Free Thyroxine Governing Regulation: 21 CFR 862.1695 Device Classification: Class II Classification Panel: Clinical Chemistry Product Code: CEC

Legally marketed device to which equivalency is claimed:

ARCHITECT Free T4 (cleared under K123379 on November 27, 2012)

Intended Use/Indications for Use:

The ARCHITECT Free T4 (FT4) assay is a Chemiluminescent Microparticle

Immunoassay (CMIA) for the quantitative determination of free thyroxine (Free T4) in human serum and plasma.

ARCHITECT Free T4 (FT4) assay is to be used as an aid in the assessment of thyroid status.

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Description of Device

Modification of Device:

This Special 510(k) modification of the ARCHITECT Free T4 assay consisted of proposed labeling change for reduced microparticle percent solids from 0.08% to 0.05% due to enhancement of our manufacturing process, and proposed labeling change for reduced measuring interval from 0.40 to 6.00 ng/dL to 0.40 to 5.00 ng/dL.

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Similarities and Differences of Modified Device

The table below compares the modified device, (ARCHITECT Free T4) and the predicate device (ARCHITECT Free T4 [K123379]).

Characteristics	Predicate Device (K123379)	Modified Device
Intended Use /	The ARCHITECT Free T4 (FT4) assay is a chemiluminescentmicroparticle immunoassay (CMIA) for the quantitativedetermination of Free T4 in human serum and plasma.
Indications for Use	ARCHITECT Free T4 (FT4) assay is to be used as an aid in theassessment of thyroid status.
Platform	ARCHITECT i System
Methodology	Chemiluminescence (CMIA)
Specimen Type	Serum and plasma
Microparticles	Anti-T4 (sheep) coatedMicroparticles in TRIS bufferwith sheep IgG stabilizers.Preservative: sodium azide.Percent solids: 0.08%	SamePercent solids: 0.05%
Conjugate	T3 acridinium-labeledConjugate in MES buffer withNaCl and Triton X-100stabilizers. Preservative:ProClin.Minimum concentration: 0.2ng/mL.	same
Calibrators	• 6 levels• 0.0, 0.5, 1.0, 2.0, 3.5, 6.0ng/dLL-thyroxine in human serum	same
Measuring Interval	0.40-6.00 ng/dL	0.40-5.00 ng/dL

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Verification of Modification:

The nonclinical performance of the ARCHITECT Free T4 assay was demonstrated through the following studies:

. Limit of Blank/Detection/Quantitation
Precision (20-Day)
. Precision at Limits of Measuring Interval
Accuracy by Correlation
. Accelerated Life Testing (ALT) Stability
Reagent On Board Stability
Linearity

The device passed all of the tests based on pre-determined acceptance criteria.

Conclusion:

Substantial equivalence for the modified device, ARCHITECT Free T4 is claimed to the predicate device cleared in K123379, ARCHITECT Free T4. The modifications to the labeling, which consisted of proposed labeling change for reduced microparticle percent solids from 0.08% to 0.05%, and proposed labeling change for reduced measuring interval from 0.40 to 6.00 ng/dL to 0.40 to 5.00 ng/dL, has not changed the intended use, indications for use, nor has it altered the fundamental scientific technology of the device. Furthermore, no new risks or modes of control that affect the safety and effectiveness of the device were identified as a result of the proposed change.

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.