Osteomark is a urinary assay that provides a quantitative measure of the excretion of cross-linked N-telopeptides of type I collagen (NTx) as an indicator of human bone resorption. Elevated levels of urinary NTx indicate elevated human bone resorption. Measurement of NTx is intended for use in:

A. Predicting skeletal response (bone mineral density) to hormonal antiresorptive therapy in postmenopausal women.

B. Therapeutic monitoring of:

1. antiresorptive therapies in postmenopausal women
1. antiresorptive therapies in individuals diagnosed with osteoporosis
1. antiresorptive therapies in individuals diagnosed with Paget's disease of bone

estrogen-suppressing therapies

C. Assessing the relative risk for loss of spinal bone mass after one year if not treated with hormonal antiresorptive therapy

Device Description

Osteomark is a competitive enzyme-linked immunosorbent assay (ELISA) which utilizes a horseradish peroxidase labeled monoclonal antibody directed against the cross-linked N-telopeptides (NTx) present in urine specimens. An Osteomark® kit is comprised of the following reagents:

Antigen Coated 96-Well Plate Calibrators: 1 nM BCE 30 nM BCE 100 nM BCE 300 nM BCE 1000 nM BCE 3000 nM BCE Antibody Conjugate Concentrate Antibody Conjugate Diluent Level I and Level II Urine Controls 30X Wash Concentrate Buffered Substrate Chromogen Reagent Stopping Reagent

The solid phase utilizes microwells onto which NTx has been adsorbed. NTx in the specimen or Calibrator competes with the solid phase NTx for antibody binding sites. The resulting amount of Antibody Conjugate bound to the solid phase is indirectly proportional to the amount of NTx in the specimen or Calibrator. The quantity of NTx in the specimen is determined from a standard calibration curve using reagents supplied in the kit. Assay values are standardized to an equivalent amount of bone collagen, and are expressed in nanomole bone collagen equivalents per liter (nM BCE). BCE reflects the amount of immunoreactive NTx, as measured by Osteomark, liberated from human bone collagen following digestion with bacterial collagenase, as measured by hydroxyproline by high performance liquid chromatography (HPLC).

AI/ML Overview

Here's an analysis of the provided text, outlining the acceptance criteria and the studies performed for the Osteomark® device:

Acceptance Criteria and Device Performance Study for Osteomark®

The Osteomark® device is a urinary assay designed to quantitatively measure N-telopeptides of type I collagen (NTx) as an indicator of human bone resorption. The provided documentation details several performance characteristics and studies that likely served as the basis for acceptance criteria.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state acceptance criteria with defined pass/fail thresholds for a regulatory submission. Instead, it presents performance characteristics and reference ranges derived from studies. Based on the "Performance Characteristics" section, we can infer the following:

Acceptance Criteria (Inferred)	Reported Device Performance
Expected Values:
Premenopausal Women (mean age 36)	Mean: 35 nM BCE/mmol creatinine, Std Dev: 15, Range: 9-84
Postmenopausal Women (<3 yrs post-menopause, mean age 51)	Mean: 65 nM BCE/mmol creatinine, Std Dev: 33, Range: 23-188
Lower Limit of Detection:	20 nM BCE
Interfering Substances:	Showed interference with whole blood or extensive hemolysis.
Reproducibility (Intra-assay):	Average 8% CV (range 5-19% CV)
Reproducibility (Inter-assay):	Average 4% CV (range 3-5% CV)
Antigen Recovery:	Average 105% recovery
Dilutional Linearity:	Correlation coefficients of r=0.999 to r=1.000

2. Sample Sizes Used for Test Sets and Data Provenance

The studies described are primarily for establishing expected values and performance characteristics rather than a single "test set" for a diagnostic accuracy study as might be seen for an imaging AI.

