VITROS Immunodiagnostic Products NT-proBNP II Reagent Pack
Device Facts
| Record ID | K201312 |
|---|---|
| Device Name | VITROS Immunodiagnostic Products NT-proBNP II Reagent Pack |
| Applicant | Ortho Clinical Diagnostics |
| Product Code | NBC · Clinical Chemistry |
| Decision Date | Oct 4, 2021 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 862.1117 |
| Device Class | Class 2 |
Intended Use
For the quantitative measurement of N-terminal pro Brain Natriuretic Peptide (NT-proBNP) in human serum and plasma (K2 EDTA or lithium heparin) using the VITROS 3600 Immunodiagnostic System to aid in the diagnosis of heart failure. The test can also be used in the assessment of heart failure severity in patients diagnosed with heart failure.
Device Story
VITROS NT-proBNP II assay is a quantitative sandwich immunoassay performed on the VITROS 3600 Immunodiagnostic System. Input: human serum or plasma (K2 EDTA or lithium heparin). Principle: one-step immunometric bridging assay; patient sample dispensed into antibody-coated well with HRP-labeled conjugate and biotinylated capture antibody; bound HRP conjugate measured via luminescent reaction (luminogenic substrate oxidation). Output: light signal proportional to NT-proBNP concentration (pg/mL). Used in clinical laboratories; operated by trained personnel. Results interpreted against age-dependent cutoffs (ED setting) or a single cutoff (outpatient setting) to aid heart failure diagnosis and severity assessment. Benefits: provides objective biomarker data to assist clinicians in diagnosing heart failure and assessing disease severity, potentially improving diagnostic accuracy and patient management.
Clinical Evidence
Clinical performance was established in a multi-center prospective study of 2,200 ED subjects and 777 outpatient subjects. Primary endpoints included AUC for heart failure diagnosis and correlation with NYHA functional classification. AUC for ED subjects ranged from 0.904 to 0.954 across subgroups. The test demonstrated a statistically significant relationship between NT-proBNP levels and NYHA class (p < 0.0001).
Technological Characteristics
Sandwich immunoassay; mouse monoclonal anti-NT-proBNP antibody coated wells; HRP-conjugated sheep monoclonal anti-NT-proBNP antibody; luminescent detection; measuring range 20-30,000 pg/mL. Requires VITROS 3600 Immunodiagnostic System. Software-controlled automated processing. No specific material standards (e.g., ASTM) cited for construction.
Indications for Use
Indicated for quantitative measurement of NT-proBNP in human serum/plasma to aid in diagnosis and severity assessment of heart failure in patients aged 22 years and older.
Regulatory Classification
Identification
The B-type natriuretic peptide (BNP) test system is an in vitro diagnostic device intended to measure BNP in whole blood and plasma. Measurements of BNP are used as an aid in the diagnosis of patients with congestive heart failure.
Special Controls
*Classification.* Class II (special controls). The special control is “Class II Special Control Guidance Document for B-Type Natriuretic Peptide Premarket Notifications; Final Guidance for Industry and FDA Reviewers.”
Predicate Devices
- Roche Elecsys® proBNP II Immunoassay (K072437)
Related Devices
- K060632 — VITROS IMMUNODIAGNOSTIC PRODUCTS NT PRO-BNP REAGENT PACK,CALIBRATORS,RANGE VERIFIERS,680 2156,680 2157,680 2158 · Ortho-Clinical Diagnostics, Inc. · Jun 6, 2006
- K220265 — ADVIA Centaur® NT-proBNPII (PBNPII) · Siemens Healthcare Diagnostics, Inc. · Sep 24, 2023
Submission Summary (Full Text)
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FDA
U.S. FOOD & DRUG
ADMINISTRATION
# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
ASSAY ONLY
## I Background Information:
A 510(k) Number
K201312
B Applicant
Ortho Clinical Diagnostics
C Proprietary and Established Names
VITROS® Immunodiagnostic Products NT-proBNP II Reagent Pack
D Regulatory Information
| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| NBC | Class II | 21 CFR 862.1117 - B-Type Natriuretic Peptide Test System | CH - Clinical Chemistry |
## II Submission/Device Overview:
A Purpose for Submission:
New device.
B Measurand:
N-terminal pro Brain Natriuretic Peptide (NT-proBNP)
C Type of Test:
Quantitative sandwich immunoassay.
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
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# III Intended Use/Indications for Use:
## A Intended Use(s):
See Indications for Use below.
## B Indication(s) for Use:
For the quantitative measurement of N-terminal pro Brain Natriuretic Peptide (NT-proBNP) in human serum and plasma (K2 EDTA or lithium heparin) using the VITROS 3600 Immunodiagnostic System to aid in the diagnosis of heart failure. The test can also be used in the assessment of heart failure severity in patients diagnosed with heart failure.
## C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only
For in vitro diagnostic use only
## D Special Instrument Requirements:
VITROS 3600 Immunodiagnostic System
# IV Device/System Characteristics:
## A Device Description:
The VITROS NT-proBNP II assay (test) is performed using the VITROS® NT-proBNP II Reagent Pack and the VITROS NT-proBNP II Calibrators on the VITROS 3600 Immunodiagnostic System.
VITROS® NT-proBNP II Reagent Pack contains:
- 100 coated wells (mouse monoclonal anti-NT-proBNP antibody, 1 µg/mL).
- 8.7 mL assay reagent (buffer with sheep serum, bovine gamma globulin, bovine serum albumin, and antimicrobial agent).
- 8.7 mL conjugate reagent (HRP-conjugated sheep monoclonal anti-NT-proBNP antibody, 1 µg/mL in buffer with bovine serum albumin and antimicrobial agent).
VITROS Immunodiagnostic Products NT-proBNP II Calibrators Contents:
- 1 set of VITROS NT-proBNP II Calibrators 1, 2 and 3 (Recombinant NT-proBNP in buffer with bovine serum albumin and antimicrobial agent, 2.0 mL; nominal values 0; 450; 20,000 pg/mL.)
- Lot calibration card
- Protocol card
- 24 calibrator bar code labels (8 for each calibrator)
Materials Required but Not Provided with the reagent kit:
- VITROS immunodiagnostic products signal reagent.
- VITROS immunodiagnostic products universal wash reagent.
- VITROS immunodiagnostic products high sample diluent B.
- Quality control materials.
- VITROS immunodiagnostic products reagent pack storage box with desiccant.
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## B Principle of Operation:
The VITROS® NT-proBNP II Reagent Pack utilizes a one-step immunometric bridging assay design. A well is pushed from the pack and patient sample is dispensed into the antibody coated well. The assay reagent and the conjugate reagent are then dispensed into the well with the patient sample. NT-proBNP present in the sample binds with horseradish peroxidase (HRP)-labeled antibody conjugate which is captured by biotinylated anti-NT-proBNP capture antibody which is bound to streptavidin coated microwells. The well is incubated for 8 minutes, before unbound materials are removed by washing. The bound HRP conjugate is measured by a luminescent reaction. A reagent containing luminogenic substrate (a luminol derivative and a peracid salt) and an electron transfer agent, is added to the wells. The HRP in the bound conjugate catalyzes the oxidation of the luminol derivative, producing light. The electron transfer agent (a substituted acetanilide) increases the level of light produced and prolongs its emission. The light signals are read by the instrument. The amount of HRP conjugate bound and the corresponding signal is directly proportional to the concentration of NT-proBNP present.
