(290 days)
The IDS iSYS 25-Hydroxy Vitamin DS Assay (IDS-iSYS 250HD*) is intended for the quantitative determination of 25-hydroxyvitamin D (25OHD) and other hydroxylated metabolites in human serum on the IDS iSYS Multi-Discipline Automated System. Results are to be used in conjunction with other clinical and laboratory data to assist the clinician in the assessment of vitamin D sufficiency in an adult population.
The IDS-iSYS 25-Hydroxy Vitamin DS (250HDS) Control Set is used for quality control of the IDSiSYS 25-Hydroxy Vitamin DS assay on the IDS-iSYS Multi-Discipline Automated System.
The IDS-iSYS 25-Hydroxy Vitamin DS assay consists of a reagent cartridge and one set of calibrators (Calibrators A & B or CAL A & CAL B). The reagent cartridge contains multiple reagents: MPV1 (Magnetic particles coated with 25-OH D in a phosphate buffer containing methanol with sodium azide as preservative), CONJ (Anti- 25-OH D sheep polyclonal antibody labelled with an acridinium ester derivative, in buffer containing bovine, sheep, rabbit and mouse proteins with sodium azide as preservative), NaOH (Sodium hydroxide solution <0.5 M), and BUF (Assay buffer containing proprietary displacing compounds, methanol, and sodium azide as preservative). Calibrators A and B contain horse serum in a buffer matrix with two defined concentrations of 25-OH D and sodium azide as a preservative. The IDS-iSYS 25-Hydroxy Vitamin DS Control Set contains horse serum in a buffer matrix with three defined concentrations of 25-OH D and sodium azide as a preservative.
This is an analysis of a 510(k) summary for the IDS-iSYS 25-Hydroxy Vitamin Dˢ Assay and IDS-iSYS 25-Hydroxy Vitamin Dˢ Control Set.
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are generally established by internal specifications of the manufacturer, often guided by CLSI (Clinical and Laboratory Standards Institute) guidelines or regulatory precedents. The document presents the reported performance without explicitly stating pre-defined acceptance criteria for each measurement, but rather implies acceptability by presenting results typically expected for such assays. For some sections, such as precision/reproducibility and interference, the acceptable range is mentioned within the text (e.g., ±10% bias for interference).
| Performance Characteristic | Acceptance Criteria (Implied/Stated) | Reported Device Performance (IDS-iSYS 25-Hydroxy Vitamin Dˢ) |
|---|---|---|
| Precision/Reproducibility (Total CV%) | No explicit overall criterion, typically <10-15% for clinical assays. | Serum 1 (13.2 ng/mL): 10.6% |
| (Based on CLSI EP5 A2) | Serum 2 (27.2 ng/mL): 9.0% | |
| Serum 3 (38.9 ng/mL): 9.1% | ||
| Serum 4 (54.5 ng/mL): 9.1% | ||
| Serum 5 (77.2 ng/mL): 8.5% | ||
| Serum 6 (119.9 ng/mL): 7.2% | ||
| Linearity (R²) | Typically ≥ 0.99 for good linearity. | R² = 1.00 |
| Reportable Range | Defined by linearity study. | 7-125 ng/mL |
| Limit of Blank (LoB) | As determined by CLSI EP-17A. | 0.6 ng/mL |
| Limit of Detection (LoD) | As determined by CLSI EP-17A. | 2.6 ng/mL |
| Limit of Quantitation (LoQ) | As determined by CLSI EP-17A (at 20% precision CV). | 7.0 ng/mL |
| Analytical Specificity (Cross-reactivity - Endogenous) | Percentage cross-reactivity with specified metabolites. | 25(OH)D3: 97% |
| 25(OH)D2: 120% | ||
| 24,25(OH)2D3: 124% | ||
| Analytical Specificity (Cross-reactivity - Exogenous) | Percentage cross-reactivity with specified metabolites. | 3-epi-25(OH)D3: 1% |
| 3-epi-25(OH)D2: 1% | ||
| 1,25-(OH)2 D3: -23% | ||
| 1,25-(OH)2 D2: 9% | ||
| Vitamin D3: 0% | ||
| Vitamin D2: 0% | ||
| Paricalcitol: 0% | ||
| Interference (Bias %) | < ±10% bias the control sample to the test sample. | Triglycerides: -6% & -5% (at 500mg/dL) |
| Bilirubin, conjugated: 9.2% & 6.4% (at 30mg/dL) | ||
| Haemoglobin: -8% & -2% (at 40mg/dL) | ||
| Biotin: 1% & -3% (at 300nmol/L) | ||
| HAMA: -5% & -2% (at 500ng/mL) | ||
| Red Blood Cells: -10% & -2% (at 0.2%) | ||
| Vitamin DBP: 0% & 0% (at 2000ng/mL) | ||
| Method Comparison (vs. ID-LC-MS/MS RMP) | Slope typically close to 1, intercept close to 0, high R or r. | Passing-Bablok: Slope = 0.95 (CI: 0.86 to 1.04), Intercept = 0.80 ng/mL (CI: -1.32 to 3.08 ng/mL) |
| Deming: Slope = 0.94 (CI: 0.86 to 1.01), Intercept = 1.34 ng/mL (CI: -0.78 to 3.45 ng/mL) | ||
