Alere NT-proBNP for Alinity i Reagent Kit
Device Facts
| Record ID | K241176 |
|---|---|
| Device Name | Alere NT-proBNP for Alinity i Reagent Kit |
| Applicant | Axis-Shield Diagnostics, Ltd. |
| Product Code | NBC · Clinical Chemistry |
| Decision Date | Jan 16, 2025 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 862.1117 |
| Device Class | Class 2 |
Intended Use
The Alere NT-proBNP for Alinity i assay is a chemiluminescent microparticle immunoassay (CMIA) used for the in vitro quantitative determination of N-terminal pro B-type natriuretic peptide (NT-proBNP) in human serum and plasma on the Alinity i system. In the emergency department, measurements of NT-proBNP are used as an aid in the diagnosis of heart failure (HF) in patients with clinical suspicion of new onset or worsening HF.
Device Story
The Alere NT-proBNP for Alinity i is an automated, two-step chemiluminescent microparticle immunoassay (CMIA) for quantitative determination of NT-proBNP in human serum and plasma. The device uses anti-NT-proBNP coated paramagnetic microparticles and acridinium-labeled conjugate. The system measures the resulting chemiluminescent reaction as relative light units (RLU), which are directly proportional to NT-proBNP concentration. Used in emergency departments, the device provides results that clinicians interpret alongside patient history and clinical examination to aid in diagnosing heart failure. The device helps differentiate between heart failure and other causes of dyspnea, potentially improving diagnostic accuracy and patient management in acute settings.
Clinical Evidence
Prospective multi-center study of 2127 ED subjects (18+ years) with suspected heart failure. Adjudication by 10 board-certified cardiologists. Performance evaluated using age-dependent positive cutoffs and age-independent negative cutoff. Results provided for all subjects, sex, age groups, and comorbidities (e.g., eGFR, BMI, history of HF). Sensitivity/specificity metrics derived from likelihood ratios and posttest probabilities. Study established clinical utility for aiding HF diagnosis.
Technological Characteristics
CMIA technology; reagents include anti-NT-proBNP (sheep, monoclonal) coated microparticles and anti-NT-proBNP (mouse, monoclonal) acridinium-labeled conjugate. Measuring interval: 15.8 to 35,000 pg/mL (extended to 350,000 pg/mL via dilution). Automated system (Alinity i). Standards referenced: CLSI EP05-A3, EP06, EP07, EP12, EP17-A2, EP28-A3c, EP34, EP35.
Indications for Use
Indicated for use in emergency departments as an aid in the diagnosis of heart failure (HF) in patients (18+ years) with clinical suspicion of new onset or worsening HF. Not indicated for patients with renal insufficiency requiring dialysis or known eGFR < 15.0 mL/min/1.73 m².
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 (K092649)
Related Devices
- K220265 — ADVIA Centaur® NT-proBNPII (PBNPII) · Siemens Healthcare Diagnostics, Inc. · Sep 24, 2023
- K232164 — Access NT-proBNP · Beckman Coulter, Inc. · Apr 12, 2024
- K253539 — Alere NT-proBNP for Alinity i · Axis-Shield Diagnostics, Ltd. · Feb 18, 2026
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
K241176
B Applicant
Axis-Shield Diagnostics Ltd
C Proprietary and Established Names
Alere NT-proBNP for Alinity i
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:
NT-proBNP
C Type of Test:
Quantitative 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:
The Alere NT-proBNP for Alinity i assay is a chemiluminescent microparticle immunoassay (CMIA) used for the in vitro quantitative determination of N-terminal pro B-type natriuretic peptide (NT-proBNP) in human serum and plasma on the Alinity i system.
In the emergency department, measurements of NT-proBNP are used as an aid in the diagnosis of heart failure (HF) in patients with clinical suspicion of new onset or worsening HF.
C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only
D Special Instrument Requirements:
Alinity i system
IV Device/System Characteristics:
A Device Description:
The Alere NT-proBNP for Alinity i assay is an automated, two-step immunoassay for the in vitro quantitative determination of NT-proBNP in human serum and plasma (using chemiluminescent microparticle immunoassay (CMIA) technology.