## V Substantial Equivalence Information:
### A Predicate Device Name(s):
Elecsys ProBNP II
### B Predicate 510(k) Number(s):
K072437
### C Comparison with Predicate(s):
| Device & Predicate Device(s): | K201312 | K072437 |
| --- | --- | --- |
| Device Trade Name | VITROS® Immunodiagnostic Products NT-proBNP II Reagent Pack | Elecsys proBNP II |
| General Device Characteristic Similarities | | |
| Measurand | NT-proBNP | Same |
| Assay Principle | Sandwich immunoassay | Same |
| Intended Use/Indications For Use | For the quantitative measurement of N-terminal pro Brain Natriuretic Peptide (NT-proBNP) in human serum and plasma. | Same |
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| Device & Predicate Device(s): | K201312 | K072437 |
| --- | --- | --- |
| General Device Characteristic Differences | | |
| Measuring Range | 20-30,000 pg/mL | 5-35,000 pg/mL |
| Result Interpretation | For patients in the ED settings, the VITROS® NT-proBNP II Reagent Pack results should be interpreted as:
Negative: Heart failure unlikely for all patients: <300 pg/mL
Gray Zone: Indeterminate-consider other causes of NT-proBNP elevation:
Age (yrs) NT-proBNP (pg/mL)
22 - <50 ≥300 to <450
50 - <75 ≥300 to <900
≥75 ≥300 to <1800
Positive: Heart failure likely:
Age (yrs) NT-proBNP (pg/mL)
22 - <50 ≥450
50 - <75 ≥900
≥75 ≥1800
For patients in the outpatient settings, the VITROS® NT-proBNP II Reagent Pack results should be interpreted as:
<125 pg/mL: Negative -Heart failure unlikely
≥125 pg/mL: Consider heart failure as well as other sources of NT-proBNP elevation | 125 pg/mL for patients <75 years;
450 pg/mL for patients ≥75 years |
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VI Standards/Guidance Documents Referenced:
Class II Special Control Guidance Document for B-Type Natriuretic Peptide Premarket Notifications; Final Guidance for Industry and FDA Reviewers (November 30, 2000).
CLSI EP25-A. Evaluation of Stability of In Vitro Diagnostic Reagents; Approved Guideline; 2009.
CLSI EP05-A3. Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline—Third Edition; 2014.
CLSI EP17-A2. Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures; Approved Guideline – Second Edition; 2012.
CLSI EP06-A. Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; Approved Guideline; 2003.
CLSI EP07. Interference Testing in Clinical Chemistry. 3rd ed.; 2018.
CLSI EP37. Supplemental Tables for Interferent Testing in Clinical Chemistry – First Edition; 2018.
CLSI EP28-A3c. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline – Third Edition; 2010.
VII Performance Characteristics (if/when applicable):
A Analytical Performance:
1. Precision/Reproducibility:
Precision was evaluated consistent with the CLSI guideline EP05-A3. Two (2) replicates of each of 11 samples (eight human individual or serum pools and three controls) were tested on two (2) runs per day on 20 different test days (N=80). The study was performed using three (3) reagent master lots on one VITROS 3600 Immunodiagnostic System for a total of 240 measurements.
| Mean | Between Lot | | Between Day | | Between Run | | Within Run | | Total* | | N |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| pg/mL | SD | CV (%) | SD | CV (%) | SD | CV (%) | SD | CV (%) | SD | CV (%) | |
| 32 | 2.34 | 7.32 | 0.875 | 2.74 | 1.28 | 4.02 | 0.545 | 1.71 | 2.86 | 8.96 | 240 |
| 69.5† | 3.92 | 5.65 | 1.89 | 2.71 | 1.83 | 2.63 | 1.58 | 2.27 | 4.98 | 7.17 | 240 |
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| Mean | Between Lot | | Between Day | | Between Run | | Within Run | | Total* | | N |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| pg/mL | SD | CV (%) | SD | CV (%) | SD | CV (%) | SD | CV (%) | SD | CV (%) | |
| 97 | 4.65 | 4.79 | 2.65 | 2.73 | 1.89 | 1.95 | 1.56 | 1.61 | 5.89 | 6.07 | 240 |
| 369 | 9.14 | 2.48 | 6.32 | 1.71 | 7.75 | 2.10 | 4.9 | 1.33 | 14.4 | 3.91 | 240 |
| 823 | 15.9 | 1.94 | 11.6 | 1.40 | 20.5 | 2.49 | 12.5 | 1.52 | 31 | 3.77 | 240 |
| 949† | 26.6 | 2.81 | 17.5 | 1.84 | 13.9 | 1.46 | 12.2 | 1.29 | 36.8 | 3.88 | 240 |
| 1745 | 10.8 | 0.62 | 44.5 | 2.55 | 56.9 | 3.26 | 20.3 | 1.16 | 75.8 | 4.34 | 240 |
| 5859† | 75 | 1.28 | 92.1 | 1.57 | 55.4 | 0.95 | 80.3 | 1.37 | 154 | 2.62 | 240 |
| 24686 | 329 | 1.33 | 355 | 1.44 | 455 | 1.84 | 371 | 1.5 | 761 | 3.08 | 240 |
| 214 | 6.78 | 3.17 | 3.66 | 1.71 | 3.11 | 1.45 | 3.5 | 1.64 | 9.02 | 4.22 | 240 |
| 11392 | 206 | 1.81 | 145 | 1.28 | 65.2 | 0.57 | 176 | 1.54 | 314 | 2.76 | 240 |
* Total: Variability of the test incorporating factors of instrument, lot, day and run.
† Control Samples
## 2. Linearity:
The claimed measuring range is 20-30,000 pg/mL. Three (3) reagent master lots of VITROS® NT-proBNP II Reagent Packs were tested on one VITROS 3600 Immunodiagnostic System. Low and high serum sample pools were prepared and mixed to produce sample pools with 14 intermediate concentrations. A total of 16 serum samples with NT-proBNP concentrations ranging from 1.6 pg/mL to 39800 pg/mL were tested in triplicate.
The sponsor performed the analysis recommended in CLSI guideline EP06-A and the results support that the assay is linear from 20-30,000 pg/mL.
## 3. Analytical Specificity/Interference:
The VITROS® NT-proBNP II Reagent Pack was evaluated for potential interference following the CLSI EP07 A3 and CLSI EP37 (1st edition) guidelines. Several endogenous and exogenous compounds were tested with the candidate device in the presence of NT-proBNP at approximate concentrations of 125 pg/mL and 2000 pg/mL using three master reagent lots. No interference was defined as a mean percent recovery of samples containing each interference listed below within 100±10% of control. No interference was observed with the compounds up to the concentrations listed in the table below.