| Pearson r: 0.925 | ||
| Method Comparison (vs. Predicate device) | Slope typically close to 1, intercept close to 0, high R or r. | Passing-Bablok: Slope = 0.96 (CI: 0.91 to 1.01), Intercept = 1.1 ng/mL (CI: -0.3 to 2.3 ng/mL) |
| Correlation Coefficient, r: 0.94 |
2. Sample Sizes Used for the Test Set and Data Provenance
- Precision/Reproducibility: 6 serum samples, 80 measurements each (total = 480 measurements across 3 lots, 2 internal replicates, 2 external replicates, 20 days, 3 analyzers). Data provenance: Not explicitly stated, but typically internal studies.
- Linearity/Assay Reportable Range: 11 concentration levels from a high and low serum sample dilution, each assayed in duplicate from one manufacturing batch (total 22 concentration levels). Data provenance: Not explicitly stated, typically internal studies.
- Detection Limit:
- LoB: Zero calibrator assayed as 10 replicates over 10 assays on 10 separate days (total of 100 measurements).
- LoD: 10 samples (native and/or diluted) with very low vitamin D concentrations, in duplicate over 12 assays spanning multiple days (total of 240 data points).
- LoQ: 13 low samples (native and/or diluted) in duplicate over 7 individual assays spanning multiple days (total of 182 data points).
Data provenance for all detection limits: Not explicitly stated, typically internal studies.
- Analytical Specificity (Cross-reactivity): Not explicitly stated numbers of samples per cross-reactant, but uses vitamin D serum samples, some spiked. Data provenance: Not explicitly stated, typically internal studies.
- Interference: Not explicitly stated numbers of samples per interfering agent, but uses test vs. control samples, and in one case, 26 measurements for each condition. Data provenance: Not explicitly stated, typically internal studies.
- Method Comparison with Predicate Device (vs. ID-LC-MS/MS RMP): 99 samples. Data provenance: Not explicitly stated, but implies connection to CDC VDSP program for traceability.
- Method Comparison with Internal Predicate Device: 283 European-sourced serum samples. Data provenance: European, retrospective.
- Expected Values/Reference Range: 275 apparently healthy adults (light skin and dark skin, male and female, aged 21-77 years) from geographically diverse regions of the United States. Data provenance: Prospective, United States.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
For this in vitro diagnostic device (IVD), the "ground truth" is typically established by reference methods or accepted techniques for measuring the analyte. No human expert "adjudication" in the sense of image review is performed.
- For Traceability/Standardization: The device is traceable to the isotope dilution-liquid chromatography/tandem mass spectrometry (ID-LC-MS/MS) 25(OH)D Reference Method Procedure (RMP) which was used in assigning the target value for the VDSP samples. The ID-LC-MS/MS RMP is traceable to the National Institute of Standards and Technology Standard Reference Material (SRM) 2972. This is considered the reference standard, not "expert concensus" in this context.
- For Method Comparison with Predicate Device (vs. ID-LC-MS/MS RMP): The ID-LC-MS/MS RMP serves as the reference method and thus the "ground truth" in this comparison.
4. Adjudication Method for the Test Set
Not applicable. This is an IVD device, and the ground truth is established by chemical reference methods and measurements, not by human expert adjudication of interpretations.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This device is an in vitro diagnostic assay that directly quantifies an analyte in serum, not an imaging device requiring human interpretation, which is where MRMC studies are typically employed. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply here.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
Yes, the studies presented (precision, linearity, detection limits, specificity, method comparisons) evaluate the standalone performance of the IDS-iSYS 25-Hydroxy Vitamin Dˢ Assay. This device is an automated system designed to provide quantitative results directly from serum samples without direct human interpretation of the assay's output for diagnosis, beyond basic quality control and clinical interpretation of the quantitative value.