Expected Values - Premenopausal Women:
- Sample Size: 186
- Data Provenance: Multi-center, cross-sectional study. Data from "normal premenopausal women without diseases, disorders, or currently taking medications which may affect bone metabolism or creatinine excretion." (Country of origin not specified, but the regulatory approval is US FDA).
- Retrospective/Prospective: Implied prospective, as it describes a study being "conducted."
Expected Values - Postmenopausal Women:
- Sample Size: 91
- Data Provenance: Additional multi-center, cross-sectional study. Subjects without diseases, disorders, or currently taking medications known to affect bone metabolism or creatinine excretion. (Country of origin not specified).
- Retrospective/Prospective: Implied prospective.
Intra-assay Variability (Reproducibility):
- Sample Size: Eight urine specimens, tested in replicates of 10.
- Data Provenance: Normal urine specimens. (Origin not specified).
Inter-assay Variability (Reproducibility):
- Sample Size: Three urine specimens, tested in duplicate over 20 separate assay runs.
- Data Provenance: Normal urine specimens. (Origin not specified).
Antigen Recovery:
- Sample Size: Three normal urine specimens.
- Data Provenance: Normal urine specimens. (Origin not specified).
Dilutional Linearity:
- Sample Size: Four urine specimens.
- Data Provenance: Urine specimens with high nM BCE values and a urine specimen with a low nM BCE value. (Origin not specified).
Interfering Substances:
- Sample Size: Not explicitly stated, implied to be multiple normal urine specimens.
- Data Provenance: Normal urine specimens. (Origin not specified).

3. Number of Experts Used to Establish Ground Truth and Qualifications

For this type of in-vitro diagnostic (IVD) device, "ground truth" is typically established through biochemical methods and clinical classification based on objective criteria, not through expert reading or interpretation in the same way as an imaging AI.

Ground Truth for Expected Values: The classification of subjects as "premenopausal" or "postmenopausal" (and "normal" without affecting conditions) would be based on medical history, clinical evaluation, and potentially hormone levels, managed by medical professionals involved in the multi-center studies. The NTx levels themselves are the measurement, not an interpretation of an image.
Ground Truth for Performance Characteristics: The "ground truth" for reproducibility, linearity, and recovery is inherent in the known concentrations of analytes or the statistical methods used to quantify variability. No external "experts" are mentioned for establishing ground truth beyond the standard laboratory practices and quality control.

4. Adjudication Method for the Test Set

Adjudication methods like 2+1 or 3+1 are relevant for subjective interpretations, often in imaging studies where readers might disagree. For an ELISA-based IVD like Osteomark®, the analysis is quantitative and objective, based on optical density readings and calculation from a standard curve. Therefore, such adjudication methods are not applicable and not mentioned for this device. The results are generated by the assay and interpreted against established normative data.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No. An MRMC comparative effectiveness study is designed to assess how human readers' performance (e.g., accuracy, efficiency) changes with and without the assistance of an AI algorithm, specifically in diagnostic tasks involving human interpretation (e.g., radiology). The Osteomark® is an automated quantitative assay (an ELISA kit) that provides a numerical result; it does not involve human "readers" interpreting output in the same way an AI for image analysis would. Therefore, this type of study is not relevant or applicable to this device.

6. Standalone (Algorithm Only) Performance Study

Yes, implicitly. The entire "Performance Characteristics" section describes the standalone performance of the Osteomark® assay. The device itself is an "algorithm" (a biochemical assay protocol) that generates a quantitative result. The reproducibility, antigen recovery, and dilutional linearity tests are all evaluations of the assay's performance without human influence on the measurement itself, beyond the correct execution of the protocol. The device provides a direct numerical output (nM BCE/millimole creatinine) without requiring human interpretation of a complex signal for diagnosis, unlike an imaging AI.