| Compound | Concentration | Compound | Concentration |
| --- | --- | --- | --- |
| Acetaminophen | 156 μg/mL | Ibuprofen | 21.9 mg/dL |
| Acetylcysteine | 15.0 mg/dL | Insulin | 3.12 μg/dL |
| Adrenaline (Epinephrine) | 20.0 μg/dL | Intralipid | 2.00 g/dL |
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| Compound | Concentration | Compound | Concentration |
| --- | --- | --- | --- |
| Alprazolam | 25.8 μg/dL | L-dopa (Levodopa) | 750 μg/dL |
| Amlodipine besylate | 10.5 μg/dL | Levothyroxine | 42.9 μg/dL |
| Amoxicillin | 5.40 mg/dL | Lidocaine | 1.50 mg/dL |
| Ascorbic acid | 5.25 mg/dL | Methyldopa sesquihydrate | 2.25 mg/dL |
| Atorvastatin calcium trihydrate | 162 μg/dL | Methylprednisolone | 783 μg/dL |
| Benazepril HCl | 44.0 μg/dL | Metoprolol hemitartrate | 150 μg/dL |
| Bilirubin, conjugated | 40.0 mg/dL | Metronidazole | 12.3 mg/dL |
| Bilirubin, unconjugated | 40.0 mg/dL | Molsidomine | 18.0 μg/dL |
| Biotin | 3510 ng/mL | Naproxen sodium | 39.3 mg/dL |
| Caffeine | 10.8 mg/dL | Nicardipine HCL | 46.5 μg/dL |
| Carvedilol | 43.2 μg/dL | Nifedipine | 58.8 μg/dL |
| Ceftriaxone disodium hemi(heptahydrate) | 100 mg/dL | Omeprazole | 840 μg/dL |
| Cholesterol | 400 mg/dL | Oxycodone HCl | 32.4 μg/dL |
| Clopidogrel hydrogen sulfate | 2.40 μg/dL | Phenobarbital | 69.0 mg/dL |
| Cotinine | 240 μg/dL | Phenprocoumon (Marcumar) | 1.50 mg/dL |
| Creatinine | 15.0 mg/dL | Propafenone HCL | 72.0 μg/dL |
| Cyclosporine | 180 μg/dL | Pseudoephedrine HCl | 330 μg/dL |
| Dextran | 2.40 g/dL | Rheumatoid Factor | 1500 IU/mL |
| Digitoxin | 7.50 μg/dL | Rifampicin (Rifampin) | 4.80 mg/dL |
| Digoxin | 3.90 μg/dL | Salicylic acid | 2.86 mg/dL |
| Diphenhydramine HCl | 77.4 μg/dL | Salmeterol | 1.65 μg/dL |
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| Compound | Concentration | Compound | Concentration |
| --- | --- | --- | --- |
| Dipyrone (as 4-methylaminoantipyrine Hydrochloride) | 3.30 mg/dL | Sotalol hydrochloride | 510 μg/dL |
| Dypyridamole | 1.00 mg/dL | Spironolactone | 55.5 μg/dL |
| Doxycycline hyclate | 1.80 mg/dL | Streptokinase | 150,000 U/dL |
| Enalaprilat dihydrate | 81.9 μg/dL | Theophylline | 6.00 mg/dL |
| Ethanol | 600 mg/dL | Tolbutamide | 54.9 mg/dL |
| Fibrinogen | 1000 mg/dL | Total Protein | 15.0 g/dL |
| Furosemide | 1.59 mg/dL | tPA (Alteplase) | 1.20 mg/dL |
| Gentamicin Sulfate | 3.51 mg/dL | Triglyceride | 1500 mg/dL |
| Glycerylnitrate (Nitroglycerin) | 1.20 μg/dL | Valproic Acid | 31.8 mg/dL |
| HAMA (Human Anti-Mouse Antibody) | 800 μg/L | Vancomycin Hydrochloride | 12.3 mg/dL |
| Hemoglobin | 1000 mg/dL | Verapamil Hydrochloride | 160 μg/dL |
| Heparin (Sodium), UFH | 330 U/dL | Warfarin | 8.00 mg/dL |
The interference study demonstrated that cefoxitin sodium and sodium azide interferes with the VITROS® NT-proBNP II assay. Cefoxitin sodium interfered with the candidate device at concentrations above 311 mg/dL, which is above the expected therapeutic concentration of this compound and is therefore not expected to cause significantly interfere with this device. Sodium azide interfered with the candidate device at concentrations above 85.9 mg/dL. Sodium azide is a preservative used in some hospital and laboratory equipment that is not expected to be found in patient samples; therefore, sodium azide is not expected to significantly interfere with this device. The results are shown below.
| Interferent | Interferent Concentration mg/dL | In the presence of the average NT-proBNP concentration pg/mL | Mean %Bias |
| --- | --- | --- | --- |
| Cefoxitin sodium | 697 | 84.3 | -24.1 |
| | | 922 | -19.1 |
| | 311 | 105 | -10.0 |
| | 306 | 806 | -10.0 |
| Sodium Azide | 100 | 91.4 | -12.1 |
| | 85.9 | 93.6 | -10.0 |
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The sponsor has the following limitation statements included in the labeling:
- Heterophilic antibodies in serum or plasma samples may cause interference in immunoassays. These antibodies may be present in blood samples from individuals regularly exposed to animals or who have been treated with animal serum products. Results that are inconsistent with clinical observations indicate the need for additional testing.
- The VITROS® NT-proBNP II test has no high dose hook effect up to a concentration of 300,000 pg/mL (35,400 pmol/L).
Cross-reactivity in the absence and presence of NT-proBNP: The cross-reactivity of the VITROS® NT-proBNP II Reagent Pack was evaluated by adding the substances listed in the tables below to a human serum sample that did not contain NT-proBNP and to a sample containing NT-proBNP at a concentration of 125 pg/mL. Percent cross-reactivity was expressed as the mean result obtained for the cross-reactant sample minus the mean result obtained for the control sample divided by the cross-reactant concentration multiplied by 100. The results showed that the cross-reactivity of proBNP (glycosylated) and proBNP (nonglycosylated) was greater than 1.0% when tested in samples in which NT-proBNP was and was not present. Cross-reactivity of NT-proBNP assays to proBNP has been documented previously. The results of the cross-reactivity testing are presented below.
Cross-reactivity in absence of NT-proBNP
| Cross-reactant | Concentration | Mean result of control sample pg/mL | Mean result of cross-reactant sample pg/mL | Percent cross-reactivity |
| --- | --- | --- | --- | --- |
| ANP28 | 3.10 μg/mL | * | * | * |
| proBNP (glycosylated) | 3000 pg/mL | -0.14 | 57.6 | 1.9 |
| proBNP (nonglycosylated) | 3000 pg/mL | -0.48 | 863 | 28.8 |
| NT-proANP1–30 (preproANP25–55) | 3.50 μg/mL | * | * | * |
| NT-proANP31–67 (preproANP56–92) | 1.00 ng/mL | * | * | * |
| NT-proANP79–98 (preproANP104–123) | 1.00 ng/mL | * | * | * |
| BNP32 (Natrecor®) | 3.50 μg/mL | * | * | * |
| CNP22 | 2.20 μg/mL | * | * | * |
| Adrenomedullin | 1.00 ng/mL | * | * | * |
| Aldosterone | 0.600 ng/mL | * | * | * |
| Angiotensin I | 0.600 ng/mL | * | * | * |
| Angiotensin II | 0.600 ng/mL | * | * | * |
| Angiotensin III | 1.00 ng/mL | * | * | * |
| Endothelin | 20.0 pg/mL | * | * | * |
| Urodilatin | 3.50 μg/mL | * | * | * |
| Arg-Vasopressin | 1.00 μg/mL | * | * | * |
| Renin | 50.0 ng/mL | * | * | * |
*Not detectable. Concentration was below the measuring range of the test, 20.0–30,000 pg/mL.