7. The Type of Ground Truth Used
The ground truth for the analytical performance studies (e.g., linearity, detection limit, cross-reactivity, interference) is established by the design of the experiments, using known concentrations of analytes, spiked samples, or reference materials.
For the method comparison studies, the ground truth is:
- ID-LC-MS/MS RMP (Reference Method Procedure): This is considered the gold standard or highly accurate reference method for 25(OH)D measurement, traceable to NIST SRM 2972.
- The currently marketed IDS-iSYS 25-Hydroxy Vitamin D (K091849) predicate device: This device's results are used as a comparative "truth" to demonstrate substantial equivalence, although the new device is also aligned with the ID-LC-MS/MS RMP.
8. The Sample Size for the Training Set
The document does not explicitly delineate a separate "training set" in the context of machine learning. For IVD devices like this, method development and optimization phases involve extensive testing with various samples, which could be considered analogous to a training process, but it's not typically formally described as such.
- Calibrator Traceability and Value Assignment: Master calibrators and kit calibrators are developed using stock solutions, and their values are adjusted based on results from running calibrators in multiple assays (minimum of 20 assay runs for kit calibrators) and multiple analyzers. Final values are adjusted for batch-to-batch consistency and alignment to the CDC VDSP program based on multiple correlation assays of an "established patient library panel". The size of this patient library panel is not specified.
9. How the Ground Truth for the Training Set Was Established
As noted above, a formal "training set" with ground truth in the machine learning sense is not explicitly described. However, the development and calibration of the assay involve:
- Traceability to U.V. quantification and then ID-LC-MS/MS RMP:
- Internal stock solutions are prepared, and their potency is initially based on absorbance at 264nm of an ethanolic 25D solution.
- Master calibrators are prepared, and their final value assignment is based on extensive testing against the assay itself (running them in multiple assays on multiple analyzers).
- The kit calibrators are tested as unknowns in a minimum of 20 assay runs calibrated with master calibrators, and values are adjusted to ensure consistency and alignment to the CDC VDSP program based on multiple correlation assays of an established patient library panel. This patient library panel's "ground truth" would have been established by the ID-LC-MS/MS RMP.
In summary, for this IVD, the ground truth primarily relies on established analytical standards and reference methods (ID-LC-MS/MS, NIST SRMs), rather than expert consensus or pathology reports. The studies demonstrate the assay's analytical performance and its comparability to both the ID-LC-MS/MS RMP and a predicate device.
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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
December 19, 2014
IMMUNODIAGNOSTIC SYSTEMS LTD. MICK HENDERSON, RA OFFICER 10 DIDCOT WAY, BOLDON BUSINESS PARK BOLDON, TYNE & WEAR NE35 9PD UNITED KINGDOM
Re: K140554
Trade/Device Name: IDS-iSYS 25-Hydroxy Vitamin DS Assay IDS-iSYS 25-Hydroxy Vitamin D8 Control Set Regulation Number: 21 CFR 862.1825 Regulation Name: Vitamin D test system Regulatory Class: II Product Code: MRG, JJX Dated: November 10, 2014 Received: November 10, 2014
Dear Mr. Mick Henderson:
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,
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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DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration
Indications for Use
Form Approved: OMB No.0910-0120 Expiration Date: January 31, 2017 See PRA Statement below.
510(k) Number (if known) K140554
Device Name IDS-iSYS 25-Hydroxy Vitamin DS 1DS-iSYS 25-Hydroxy Vitamin DS Control Set
Indications for Use (Describe)
The IDS iSYS 25-Hydroxy Vitamin DS Assay (IDS-iSYS 250HD*) is intended for the quantitative determination of 25-hydroxyvitamin D (25OHD) and other hydroxylated metabolites in human serum on the IDS iSYS Multi-Discipline Automated System. Results are to be used in conjunction with other clinical and laboratory data to assist the clinician in the assessment of vitamin D sufficiency in an adult population.