7. Type of Ground Truth Used

For Expected Values / Reference Ranges: The ground truth used is clinical classification based on demographic (menopausal status) and health criteria, combined with biochemical measurements (NTx levels, creatinine) from the study subjects. The NTx level itself, standardized to creatinine, is the quantitative output.
For Performance Characteristics (Reproducibility, Linearity, Recovery): The ground truth is established through known concentrations of analytes (e.g., adding known amounts of NTx for antigen recovery) or statistical definitions of variability for precision studies.

8. Sample Size for the Training Set

The concept of "training set" is primarily relevant for machine learning algorithms where data is used to teach a model. For a traditional ELISA immunoassay like Osteomark®, there isn't a "training set" in the machine learning sense.

However, the calibration curve within each assay run could be considered analogous to a "training" component for individual measurements. The kit includes:

Calibrators: 1 nM BCE, 30 nM BCE, 100 nM BCE, 300 nM BCE, 1000 nM BCE, 3000 nM BCE.
- This constitutes the data points (known concentrations) used to construct the standard curve, from which unknown specimen concentrations are interpolated. The number of calibrators is 6.

9. How the Ground Truth for the Training Set Was Established

For the Osteomark® assay, the "ground truth" for its internal calibration (the calibrators) is established by precise biochemical preparation and quantification of known concentrations of cross-linked N-telopeptides of type I collagen (NTx). These calibrators are rigorously prepared and verified standards to ensure accurate determination of NTx in patient samples. The document mentions "BCE reflects the amount of immunoreactive NTx, as measured by Osteomark, liberated from human bone collagen following digestion with bacterial collagenase, as measured by hydroxyproline by high performance liquid chromatography (HPLC)." This indicates that the BCE values, and thus the calibrator values, are traceable to well-established analytical methods.

Summary

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SECTION 1: REGULATORY INFORMATION SUMMARY OF SAFETY AND EFFECTIVENESS

MAR - 6 1998

280518

Osteomark® is a urinary assay that provides a quantitative measure of the excretion of cross-linked N-telopeptides of type I collagen (NTx) as an indicator of human bone resorption. Elevated levels of urinary NTx indicate elevated human bone resorption. Measurement of NTx is intended for use in:

A. Predicting skeletal response (bone mineral density) to hormonal antiresorptive therapy in postmenopausal women.

B. Therapeutic monitoring of:

1. antiresorptive therapies in postmenopausal women
1. antiresorptive therapies in individuals diagnosed with osteoporosis
1. antiresorptive therapies in individuals diagnosed with Paget's disease of bone

estrogen-suppressing therapies

C. Assessing the relative risk for loss of spinal bone mass after one year if not treated with hormonal antiresorptive therapy

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30X Wash Concentrate Buffered Substrate Chromogen Reagent Stopping Reagent

Expected Values

Urine Collection:

A multi-center, cross-sectional study was conducted in order to compare the results obtained with either a second morning void (SMV) spot urine collection or a 24 hour urine collection in Osteomark®. The population tested represented 186 normal premenopausal women without diseases, disorders, or currently taking medications which may affect bone metabolism or creatinine excretion.

The SMV mean was 35 (+/- 15) nanomoles BCE/millimole creatinine. The 24 hour urine specimens, normalized for urinary creatinine, had a mean of 26 (+/- 13) nanomoles BCE/millimole creatinine.

Reference Range Data:

In the same study discussed above, the expected values for premenopausal women with the Osteomark® assay were determined. An additional multi-center, cross-sectional

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study involving subjects without diseases, disorders, or currently taking medications known to affect bone metabolism or creatinine excretion was conducted to establish the expected values for postmenopausal women. The comparative results are presented in Table 1 below.

Study Group	Mean*	Std Dev	Range*	N
Premenopausal Women(mean 36 years, range 25-49)	35	15	9-84	186
Postmenopausal Women(< 3 years postmenopause,mean 51 years, range 40-58)	65	33	23-188	91

Table 1 - Expected Osteomark® Values (nM BCE/millimole creatinine)

Limitations of the Procedure

Lower Limit of Detection

The lower limit of detection of the Osteomark® assay is 20 nM BCE. This value represents a concentration which is greater than the value which can be distinguished from zero, and was calculated by subtracting 3 standard deviations optical density (A450-A630) from established variability of the 1nM BCE Calibrator. Assay precision below this value is insufficient for accurate results.