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Cross-reactivity in the presence of 125 pg/mL NT-proBNP
| Cross-reactant | Concentration | Mean NT-proBNP result of control sample pg/mL | Mean NT-proBNP result of cross-reactant sample pg/mL | Percent cross-reactivity |
| --- | --- | --- | --- | --- |
| ANP28 | 3.10 μg/mL | 112 | 113 | <1.0 |
| proBNP (glycosylated) | 3000 pg/mL | 105 | 183 | 2.6 |
| proBNP (nonglycosylated) | 3000 pg/mL | 118 | 1290 | 39.1 |
| NT-proANP1–30 (preproANP25–55) | 3.50 μg/mL | 113 | 775 | <1.0 |
| NT-proANP31–67 (preproANP56–92) | 1.00 ng/mL | 112 | 113 | <1.0 |
| NT-proANP79–98 (preproANP104–123) | 1.00 ng/mL | 112 | 114 | <1.0 |
| BNP32 (Natrecor®) | 3.50 μg/mL | 112 | 115 | <1.0 |
| CNP22 | 2.20 μg/mL | 112 | 114 | <1.0 |
| Adrenomedullin | 1.00 ng/mL | 112 | 114 | <1.0 |
| Aldosterone | 0.600 ng/mL | 112 | 117 | <1.0 |
| Angiotensin I | 0.600 ng/mL | 112 | 112 | <1.0 |
| Angiotensin II | 0.600 ng/mL | 112 | 111 | <1.0 |
| Angiotensin III | 1.00 ng/mL | 112 | 112 | <1.0 |
| Endothelin | 20.0 pg/mL | 113 | 113 | <1.0 |
| Urodilatin | 3.50 μg/mL | 112 | 114 | <1.0 |
| Arg-Vasopressin | 1.00 μg/mL | 112 | 117 | <1.0 |
| Renin | 50.0 ng/mL | 112 | 112 | <1.0 |
**High dose hook effect:**
The VITROS® NT-proBNP II Reagent Pack was evaluated for high dose hook effect using nine levels of recombinant NT-BNP II. The results support that the VITROS® NT-proBNP II Reagent Pack does not show a high dose hook effect up to 300,000 pg/mL of NT-proBNP.
4. **Assay Reportable Range:**
Based on the results from linearity and detection limit studies, the sponsor claims an assay reportable range of 20.0 to 30,000 pg/mL for the VITROS® NT-proBNP II Reagent Pack on the VITROS 3600 Immunodiagnostic System.
**Dilution of high samples:**
Serum or plasma (K₂ EDTA or lithium heparin) samples with concentrations up to 41,570 pg/mL can be measured after a 10-fold dilution. The percent recovery of diluted samples (up to 41,570 pg/mL) ranged from 91.5% to 109.6%.
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5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
Traceability:
The product calibrators for the VITROS® NT-proBNP II Reagent Pack are traceable to reference calibrators consisting of recombinant NT-proBNP in citrate buffer that were value assigned using a commercially available assay. The VITROS Immunodiagnostic Products NT-proBNP II Calibrators are value assigned using the reference calibrators on a lot-to-lot basis.
Sample Stability:
The sponsor provided data to support sample stability at different temperatures:
- K₂EDTA plasma, lithium heparin plasma, and serum samples are stable for up to 96 hours stored at 68-77°F (20-25°C).
- K₂EDTA plasma, lithium heparin plasma, and serum samples are stable for up to 26 weeks stored at ≤-4°F (≤-20°C).
The sponsor also provided data to support that samples stored frozen at ≤-4°F (≤-20°C) may be subjected to up to three (3) freeze-thaw cycles.
6. Detection Limit:
The CLSI EP17-A2 guideline was referenced to design the limit of blank (LoB), limit of detection (LoD) and limit of quantitation (LoQ) studies.
Limit of Blank (LoB):
LoB was determined by running 100 replicates for each of four (4) blank samples consisting of human serum/buffer matrix fluid over five days, measuring two runs per day, ten replicates per run, across three lots using the VITROS® NT-proBNP II Reagent Pack on one VITROS 3600 Immunodiagnostic System. A parametric method was used to evaluate the data, and the highest value obtained from three lots was claimed.
- The LoB for the VITROS® NT-proBNP II assay is estimated to be 0.034 pg/mL.
Limit of Detection (LoD):
LoD was assessed using seven (7) samples with low levels of NT-proBNP. These samples were prepared using bulk human serum samples to give approximate target levels in the range of one to six times the estimated LoB. The LoD was calculated by assaying ten replicates of each sample, on two runs per day for five days giving a total of 100 determinations of each sample lot. These determinations were run using three VITROS® NT-proBNP II Reagent Pack master lots on one VITROS 3600 Immunodiagnostic System. The limit of detection (LoD) for the VITROS® NT-proBNP II assay was determined by parametric analysis to be 0.46 pg/mL.
- The LoD claimed for the VITROS® NT-proBNP II assay is 0.49 pg/mL.
Limit of Quantitation (LoQ):
The LoQ was calculated as the lowest concentration of NT-proBNP that can be measured with a coefficient of variation (CV) of at least 20%. The LoQ was calculated using the seven
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sample results from the LoD testing. The % CV for each sample was plotted vs. the mean concentration of NT-proBNP measured in each sample and a power function model was fit to the data. The limit of quantitation (LoQ) for the VITROS® NT-proBNP II assay was determined to be 0.18 pg/mL (highest value obtained from three reagent lots tested). Since the calculated LoQ is lower than the claimed LoD, the LoQ is set to be equal to LoD at 0.46 pg/mL.
- The sponsor claims the LoQ as 20.0 pg/mL.
7. Assay Cut-Off:
See expected values below.
B Comparison Studies:
1. Method Comparison with Predicate Device:
Not Applicable: see clinical studies in Section C.
2. Matrix Comparison:
The sponsor conducted a matrix comparison study to support their matrix claims. 160 unaltered matched serum, K₂EDTA plasma and lithium heparin plasma samples containing NT-proBNP concentrations from 21.7 pg/mL to 26550 pg/mL were tested. Each serum sample was tested in duplicate while the lithium heparin plasma and K2-EDTA plasma samples were assayed in singleton using one VITROS 3600 Immunodiagnostic System. The results were analyzed using Passing-Bablok regression and Pearson correlation coefficient (r). The study results support claims for testing serum, K₂ EDTA plasma, and lithium heparin plasma samples with the VITROS® NT-proBNP II Reagent Pack on the VITROS 3600 Immunodiagnostic System.
| Items | Serum vs. K₂EDTA plasma | Serum vs. Li-heparin plasma |
| --- | --- | --- |
| NT-proBNP II range (pg/mL) | 21.7 pg/mL to 26550 pg/mL | |
| Number of matched samples | 160 | 160 |
| Slope | 0.98 | 1.00 |
| y-intercept | 2.24 | 2.75 |
| Regression Coefficient R | 0.999 | 1.00 |
C Clinical Studies:
1. Clinical Sensitivity:
See section 3 below.
2. Clinical Specificity:
See section 3 below.
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3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):
Aid in Diagnosis of Heart Failure (HF):
Population 1 Emergency Department (ED):
A multi-center prospective study including 20 collection sites across the United States was conducted to establish the performance characteristics of the VITROS® NT-proBNP II Reagent Pack. Subjects 22 years and older presenting to the ED with dyspnea (acute or worsening) and clinical suspicion of heart failure (HF) were enrolled in the study. Subjects with terminal kidney failure on chronic dialysis and subjects with dyspnea clearly not secondary to HF were excluded from the study. The final clinical diagnosis was adjudicated by independent cardiologists or ED physicians experienced in diagnosing HF. The VITROS® NT-proBNP II Reagent Pack results were determined from samples collected from 2200 ED subjects consisting of 1016 (46.18%) female subjects and 1184 (53.82%) male subjects ranging in age from 22 to 106 years. Individuals in the population were African American (36.55%) and Caucasian (59.59%), with the remaining 3.86% represented by other races. Samples were frozen prior to analysis. Data supporting the stability of the samples for the storage time and condition were provided by the sponsor.