The IDS-iSYS 25-Hydroxy Vitamin DS (250HDS) Control Set is used for quality control of the IDSiSYS 25-Hydroxy Vitamin DS assay on the IDS-iSYS Multi-Discipline Automated System.
| 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
| 510k Number | K140554 |
|---|---|
| Introduction | According to the requirements of 21CFR807.92, the followinginformation provides sufficient detail to understand the basis for adetermination of substantial equivalence. |
| Submitter | Immunodiagnostic Systems Limited10 Didcot WayBoldon Business ParkBoldonTyne and WearNE35 9PDUnited KingdomContact Person: Mick HendersonPhone: +44 191 5190660Fax: +44 191 5190760Email: mick.henderson@idsplc.comSecondary Contact: Mr. R. PrebulaHogan Lovells US LLP,Columbia Square,555 Thirteenth Street, NW,Washington DC20004WashingtonPhone: (202)637 6548Fax: (202)637 5910Email: randy.prebula@hoganlovells.comDate prepared: 17, December 2014 |
| Device Name | Proprietary names: IDS-iSYS 25-Hydroxy Vitamin DSIDS-iSYS 25-Hydroxy Vitamin DS Control Set |
| Common names: As above | |
| Classification: 21CFR862.1825 Vitamin D Test System,Class II21CFR862.1660 Quality Control Material(Assayed and Unassayed),Class I, reserved | |
| Product Code: MRG |
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| Predicate Device | The IDS-iSYS 25-Hydroxy Vitamin DS is substantially equivalent toother products in commercial distribution intended for similar use. Weclaim equivalency to the currently marketed IDS-iSYS 25-HydroxyVitamin D (K091849). |
|---|---|
| Device Description | The IDS-iSYS 25-Hydroxy Vitamin DS assay consists of a reagentcartridge and one set of calibrators (Calibrators A & B or CAL A &CAL B). The reagent cartridge contains multiple reagents: MPV1(Magnetic particles coated with 25-OH D in a phosphate buffercontaining methanol with sodium azide as preservative), CONJ (Anti-25-OH D sheep polyclonal antibody labelled with an acridinium esterderivative, in buffer containing bovine, sheep, rabbit and mouseproteins with sodium azide as preservative), NaOH (Sodium hydroxidesolution <0.5 M), and BUF (Assay buffer containing proprietarydisplacing compounds, methanol, and sodium azide as preservative). |
| Calibrators A and B contain horse serum in a buffer matrix with twodefined concentrations of 25-OH D and sodium azide as a preservative.The IDS-iSYS 25-Hydroxy Vitamin DS Control Set contains horseserum in a buffer matrix with three defined concentrations of 25-OH Dand sodium azide as a preservative. | |
| Indications for Use | The IDS-iSYS 25-Hydroxy Vitamin DS assay (IDS-iSYS 25OHDS ) isintended for the quantitative determination of 25-hydroxyvitamin D(25OH D) and other hydroxylated metabolites in human serum on theIDS-iSYS Multi-Discipline Automated System. Results are to be usedin conjunction with other clinical and laboratory data to assist theclinician in the assessment of vitamin D sufficiency in an adultpopulation.The IDS-iSYS 25-Hydroxy Vitamin DS (25OHDS) Control Set is usedfor quality control of the IDS-iSYS 25-Hydroxy Vitamin DS assay onthe IDS-iSYS Multi-Discipline Automated System. |
| Conditions for use: | For in vitro diagnostic use only.Rx Only: |
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Comparison Tables
Similarities compared to the chosen predicate device (K091849)
| Performance | IDS-iSYS 25-Hydroxy VitaminD AssayPredicate device (K091849) | IDS-iSYS 25-Hydroxy VitaminDˢCandidate device |
|---|---|---|
| Intended Use | Quantitative determination of 25-Hydroxy Vitamin D and otherhydroxylated metabolites inhuman serum. | Same |
| Indications for use | Results are to be used inconjunction with other clinicaland laboratory data to assist theclinician in the assessment ofvitamin D sufficiency in an adultpopulation. | Same |
| Analyte | 25-Hydroxy Vitamin D (25-OHD) | Same |
| Calibrator matrix | Equine serum buffer matrix withtwo defined concentrations of 25-OH D and sodium azide as apreservative. | Same |
| Sample matrix(primary tube type) | Human Serum | Same |
| Reagent storage | 2-8 °C | Same |
| Sample preparation(pre-treatment) | Performed on-board the analyzer | Same |
| Sample volume | 10μL | Same |
| Method of detection(Test methodology) | Chemiluminescent immunoassayusing magnetic-particle solidphase and acridinium label | Same |