Interfering Substances

Common urine components and contaminants, as well as microbiological contaminants, that are known to interfere with many laboratory urine analyses were evaluated for an interfering effect with Osteomark®. The evaluations were performed by adding normal and excessive quantities of each potential inhibitor to normal urine specimens and analyzing for an effect on the final results. Results show that specimens obviously

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contaminated with whole blood or that have extensive hemolysis may show interference in the assay. These specimens should be avoided, and the specimen recollected.

Performance Characteristics

Reproducibility

Assay reproducibility was evaluated for intra-assay and inter-assay variability of normal urine specimens across the range of the calibration curve.

Intra-assay variability, or within assay precision, was assessed using eight urine specimens tested in replicates of 10 by each of four operators. Results demonstrate an average intra-assay variability estimate of 8% CV, with a range of 5-19% CV along the calibration curve.

Inter-assay variability, or assay to assay precision, was assessed using three urine specimens tested in duplicate by one operator over 20 separate assay runs. Results demonstrate an average interassay variability estimate of 4% CV, with a range of 3-5% CV along the calibration curve.

Antigen Recovery

Antigen recovery was evaluated by adding known amounts of NTx to each of three normal urine specimens. Recovery represented the observed assay value of the "spiked" specimens, calculated as a percent of the expected urine value (baseline urine value plus added antigen value). Results demonstrate an average antigen recovery of 105%, over an assay value range of 200-2500 nM BCE.

Dilutional Linearity

Dilutional linearity was evaluated by performing serial dilutions of four urine specimens with high nM BCE values into a urine specimen with a low nM BCE value. Results

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demonstrated correlation coefficients of r=0.999 to r=1.000 across an assay range of 44-2940 nM BCE.

Osteomark® (PN 9006) Quick Reference

1. Thoroughly read the Assay Procedure before you begin.
1. Bring kit components and specimens to room temperature.
1. Dilute the Antibody Conjugate Concentrate into the Antibody Conjugate Diluent, using a 1:101 ratio.
1. Pipette 25 µL samples of each Calibrator, Control, and specimen into duplicate microwells.
1. Pipette 200 µL of diluted conjugate solution into each microwell. Gently swirl to mix. Incubate the plate at room temperature for 90± 5 minutes.
1. Wash microwells five (5) times with the diluted wash solution, and blot dry.
1. Dilute the Chromogen Reagent into the Buffered Substrate using a 1:101 ratio. Mix gently by inversion only. Do not mix with a stir bar or vortex. Use the Chromogen/Buffered Substrate within 30 minutes of preparation. Add 200 µL of Chromogen/Buffered Substrate to each microwell, and incubate at room temperature for 15 ± 1 minutes.
1. Add 100 µL of Stopping Reagent to each microwell. Then gently swirl the plate for 5 -10 seconds.
1. After five minutes, read the absorbance of each microwell at 450 nm 630 nm. Calculate the results using the standard curve.

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SECTION 1: REGULATORY INFORMATION TRUTHFUL AND ACCURACY STATEMENT

The information contained herein is to the best of my knowledge truthful and accurate.

Harry O'Malley

January 14, 1998
Date

Nancy J.S. Mallinak Vice President, Regulatory and Clinical Affairs Ostex International, Inc.

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Image /page/6/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo consists of a stylized eagle with three stripes forming its body and wing. The eagle faces left and is enclosed within a circular border. The text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" is arranged around the border of the circle.