The descriptive statistics for the VITROS® NT-proBNP II Reagent Pack results (pg/mL) were determined within and across sex by age group and are summarized in the following tables:
Female subjects:
| Study Population | Heart Failure | | | | Non-Heart Failure | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age (years) | 22 - < 50 | 50 - < 75 | ≥ 75 | All | 22 - < 50 | 50 - <75 | ≥ 75 | All |
| # of subjects | 43 | 194 | 217 | 454 | 71 | 306 | 185 | 562 |
| Mean (pg/mL) | 10300 | 6830 | 7790 | 7620 | 196 | 648 | 948 | 690 |
| SD (pg/mL) | 32200 | 10000 | 10600 | 13900 | 356 | 1800 | 1280 | 1540 |
| Median (pg/mL) | 1920 | 3620 | 4710 | 3850 | 68.2 | 157 | 444 | 226 |
| Min (pg/mL) | 20.0 | 102 | 296 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 |
| Max (pg/mL) | 178000 | 86300 | 94600 | 178000 | 2010 | 23800 | 7870 | 23800 |
Male subjects:
| Study Population | Heart Failure | | | | Non-Heart Failure | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age (years) | 22 - < 50 | 50 - < 75 | ≥ 75 | All | 22 - < 50 | 50 - <75 | ≥ 75 | All |
| # of subjects | 71 | 344 | 226 | 641 | 70 | 324 | 149 | 543 |
| Mean (pg/mL) | 4720 | 6330 | 7830 | 6680 | 326 | 737 | 1330 | 846 |
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| Study Population | Heart Failure | | | | Non-Heart Failure | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age (years) | 22 - < 50 | 50 - < 75 | ≥ 75 | All | 22 - < 50 | 50 - <75 | ≥ 75 | All |
| SD (pg/mL) | 6780 | 9170 | 9730 | 9180 | 718 | 1640 | 2080 | 1720 |
| Median (pg/mL) | 2260 | 3480 | 5020 | 3690 | 43.6 | 203 | 519 | 275 |
| Min (pg/mL) | 195 | 53.7 | 295 | 53.7 | 20.0 | 20.0 | 20.0 | 20.0 |
| Max (pg/mL) | 39200 | 70400 | 86000 | 86000 | 4710 | 17100 | 13600 | 17100 |
All subjects:
| Study Population | Heart Failure | | | | Non-Heart Failure | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age (years) | 22 - < 50 | 50 - < 75 | ≥ 75 | All | 22 - < 50 | 50 - <75 | ≥ 75 | All |
| # of subjects | 114 | 538 | 443 | 1095 | 141 | 630 | 334 | 1105 |
| Mean (pg/mL) | 6840 | 6510 | 7810 | 7070 | 261 | 694 | 1120 | 767 |
| SD (pg/mL) | 20500 | 9490 | 10100 | 11400 | 568 | 1720 | 1690 | 1630 |
| Median (pg/mL) | 2150 | 3550 | 4850 | 3780 | 58.4 | 177 | 473 | 247 |
| Min (pg/mL) | 20.0 | 53.7 | 295 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 |
| Max (pg/mL) | 178000 | 86300 | 94600 | 178000 | 4710 | 23800 | 13600 | 23800 |
VITROS® NT-proBNP II Test Results versus Adjudicated Diagnosis within and across Age Group
| Age (Years) | VITROS® NT-proBNP II Test Result | Adjudicated Diagnosis | | Total | |
| --- | --- | --- | --- | --- | --- |
| | | | HF | | Non-HF |
| 22-<50 | VITROS® NT-proBNP II Test Result Interpretation | Positive | 105 | 19 | 124 |
| | | Gray Zone | 5 | 13 | 18 |
| | | Negative | 4 | 109 | 113 |
| | | Total | 114 | 141 | 255 |
| 50-<75 | VITROS® NT-proBNP II Test Result Interpretation | Positive | 472 | 115 | 587 |
| | | Gray Zone | 59 | 144 | 203 |
| | | Negative | 7 | 371 | 378 |
| | | Total | 538 | 630 | 1168 |
| ≥75 | VITROS® NT-proBNP II Test | Positive | 372 | 62 | 434 |
| | | Gray Zone | 69 | 153 | 222 |
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| Age (Years) | VITROS® NT-proBNP II Test Result | Adjudicated Diagnosis | | Total | |
| --- | --- | --- | --- | --- | --- |
| | | | HF | | Non-HF |
| | Result Interpretation | Negative | 2 | 119 | 121 |
| | | Total | 443 | 334 | 777 |
| All Subjects | VITROS® NT-proBNP II Test Result Interpretation | Positive | 949 | 196 | 1145 |
| | | Gray Zone | 133 | 310 | 443 |
| | | Negative | 13 | 599 | 612 |
| | | Total | 1095 | 1105 | 2200 |
The pretest probability of HF (prevalence of HF in the study), posttest probabilities, likelihood ratios and the two-tailed 95% CIs of the VITROS® NT-proBNP II test result versus adjudicated diagnosis were determined across and within sex using the age-dependent rule-in (450 pg/mL for subjects 22-<50 years old; 900 pg/mL for subjects 50-<75 years old; 1800 pg/mL for subjects ≥75 years old) and age-independent rule-out (300 pg/mL) cutoffs and are summarized in the following tables:
All Subjects
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-< 50 (N = 255) | 44.7% (114/255) | Positive | 84.7 (105/124) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 27.8 (5/18) | 12.5–50.9 | 72.2 (13/18) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 96.5 (109/113) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-< 75 (N=1168) | 46.1% (538/1168) | Positive | 80.4 (472/587) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 29.1 (59/203) | 23.3–35.7 | 70.9 (144/203) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 98.1 (371/378) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=777) | 57% (443/777) | Positive | 85.7 (372/434) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
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| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| | | Gray zone | 31.1 (69/222) | 25.4–37.4 | 68.9 (153/222) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 98.3 (119/121) | 94.2–99.5 | 0.01 | 0.00–0.05 |
| All Subjects (N=2200) | 49.8% (1095/2200) | Positive | 82.9 (949/1145) | 80.6–85.0 | – | – | 4.89 | 4.29–5.56 |
| | | Gray zone | 30.0 (133/443) | 25.9–34.4 | 70.0 (310/443) | 65.6–74.1 | 0.43 | 0.36–0.52 |
| | | Negative | – | – | 97.9 (599/612) | 96.4–98.8 | 0.02 | 0.01–0.04 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
The pretest probability of HF (prevalence of HF in the study), posttest probabilities, likelihood ratios and the two-tailed 95% CIs of the VITROS® NT-proBNP II test result versus adjudicated diagnosis were determined for the relevant clinical subgroups using the age-dependent rule-in (450 pg/mL for subjects 22-<50 years old; 900 pg/mL for subjects 50-<75 years old; 1800 pg/mL for subjects ≥75 years old) and age-independent rule-out (300 pg/mL) cutoffs and are summarized in the following tables:
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Female Subjects
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=114) | 37.70% (43/114) | Positive | 88.6 (39/44) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 11.1 (1/9) | 12.5–50.9 | 88.9 (8/9) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 95.1 (58/61) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=500) | 38.80% (194/500) | Positive | 77 (167/217) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 26.4 (23/87) | 23.3–35.7 | 73.6 (64/87) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 98 (192/196) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=402) | 54% (217/402) | Positive | 85.9 (176/205) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 30.5 (40/131) | 25.4–37.4 | 69.5 (91/131) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 98.5 (65/66) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
Male Subjects