| Automation | Fully automated assay | Same |
| Kit reagentcomponents | Reagent cartridge (1 vial each ofMPV1, CONJ, NaOH & BUF),two concentration levels ofcalibrators (A&B) (1 vial of each)& a mini CD | Same |
| Control Kitcomponents | Three concentration levels ofcontrols (3 vials of each) & amini CD | Same |
| Calibrationprocedure | User-initiated 2 point calibrationto adjust the batch related mastercurve. The system stores thecalibration for the intervalspecified in the kit IFU. | Same |
| Quality Control | Requires three buffer basedcontrols to validate the calibration | Same |
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Kit Controls:
| Performance | IDS-iSYS 25-Hydroxy Vitamin D Control SetPredicate (K091849) | IDS-iSYS 25-Hydroxy Vitamin DS Control Set |
|---|---|---|
| Intended Use | The quality control of the assay on the IDS-iSYS. | Same |
| Control matrix | Equine serum buffer matrix with three defined concentrations of 25-OH D and sodium azide as a preservative. | Same |
| Control Kitcomponents | Three concentration levels of controls (3 vials of each) & a mini CD | Same |
| Quality Control | Requires three buffer based controls to validate the calibration | Same |
| Stability | After opening at 2 - 8 °C: To the expiry dateOn board the analyzer: 2.5 hours | Same |
| Reagent storage | 2-8 °C | Same |
Differences compared to the chosen (FDA cleared; marketed) predicate device
| Performance | Predicate device | Candidate device |
|---|---|---|
| Kit reagentcomponentvolumes | Reagent cartridge (1 vial each):MPV1 (2.6mL), CONJ (7.1mL),NaOH (5.2mL) & BUF (26.0mL) | Reagent cartridge (1 vial each):MPV1 (2.0mL), CONJ (10.1mL),NaOH (5.2mL) & BUF (26.0mL) |
| Antibodies | Anti-25 OH D Sheep Polyclonal IgG | Same, but with a different sourceof antibody pool. |
| Traceability/Standardization | Traceable to U.V. quantification. | Traceable to the isotope dilution-liquid chromatography/tandemmass spectrometry (ID-LC-/MS/MS) 25(OH)D ReferenceMethod Procedure (RMP) whichwas used in assigning the targetvalue for the VDSP samples.The ID-LC-MS/MS RMP is |
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| traceable to the National Instituteof Standards and TechnologyStandard Reference Material(SRM) 2972. | ||
|---|---|---|
| Calibration interval | 7 days | 14 days |
| Range of assay | 6 - 126ng/mL | 7 - 125ng/mL |
| Sensitivity | LoB: 1.8 ng/mL | LoB: 0.6 ng/mL |
| LoD: 3.6 ng/mL | LoD: 2.6 ng/mL | |
| LoQ: 6.2 ng/mL | LoQ: 7.0 ng/mL | |
| Reference range | Non-parametric reference interval: 7.9- 57.8ng/mL (n=150) | Non-parametric referenceinterval: 12.7 – 64.2ng/mL(n=275) |
| Assay Duration | 38 minutes | 36 minutes |
| On board theanalyzer reagentstability | 7 days | 21 days |
| In use (afteropening at 2-8°C)reagent stability | 14 days | 21 days |
Performance Characteristics (if/when applicable):
-
- Analytical performance:
- a. Precision/Reproducibility:
A study was performed in accordance with CLSI EP5 A2 where six (6) serum samples (ranging from 12.0ng/mL to 116.5ng/mL) were assayed using three (3) lots of reagents in duplicate (n=2) twice per day for 20 days on three (3) analyzers.
Representative LOT
| Sample | n | mean | Within-run | Total | ||
|---|---|---|---|---|---|---|
| (ng/mL) | SD | CV% | SD | CV% | ||
| Serum 1 | 80 | 13.2 | 0.8 | 6.4% | 1.4 | 10.6% |
| Serum 2 | 80 | 27.2 | 1.5 | 5.4% | 2.5 | 9.0% |
| Serum 3 | 80 | 38.9 | 2.3 | 5.8% | 3.5 | 9.1% |
| Serum 4 | 80 | 54.5 | 3.2 | 5.8% | 5.0 | 9.1% |
| Serum 5 | 80 | 77.2 | 4.0 | 5.2% | 6.6 | 8.5% |
| Serum 6 | 80 | 119.9 | 6.1 | 5.1% | 8.6 | 7.2% |
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b. Linearity/assay reportable range:
Linearity was evaluated based on CLSI EP-6A, "Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach". In the linearity study, samples were prepared by diluting a high serum sample with a low serum sample to obtain eleven (11) concentration levels across the measuring range. One study was performed with one manufacturing batch resulting in a total of 22 concentration levels ranging from 5.8ng/mL to 152.9ng/mL. Each concentration level was assayed in duplicate, and the resulting mean concentrations were compared to predicted concentrations.