Food and Drug Administration 2098 Gaither Road Rockville MD 20850

MAR - 6 1998

Nancy J.S. Mallinak . Vice President, Regulatory and Clinical Affairs Ostex International, Inc. 2203 Airport Way South, Suite 400 Seattle, Washington 98134

Re : K980518 Osteomark® Regulatory Class: I Product Code: JMM Dated: January 14, 1998 Received: January 16, 1998

Dear Ms. Mallinak:

We have reviewed your Section 510(k) notification of intent to market the device referenced above and we have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to 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). You may, therefore, market the device, subject to the general controls provisions The general controls provisions of the Act of the Act. include requirements for annual reqistration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.

If your device is classified (see above) into either class II (Special Controls) or class III (Premarket Approval), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Requlations, Title 21, Parts 800 to 895. ਸ substantially equivalent determination assumes compliance with the Current Good Manufacturing Practice requirements, as set forth in the Quality System Regulation (QS) for Medical Devices: General regulation (21 CFR Part 820) and that, through periodic QS inspections, the Food and Drug Administration (FDA) will verify such assumptions. Failure to comply with the GMP regulation may result in regulatory In addition, FDA may publish further announcements action. concerning your device in the Federal Register. Please note: this response to your premarket notification submission does not affect any obligation you might have under sections 531 through 542 of the Act for devices under the Electronic Product Radiation Control provisions, or other Federal laws or regulations.

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Page 2

Under the Clinical Laboratory Improvement Amendments of 1988 (CLIA-88), this device may require a CLIA complexity categorization. To determine if it does, you should contact the Centers for Disease Control and Prevention (CDC) at (770) 488-7655.

This letter will allow you to begin marketing your device as described in your 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.

If you desire specific advice for your device on our labeling regulation (21 CFR Part 801 and additionally 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4588. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its internet address "http://www.fda.gov/cdrh/dsmamain.html".

Sincerely yours,
Steven Gutman

Steven I. Gutman, M.D., M.B.A. Director Division of Clinical Laboratory Devices Office of Device Evaluation Center for Devices and Radiological Health

Enclosure

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Page 1 __ 01 _1

i 10(k) Number (if known):

Device Name:

Indications For Use:

Osteomark is a urinary assay that provides a quantitative measure of the Ostecmark is a urinary assay that provides of type I collagen (NTx) as an excretion of cross-linked N-celopeperation Revels of winds of windscate elevated human bone resorption. Masurement of NT is intenced for use in: rated human bone resorption. Measurement of this is and into A. . resorptive therapy in postmenopausal women

Therapeutic monitoring of: B.

antiresorptive therapies in postmenopausal women 1.
antiresorptive therapies in individuals diagnosed uth osteoporosis
antiresorptive therapies in individuals diagnosed uith 2aget's disease 2.
antiresorptive therapies in individuals diagnosed with ?aget's disease 3. of bone
estrogen-suppressing therapies বঁ

Identifying the probability for a decrease in bone mineral ບ້ density after one year in postmenopausal women receiving calcium density arrer one year in pourment persuith hormonal antiresorptive therapy.

The measurement range of Osteomark is 20 to 3000 nM Bone Collagen Equivalents (BCE).

(PLEASE DO NOT WRITE BELOW THIS LINE - CONTINUE ON ANOTHER PAGE IF NEEDED)

Concurrence of CDRH, Office of Device Evaluation (ODE)
Company of Children Company of Children Company of Children

(Division Sign-Off)
Division of Clinical Laboratory Devices
510(k) Number. K980518

Prescription Use Per 21 CER 801.109)

Over-The-Counter Use

(Optional Formal 1-2-96)

Regulation Number and Section

§ 862.1400 Hydroxyproline test system.

(a)
Identification. A hydroxyproline test system is a device intended to measure the amino acid hydroxyproline in urine. Hydroxyproline measurements are used in the diagnosis and treatment of various collagen (connective tissue) diseases, bone disease such as Paget's disease, and endocrine disorders such as hyperparathyroidism and hyperthyroidism.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 862.9.