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=141) | 50.40% (71/141) | Positive | 82.5 (66/80) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 44.4 (4/9) | 12.5–50.9 | 55.6 (5/9) | 49.1–87.5 | 0.48 | 0.17–1.29 |
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| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| | | Negative | - | - | 98.1 (51/52) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50–<75 (N=668) | 51.50% (344/668) | Positive | 82.4 (305/370) | 77.0–83.4 | - | - | 4.81 | 4.06–5.69 |
| | | Gray zone | 31 (36/116) | 23.3–35.7 | 69 (80/116) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | - | - | 98.4 (179/182) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=375) | 60.30% (226/375) | Positive | 85.6 (196/229) | 82.1–88.7 | - | - | 4.52 | 3.60–5.68 |
| | | Gray zone | 31.9 (29/91) | 25.4–37.4 | 68.1 (62/91) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | - | - | 98.2 (54/55) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
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Subjects with a History of HF
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=118) | 73.7% (87/118) | Positive | 92.9 (79/85) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 36.4 (4/11) | 12.5–50.9 | 63.6 (7/11) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 81.8 (18/22) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=642) | 63.1% (405/642) | Positive | 87.2 (355/407) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 38.1 (43/113) | 23.3–35.7 | 61.9 (70/113) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 94.3 (115/122) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=460) | 71.1% (327/460) | Positive | 90.5 (275/304) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 41.1 (51/124) | 25.4–37.4 | 58.9 (73/124) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 96.9 (31/32) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
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Subjects with no History of HF
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=137) | 19.7% (27/137) | Positive | 66.7 (26/39) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 14.3 (1/7) | 12.5–50.9 | 85.7 (6/7) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 100 (91/91) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=521) | 25.3% (132/521) | Positive | 65.2 (116/178) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 17.8 (16/90) | 23.3–35.7 | 82.2 (74/90) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 100 (253/253) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=312) | 36.9% (115/312) | Positive | 75 (96/128) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 18.8 (18/96) | 25.4–37.4 | 81.3 (78/96) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 98.9 (87/88) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
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Subjects with eGFR <60***mL/min/1.73 m²
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=69) | 62.30% (43/69) | Positive | 87.2 (41/47) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 16.7 (1/6) | 12.5–50.9 | 83.3 (5/6) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 93.8 (15/16) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=476) | 56.50% (269/476) | Positive | 79.6 (250/314) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 24.7 (18/73) | 23.3–35.7 | 75.3 (55/73) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 98.9 (88/89) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=467) | 68.10% (318/467) | Positive | 88.6 (273/308) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 37.6 (44/117) | 25.4–37.4 | 62.4 (73/117) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 97.6 (41/42) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
*** Subjects with renal disease on dialysis were excluded from the study
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Subjects with eGFR ≥60***mL/min/1.73 m²
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=181) | 38.70% (70/181) | Positive | 82.9 (63/76) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 36.4 (4/11) | 12.5–50.9 | 63.6 (7/11) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 96.8 (91/94) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=679) | 38.70% (263/679) | Positive | 81 (217/268) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 31.3 (40/128) | 23.3–35.7 | 68.8 (88/128) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 97.9 (277/283) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=306) | 40.20% (123/306) | Positive | 78.2 (97/124) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 24 (25/104) | 25.4–37.4 | 76 (79/104) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 98.7 (77/78) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
*** Subjects with renal disease on dialysis were excluded from the study
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Subjects with BMI $\geq 30\ \mathrm{kg/m^2}$
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22–<50 (N=188) | 48.9% (92/188) | Positive | 90.2 (83/92) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 27.8 (5/18) | 12.5–50.9 | 72.2 (13/18) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 94.9 (74/78) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50–<75 (N=693) | 46.3% (321/693) | Positive | 80.9 (266/329) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 36.1 (48/133) | 23.3–35.7 | 63.9 (85/133) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 97 (224/231) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=279) | 55.9% (156/279) | Positive | 84.6 (121/143) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 37.8 (34/90) | 25.4–37.4 | 62.2 (56/90) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 97.8 (45/46) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
K201312 - Page 23 of 32
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Subjects with BMI <30 kg/m²
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=62) | 35.5% (22/62) | Positive | 68.8 (22/32) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | ∞ (0/0) | 12.5–50.9 | ∞ (0/0) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 100 (30/30) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=465) | 46.5% (216/465) | Positive | 79.8 (206/258) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 14.7 (10/68) | 23.3–35.7 | 85.3 (58/68) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 100 (139/139) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=498) | 57.6% (287/498) | Positive | 86.3 (251/291) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 26.5 (35/132) | 25.4–37.4 | 73.5 (97/132) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 98.7 (74/75) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
K201312 - Page 24 of 32
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Subjects with Comorbidities