The resulting linear regression equation was y = 0.96x + 2.1ng/mL, R2 = 1.00
The reportable range of the assay is 7-125ng/mL.
- c. Traceability, Stability, Expected values (controls, calibrators, or methods):
Calibrator traceability and value assignment
An internal stock solution is prepared by reconstituting a vial of 25hydroxyvitamin D3 with ethanol and adding this to horse serum. The potency assigned to the stock solution is nominally based on the absorbance at 264nm of the ethanolic 25D solution prior to addition to the serum. A molar extinction coefficient of 18,200 is used to calculate the concentration from the absorbance value. This stock solution is used to prepare master calibrators, whose final value assignment is based on results from running the calibrators in multiple assays on multiple analyzers.
Kit calibrators are lot specific for each assay kit. Master calibrators and kit calibrators A and B are prepared gravimetrically from the stock solution or an intermediate stock solution. For value assignment, the kit calibrators are tested as unknowns in a minimum of 20 assay runs using one analyzer. Each run is calibrated using master calibrators. The values are then adjusted to ensure batch-to-batch consistency where necessary, and to facilitate the alignment to the CDC VDSP program, based on multiple correlation assays of an established patient library panel. The final assigned values obtained for the kit calibrators are verified on three additional analyzers. The values must fall within specified acceptable ranges.
The assay is traceable to the isotope dilution-liguid chromatography/tandem mass spectrometry (ID-LC-/MS/MS) 25(OH)D Reference Method Procedure (RMP) which was used in assigning the target value for the VDSP samples.
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The ID-LC-MS/MS RMP is traceable to the National Institute of Standards and Technology Standard Reference Material (SRM) 2972.
Stability
As there has been no change to the kit calibrators or kit controls formulation, design or intended use, the cleared IDS-iSYS 25-Hydroxy Vitamin D product (K091849) should be referred to for the relevant performance and stability details. The calibrator and control shelf-life and open-vial stability testing protocols and acceptance criteria were described and found to be adequate. Once opened calibrators and controls are stable for up to 2.5 hours on board the analyzer. Current accelerated shelf life studies support the assigned sixmonth shelf life, with real-time studies on-going.
d. Detection limit:
The Limit of Blank (LoB), Limit of Detection (LoD) and Limit of Quantification (LoQ) studies were performed according to CLSI EP-17A.
To establish the Limit of Blank (LoB), the zero calibrator was assayed as 10 replicates over 10 assays on 10 separate days giving a total of 100 measurements. The Limit of Blank was determined by calculating the concentration corresponding to the mean zero calibrator minus two standard deviations from the 4PL calibration curve. The LoB claim is 0.6ng/mL.
The Limit of Detection (LoD) study was performed by assaying 10 samples (native and/or diluted) with very low vitamin D concentrations (ranging from 1.9ng/mL to 8.0ng/mL) in duplicate over 12 assays spanning multiple days giving a total of 240 data points. The LoD claim is 2.6ng/mL.
The Limit of Quantification (LoQ) was determined by measuring 13 low samples (native and /or diluted) in a concentration range of 2.8 - 24.6ng/mL in duplicate over 7 individual assays spanning multiple days giving 182 data points. The LoQ claim is 7.0ng/mL and was calculated by interpolating the concentration of the analyte from the regression curve at 20% precision C.V.