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=178) | 55.1% (98/178) | Positive | 86.8 (92/106) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 23.1 (3/13) | 12.5–50.9 | 76.9 (10/13) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 94.9 (56/59) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=1066) | 47.3% (504/1066) | Positive | 80.2 (438/546) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 32.1 (59/184) | 23.3–35.7 | 67.9 (125/184) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 97.9 (329/336) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=734) | 57.2% (420/734) | Positive | 86.1 (352/409) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 31.7 (66/208) | 25.4–37.4 | 68.3 (142/208) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 98.3 (115/117) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
*** Subjects with at least one of the following: diabetes, renal insufficiency (eGFR values <60), hypertension (HTN) and/or chronic obstructive pulmonary disease (COPD)
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Subjects without Comorbidities
| Age Group (Years) | Pretest Probability of HF (Prevalence of HF in Study) (n/N) | VITROS® NT-proBNP II Test Result Interpretation | Posttest Probability of HF (n/N) | | Posttest Probability of non-HF (n/N) | | Likelihood Ratio Positive (HF) | 95% CI** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | Estimate (%) | 95% CI* (%) | Estimate (%) | 95% CI* (%) | | |
| 22-<50 (N=77) | 20.8% (16/77) | Positive | 72.2 (13/18) | 77.3–90.0 | – | – | 6.84 | 4.48–10.42 |
| | | Gray zone | 40 (2/5) | 12.5–50.9 | 60 (3/5) | 49.1–87.5 | 0.48 | 0.17–1.29 |
| | | Negative | – | – | 98.1 (53/54) | 91.3–98.6 | 0.05 | 0.02–0.12 |
| 50-<75 (N=102) | 33.3% (34/102) | Positive | 82.9 (34/41) | 77.0–83.4 | – | – | 4.81 | 4.06–5.69 |
| | | Gray zone | 0 (0/19) | 23.3–35.7 | 100 (19/19) | 64.3–76.7 | 0.48 | 0.36–0.63 |
| | | Negative | – | – | 100 (42/42) | 96.2–99.1 | 0.02 | 0.01–0.05 |
| ≥75 (N=43) | 53.5% (23/43) | Positive | 80 (20/25) | 82.1–88.7 | – | – | 4.52 | 3.60–5.68 |
| | | Gray zone | 21.4 (3/14) | 25.4–37.4 | 78.6 (11/14) | 62.6–74.6 | 0.34 | 0.27–0.43 |
| | | Negative | – | – | 100 (4/4) | 94.2–99.5 | 0.01 | 0.00–0.05 |
* 95% Wilson Score Confidence Interval
** Log Method Confidence Interval
*** Subjects with at least one of the following: diabetes, renal insufficiency (eGFR values <60), hypertension (HTN) and/or chronic obstructive pulmonary disease (COPD)
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# Population 2 – Outpatient Setting:
The VITROS® NT-proBNP II Reagent Pack results were determined from 777 subjects, 391 females and 386 males ranging in age from 23 to 94 years presenting to cardiology clinics and other outpatient facilities with a clinical suspicion of HF (not previously diagnosed) and at least one HF sign, symptom or risk factor at 10 collection sites across the United States. Subjects with terminal kidney failure on chronic dialysis and subjects with dyspnea clearly not secondary to HF were excluded from the study. The final clinical diagnosis was adjudicated by independent cardiologists or ED physicians experienced in diagnosing HF. Individuals in the population were African American (31.66%) and Caucasian (64.74%), with the remaining 3.60% represented by other races. The clinical performance and the two-tailed 95% CIs of the VITROS® NT-proBNP II Reagent Pack results versus adjudicated diagnosis for subjects presenting to cardiology clinics and other outpatient facilities was determined using the rule-out cutoff (125 pg/mL) and are summarized in the following tables:
All subjects:
| Group | Cutoff pg/mL | Sensitivity (%) (n/N) | 95% CI* (%) | Specificity (%) (n/N) | 95% CI* (%) | NPV (%) (n/N) | 95% CI* (%) | PPV (%) (n/N) | 95% CI* (%) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| All Subjects (N=777) | 125 | 91.7 (44/48) | 80.0 - 97.7 | 67.2 (490/729) | 63.7 - 70.6 | 99.2 (490/494) | 97.9 - 99.8 | 15.6 (44/283) | 11.5 - 20.3 |
*95% Exact Confidence Interval
Performance Characteristics of the VITROS® NT-proBNP II Assay Within and Across Sex
| Sex | N | Sensitivity (%) (n/N) | 95% CI (%)* | Specificity (%) (n/N) | 95% CI (%)* | NPV (%) (n/N) | 95% CI (%)* | PPV (%) (n/N) | 95% CI (%)* |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Female | 391 | 90.5 (19/21) | 69.6 - 98.8 | 68.1 (252/370) | 63.1 - 72.8 | 99.2 (252/254) | 97.2 - 99.9 | 13.9 (19/137) | 8.6 - 20.8 |
| Male | 386 | 92.6 (25/27) | 75.7 - 99.1 | 66.3 (238/359) | 61.2 - 71.2 | 99.2 (238/240) | 97.0 - 99.9 | 17.1 (25/146) | 11.4 - 24.2 |
*95% Exact Confidence Interval
Subjects stratified by age:
| Clinical Subgroups | Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | NPV (%) (95% CI) | PPV (%) (95% CI) |
| --- | --- | --- | --- | --- |
| ≥75 Years old (N=139) | 93.8 (69.8 - 99.8) | 36.6 (28.1 - 45.8) | 97.8 (88.5 - 99.9) | 16.1 (9.3 - 25.2) |
| <75 Years old (N=638) | 90.6 (75.0 - 98.0) | 73.4 (69.7 - 76.9) | 99.3 (98.1 - 99.9) | 5.0 (3.5 - 7.0) |
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Subjects stratified by eGFR
| Clinical Subgroups | Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | NPV (%) (95% CI) | PPV (%) (95% CI) |
| --- | --- | --- | --- | --- |
| eGFR <60*
mL/min/1.73 m2
(N=81) | 84.6
(54.6 - 98.1) | 45.6
(33.5 - 58.1) | 93.9
(79.8 - 99.3) | 22.9
(12.0 - 37.3) |
| eGFR ≥ 60
mL/min/1.73 m2
(N=245) | 100.0
(75.3 - 100.0) | 68.5
(62.1 - 74.5) | 100.0
(97.7 - 100.0) | 15.1
(8.3 - 24.5) |
*Subjects with renal disease on dialysis were excluded from the study
Subjects stratified by BMI
| Clinical Subgroups | Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | NPV (%) (95% CI) | PPV (%) (95% CI) |
| --- | --- | --- | --- | --- |
| BMI ≥ 30.0
kg/m2 (N=430) | 82.6
(61.2 - 95.1) | 76.2
(71.7 - 80.2) | 98.7
(96.8 - 99.7) | 16.4
(10.2 - 24.4) |
| BMI < 30.0
kg/m2 (N=346) | 100.0
(85.8 - 100.0) | 55.9
(50.3 - 61.4) | 100.0
(98.0 - 100.0) | 14.5
(9.5 - 20.7) |
Subjects stratified by the presence or absence of comorbidities
| Clinical Subgroups | Sensitivity (%) (95% CI) | Specificity (%) (95% CI) | NPV (%) (95% CI) | PPV (%) (95% CI) |
| --- | --- | --- | --- | --- |
| With comorbidities*
(N=660) | 100.0
(90.8 - 100.0) | 6.4
(4.6 - 8.7) | 100.0
(91.2 - 100.0) | 6.1
(4.4 - 8.3) |
| Without comorbidities**
(N=117) | 90.0
(55.5 - 99.8) | 4.7
(1.5 - 10.6) | 83.3
(35.9 - 99.6) | 8.1
(3.8 - 14.8) |
*Subjects with at least one of the following: diabetes, renal insufficiency (eGFR values <60), hypertension (HTN) and/or chronic obstructive pulmonary disease (COPD)
**Subjects without any of the following: diabetes, renal insufficiency (eGFR values <60), hypertension (HTN) and/or chronic obstructive pulmonary disease (COPD)
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In the labeling, the sponsor states “the results of this assay should be used in conjunction with clinical presentation, other diagnostic tests, and in accordance with the appropriate clinical guidelines.”
Correlation of the VITROS® NT-proBNP II Reagent Pack results with New York Heart Association (NYHA) functional classification in patients diagnosed with HF:
The VITROS® NT-proBNP II Reagent Pack results were determined from samples from 1143 subjects with heart failure ranging in age from 22 to 106 years. The population consisted of 475/1143 (41.56%) females and 668/1143 (58.44%) males. The descriptive statistics for the VITROS® NT-proBNP II Reagent results (pg/mL) were determined across gender and are summarized in the following table:
All Subjects
| Statistics | NYHA Functional Classification | | | |
| --- | --- | --- | --- | --- |
| | NYHA Class I* | NYHA Class II | NYHA Class III | NYHA Class IV |
| N | 8 | 190 | 567 | 378 |
| Mean | 4190 | 5010 | 6680 | 8170 |
| SD | 5910 | 8410 | 9770 | 14100 |
| 5th Percentile | 156 | 291 | 490 | 701 |
| Median | 1480 | 2220 | 3660 | 4520 |
| IQR | 6360 | 4330 | 5920 | 7810 |
| 95th Percentile | 16000 | 17900 | 23100 | 23400 |
*There were no NYHA Class I female subjects in the study
Jonckheere-Terpstra test of trend p <0.0001
Female Subjects
| Statistics | NYHA Functional Classification | | | |
| --- | --- | --- | --- | --- |
| | NYHA Class I* | NYHA Class II | NYHA Class III | NYHA Class IV |
| N | N/A | 85 | 240 | 150 |
| Mean | N/A | 4560 | 6650 | 9970 |
| SD | N/A | 6150 | 9860 | 20100 |
| 5th Percentile | N/A | 272 | 481 | 559 |
| Median | N/A | 2190 | 3510 | 4790 |
| IQR | N/A | 4250 | 6310 | 8580 |
| 95th Percentile | N/A | 16200 | 24400 | 25800 |
*There were no NYHA Class I female subjects in the study
Jonckheere-Terpstra test of trend p <0.0001
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Male Subjects
| Statistics | NYHA Functional Classification | | | |
| --- | --- | --- | --- | --- |
| | NYHA Class I | NYHA Class II | NYHA Class III | NYHA Class IV |
| N | 8 | 105 | 327 | 228 |
| Mean | 4190 | 5380 | 6700 | 6980 |
| SD | 5910 | 9890 | 9710 | 7760 |
| 5th Percentile | 156 | 404 | 516 | 733 |
| Median | 1480 | 2220 | 3730 | 4280 |
| IQR | 6360 | 4380 | 5700 | 7140 |
| 95th Percentile | 16000 | 17900 | 20200 | 21600 |
Jonckheere-Terpstra test of trend p <0.0001
In the labeling, the sponsor states the following:
The Jonckheere-Terpstra test was used to determine that there is a statistically significant relationship between the median VITROS® NT-proBNP II test results and HF severity for:
- All Subjects NYHA Class II-IV.
- Female Subjects NYHA Class II-IV.
- Male Subjects NYHA Class I-IV.
These results show that there is a relationship between the median VITROS® NT-proBNP II test results and HF severity as determined by NYHA Class.
## D Clinical Cut-Off:
## Emergency Department Settings
For patients in the Emergency Department (ED) settings, the VITROS® NT-proBNP II assay results should be interpreted as indicated in the table below.
| VITROS® NT-proBNP II Test Results (pg/mL) | Age Group (Years) | Interpretation of Results |
| --- | --- | --- |
| <300 | All | Negative: Heart Failure Unlikely |
| | | |
| ≥300 to <450 | 22-<50 | Gray Zone: Indeterminate – Consider other causes of NT-proBNP elevation* |
| ≥300 to <900 | 50-<75 | |
| ≥300 to <1800 | ≥75 | |
| | | |
| ≥450 | 22-<50 | Positive: Heart Failure Likely |
| ≥900 | 50-<75 | |
| ≥1800 | ≥75 | |
*Natriuretic peptides values in the gray zone could also be caused by several conditions other than heart failure. Clinical conditions such as valvular abnormalities, acute coronary syndrome, heart muscle disease, pulmonary embolism, pulmonary hypertension, sepsis, stroke, cardiotoxic
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drugs, and renal dysfunction will elevate NT-proBNP levels; obesity, flash pulmonary edema, cardiac tamponade, and pericardial constriction are conditions associated with reduced NT-proBNP.
The sponsor included the following statements in their instructions for use concerning the performance of their device in ED settings in certain clinical subgroups:
- The posttest probability of heart failure in female subjects between the ages of 50 and <75 with a positive result was low (77.0%). In the study, 23% of female subjects between the ages of 50 and <75 with a positive test result did not have an adjudicated diagnosis of heart failure (HF, false positives).
- The posttest probability of heart failure in subjects with no history of HF with a positive result was low (69.0%). In the study, 31.0% of subjects with no history of HF who had a positive test result did not have an adjudicated diagnosis of HF (false positives).
- The posttest probability of not having heart failure in subjects with no history of HF between the ages of 22 and <50 with a negative result was low (81.8%). In the study, 18.2% of subjects between the ages of 22 and <50 with no history of HF with a negative test result had an adjudicated diagnosis of HF (false negatives).
- The posttest probability of heart failure in subjects with eGFR ≥60 mL/min/1.73 m2 ≥75 years of age with a positive result was low (78.2%). In the study, 21.8% of subjects with eGFR ≥60 mL/min/1.73 m2 ≥75 years of age with a positive test result did not have an adjudicated diagnosis of HF (false positives).
- The posttest probability of heart failure in subjects with BMI <30 kg/m2 between the ages of 22 and <50 with a positive test result was low (68.8%). In the study, 31.2% of subjects with BMI <30 kg/m2 between the ages of 22 and <50 with a positive test result did not have an adjudicated diagnosis of HF (false positives).
- The posttest probability of heart failure in subjects without Comorbidities (diabetes, renal insufficiency (eGFR values <60), hypertension (HTN) and/or chronic obstructive pulmonary disease (COPD)) between the ages of 22 and <50 was low (79.8%). In the study, 20.2% of subjects without comorbidities between the ages of 22 and <50 with a positive test result did not have an adjudicated diagnosis of HF (false positives).
## Outpatient Settings
For patients in the outpatient settings, the VITROS® NT-proBNP II test results should be interpreted as indicated in the table below.
| VITROS® NT-proBNP II Test Results (pg/mL) | Age Group | Interpretation of Results |
| --- | --- | --- |
| <125 | All | Negative: Heart Failure Unlikely. |
| ≥125 | All | Consider Heart Failure as well as other causes* of NT-proBNP elevation. |
* Natriuretic peptides values elevations could also be caused by several conditions other than heart failure such as valvular abnormalities, acute coronary syndrome, heart muscle disease, pulmonary embolism, pulmonary hypertension, sepsis, stroke, cardiotoxic drugs, and renal dysfunction.
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The sponsor included the following statement in their instructions for use concerning the performance of their device in outpatient settings:
This test has very low positive predictive value (PPV) in an outpatient population (<23%). In the study, >77% of patients with a positive result did not have an adjudicated diagnosis of HF (false positives).
## E Expected Values/Reference Range:
The reference interval was conducted in accordance with the CLSI EP28 guidance. The VITROS® NT-proBNP II Reagent Pack reference interval (RI) was established for six subgroups, based on age and gender from the serum of 385 female and 374 male healthy donors. The exclusion criteria used to exclude subjects were:
- Current smokers, subjects with cardiac conditions and disease, high blood pressure, kidney disease, diabetes, cancer within the last five years, stroke, and asthma or other lung disease within the last five years.
- Subjects who have reported high cholesterol, high triglycerides, thyroid disease, and females who are pregnant.
- Additional exclusion criteria:
a. Troponin ≥ 99th percentile (≥ 0.034 ng/mL - VITROS Troponin I ES assay)
b. HbA1c ≥ 6.5%
c. Creatinine (eGFR ≤ 60 mL/min)
Analysis at the 95% confidence level yields the reference ranges shown in the table.
| Age | Gender | N | Reference interval lower limit (pg/mL) | Reference interval upper limit (pg/mL) |
| --- | --- | --- | --- | --- |
| 22 – <50 | Female | 129 | <20.0 | 95.3 |
| 50 – <75 | Female | 127 | <20.0 | 221 |
| ≥75 | Female | 129 | <20.0 | 296 |
| 22 – <50 | Male | 131 | <20.0 | 125 |
| 50 – <75 | Male | 120 | <20.0 | 299 |
| ≥75 | Male | 123 | <20.0 | 326 |
| Overall | | 756 | <20.0 | 217 |
## VIII Proposed Labeling:
The labeling supports the finding of substantial equivalence for this device.
## IX Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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