e. Analytical specificity:
Cross-reactivity by adding endogenous 25(OH) vitamin D metabolite to serum samples: Endogenous 25(OH) vitamin D metabolites were spiked into vitamin D serum samples and analyzed with the IDS-iSYS 25-Hydroxy Vitamin Do assay. The value of un-spiked sample and spike concentration were determined by LC-MS/MS 25(OH)D method. The spiked sample was measured with the IDS-iSYS 25-Hydroxy Vitamin De assay. The % cross-reactivity was calculated based on following equation:
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Mean conc. of spiked sample – mean conc. of unspiked sample_ x100% Spiked concentration
| CrossReactant | Spike Conc.(ng/mL) | Un-spikedsamplevalue(ng/mL) | Spikedsamplevalue(ng/mL) | % CrossReactivity | Mean %CrossReactivity |
|---|---|---|---|---|---|
| 25(OH)D3 | 10.0 | 20.2 | 29.2 | 90% | 97% |
| 20.0 | 14.3 | 35.1 | 104% | ||
| 25(OH)D2 | 10.0 | 16.1 | 28.5 | 124% | 120% |
| 20.0 | 11.1 | 34.4 | 117% | ||
| 24,25(OH)2D3 | 5.0 | 66.2 | 72.4 | 124% | 124% |
- b. Cross-reactivity by adding exogenous synthetic 25(OH) vitamin D metabolite to serum samples: Exogenous synthetic 25(OH) vitamin D metabolites were spiked into vitamin D serum samples. The un-spiked and spiked samples were measured with the IDS-iSYS 25- Hydroxy Vitamin Ds assay. The % cross reactivity was calculated based on the following equation:
Mean conc. of spiked sample - mean conc. of unspiked sample _ x100% Spiked concentration
| Cross Reactant | Spikedconc.(ng/mL) | SampleNativeconc.(ng/mL) | % Crossreactivity | Mean %Crossreactivity |
|---|---|---|---|---|
| 3-epi-25(OH)D3 | 100.0 | 9.4 | 0% | |
| 100.0 | 36.4 | 3% | 1% | |
| 3-epi-25(OH)D2 | 100.0 | 8.6 | 0% | |
| 100.0 | 33.4 | 2% | 1% | |
| 1,25-(OH)2 D3 | 2.0 | 7.1 | 19% | |
| 2.0 | 31.2 | -65% | -23% | |
| 1,25-(OH)2 D2 | 20.0 | 8.6 | 13% | |
| 20.0 | 37.9 | 5% | 9% | |
| Vitamin D3(Cholecalciferol) | 1000.0 | 6.9 | 0% | |
| (Cholecalciferol) | 1000.0 | 30.8 | 0% | 0% |
| Vitamin D2(Ergocalciferol) | 100.0 | 7.4 | 1% | |
| (Ergocalciferol) | 100.0 | 37.3 | -2% | 0% |
| Paricalcitol | 100.0 | 8.2 | 0% | |
| 100.0 | 33.4 | 2.9% | 0% |
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The following potentially interfering endogenous substances listed within the package insert do not interfere in the IDS-iSYS 25-Hydroxy Vitamin De assay when the concentrations presented in the following table are below the stated threshold, using a criterion of ±10% bias of the control sample to the test sample. Rheumatoid Factor was assessed using a recovery study with two 'normal' samples; the specification is based on recovery criteria of 90 - 110%. RF does not show significant interference up to 1500 IU/L tested. To evaluate potential lipid interference a natural specimen with 500mg/dL lipid concentration was obtained. A portion was delipidated and assayed along with the same unaltered specimen n=23 in the IDS-iSYS 25-Hydroxy Vitamin De assay.
| PotentiallyInterfering Agent | ThresholdConcentration | Sample 25OHDConcentration | n | Bias (Test vs.ControlSample) |
|---|---|---|---|---|
| Triglycerides | 500mg/dL | 50.0ng/mL & 87.9ng/mL | 26 & 26 | -6% & -5% |
| Bilirubin,conjugated | 30mg/dL | 18.0ng/mL & 65.7ng/mL | 26 & 26 | 9.2% & 6.4% |
| Haemoglobin | 40mg/dL | 19.2ng/mL & 71.7ng/mL | 26 & 26 | -8% & -2% |
| Biotin | 300nmol/L | 17.0ng/mL & 66.2ng/mL | 26 & 26 | 1% & -3% |
| HAMA | 500ng/mL | 18.2ng/mL & 72.8ng/mL | 25 & 26 | -5% & -2% |
| Red Blood Cells | 0.2% | 15.5ng/mL & 65.8ng/mL | 26 & 26 | -10% & -2% |
| Vitamin DBP | 2000ng/mL | 18.9ng/mL & 76.0ng/mL | 24 & 26 | 0% & 0% |
The package insert also states that the presence of haemoglobin at concentrations >40mg/dL might lead to falsely depressed values. Do not use hemolyzed samples.
- Assay cut-off: f.
Not applicable
2. Comparison studies:
a. Method comparison with predicate device:
A method comparison study was performed to demonstrate the accuracy of the newly aligned assay. With the aligned assay calibration parameters, 99 samples in the range of 9.0ng/mL to 98.6ng/mL, by ID-LC-MS/MS RMP, were used to assess the IDSiSYS 25-Hydroxy Vitamin D assay traceability against the ID-LC-MS/MS RMP.
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The relationship between the IDS-iSYS (y) and the ID-LC-MS/MS RMP (x) is described using Passing-Bablok regression & Deming regression:
Passing Bablok regression: IDS-iSYS = 0.95 x (ID-LC-MS/MS RMP)+ 0.80ng/mL 95 % CI of the slope: 0.86 to 1.04 95 % CI of the intercept: -1.32 to 3.08ng/mL
Deming regression: IDS-iSYS = 0.94 x (ID-LC-MS/MS RMP)+1.34ng/mL 95 % CI of the slope: 0.86 to 1.01 95 % CI of the intercept: -0.78 to 3.45ng/mL
Pearson correlation coefficient, r: 0.925
In addition, the following method comparison study was performed to characterize the comparison of the newly aligned IDS-iSYS 25-Hydroxy Vitamin De assay to the unaligned IDS-iSYS 25-Hydroxy Vitamin D assay:
Method comparison studies were performed following CLSI EP9-A2. An internal method comparison study was performed with a total of 283 European-sourced serum samples tested in singlicate on the IDS-iSYS 25-Hydroxy Vitamin D Assay and the predicate (the IDS-iSYS 25-Hydroxy Vitamin D Assay). Samples spanned the assay range with values from 7.3 -115.1 ng/mL (candidate values).
Passing-Bablok regression analysis was performed to produce a summary of results for each study, as shown below.
| Passing Bablok | y = 0.96x + 1.1ng/mL |
|---|---|
| Slope, 95% Confidence Interval | 0.91 to 1.01 |
| Intercept, 95% Confidence Interval | -0.3 to 2.3ng/mL |
| Correlation Coefficient, r | 0.94 |
| n | 283 |
| Range | 7.3 to 115.1 ng/mL |
Internal Study:
-
a. Matrix comparison:
Not applicable. Only serum may be used. -
- Expected values/Reference range:
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An expected values study performed according to the non-parametric method in CLSI protocol C28-A2.
Samples from 275 apparently healthy light skin and dark skin male and female adults living in the United States, aged 21 to 77 years, in geographical diverse regions of the United States to represent a broad spectrum of UV light exposure in the intended population were assayed in the IDS-iSYS 25-Hydroxy Vitamin DS Assay.
The 95% reference interval was calculated by a non-parametric method following C28-A2. The following range was obtained:
Normal Adults 12.7 - 64.2ng/mL (n=275)
| n | Observed Sample Range | Median | |
|---|---|---|---|
| Non-supplemented | 220 | 11.9 - 91.9ng/mL | 31.8ng/mL |
| Northern US | 116 | 11.9 - 55.4ng/mL | 29.7ng/mL |
| Southern US | 104 | 14.3 - 91.9ng/mL | 36.3ng/mL |
| Supplemented | 55 | 8.2 - 83.8ng/mL | 35.3ng/mL |
| Overall | 275 | 8.2 - 91.9ng/mL | 32.5ng/mL |
Observed sample ranges were:
The package insert states that there is no universal agreement on the optimal concentration of 250HD. Ranges should be based on clinical decision values that apply to both sexes of all ages rather than population based reference ranges for 25OHD.
Conclusion:
The IDS-iSYS 25-Hydroxy Vitamin DS and IDS-iSYS 25-Hydroxy Vitamin DS Control Set data presented and provided is complete and supports the basis for substantial equivalence to the predicate device.
§ 862.1825 Vitamin D test system.
(a)
Identification. A vitamin D test system is a device intended for use in clinical laboratories for the quantitative determination of 25-hydroxyvitamin D (25-OH-D) and other hydroxylated metabolites of vitamin D in serum or plasma to be used in the assessment of vitamin D sufficiency.(b)
Classification. Class II (special controls). Vitamin D test systems must comply with the following special controls:(1) Labeling in conformance with 21 CFR 809.10 and
(2) Compliance with existing standards of the National Committee on Clinical Laboratory Standards.