Reagents:
Microparticles: Anti-NT-proBNP (sheep, monoclonal) coated microparticles in Bis-TRIS buffer with protein (bovine) stabilizer, non-specific binding blocking agents, and surfactant. Minimum concentration: 0.05 % solids. Preservative: sodium azide.
Conjugate: Anti-NT-proBNP (mouse, monoclonal) acridinium labeled conjugate in MES buffer with protein (bovine) stabilizer and surfactant. Minimum concentration: 0.12 µg/mL.
Preservatives: antimicrobial agents.
Materials required but not supplied with the reagent kit include Alere NT-proBNP for Alinity i calibrators and quality controls, Alinity pre-trigger and trigger solution, Alinity-i series concentrated wash buffer and Alinity i multi-assay manual diluent.
B Principle of Operation:
Sample and anti-NT-proBNP coated paramagnetic microparticles are combined and incubated. The NT-proBNP present in the sample binds to the anti-NT-proBNP coated microparticles. The mixture is washed. Anti-NT-proBNP acridinium-labeled conjugate is added to create a reaction mixture and incubated. Following a wash cycle, Pre-Trigger and Trigger Solutions are added.
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The resulting chemiluminescent reaction is measured as a relative light unit (RLU). There is a direct relationship between the amount of NT-proBNP in the sample and the RLU detected by the system optics.
# V Substantial Equivalence Information:
A Predicate Device Name(s):
Elecsys ProBNP II Stat Immunoassay
B Predicate 510(k) Number(s):
K092649
C Comparison with Predicate(s):
| Device & Predicate Device(s): | K241176 | K092649 |
| --- | --- | --- |
| Device Trade Name | Alere NT-proBNP for Alinity i | Elecsys proBNP II STAT Immunoassay |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | Immunoassay used for the in vitro quantitative determination of N-terminal pro B-type natriuretic peptide (NT-proBNP) in human serum and plasma. This assay is to be used as an aid in the diagnosis of individuals suspected of having congestive heart failure (CHF). | Same |
| Specimen Type | Human serum and plasma | Same |
| Test principle | Sandwich immunoassay | Same |
| Measurement type | Quantitative | Same |
| Detection Technology | Chemiluminescence | Same |
| General Device Characteristic Differences | | |
| Principle of Operation | Chemiluminescent microparticle immunoassay (CMIA) | Electro chemiluminescent microparticle immunoassay (ECLIA) |
| Results Interpretation | Negative: HF unlikely for all patients: < 300.0 pg/mL Gray Zone: Indeterminate; consider other causes of NT- | 125 pg/mL for < 75 years 450 pg/mL for ≥ 75 years |
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| Device & Predicate Device(s): | K241176 | K092649 |
| --- | --- | --- |
| | proBNP elevation:
Age (Years) NT-proBNP (pg/mL)
18 to < 50 ≥ 300.0 to < 450.0
50 to 75 ≥ 300.0 to < 900.0
> 75 ≥ 300.0 to < 1800.0
Positive: HF likely:
Age (Years) NT-proBNP (pg/mL)
18 to < 50 ≥ 450.0
50 to 75 ≥ 900.0
> 75 ≥ 1800.0 | |
| Measuring Interval | 15.8 to 35,000.0 pg/mL | 5 to 35,000 pg/mL |
| Hook Effect | No hook effect up to 372,620 pg/mL | No hook effect up to 300,000 pg/mL |
VI Standards/Guidance Documents Referenced:
CLSI EP05-A3: Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline – Third Edition
CLSI EP06: Evaluation of the Linearity of Quantitative Measurement Procedures, 2nd Edition
CLSI EP07: Interference Testing in Clinical Chemistry, 3rd Edition
CLSI EP12: Evaluation of Qualitative, Binary Output Examination Performance, 3rd Edition
CLSI EP17-A2: Evaluation of Detection Capability for Clinical Laboratory Measurement Procedure; Approved Guideline – Second Edition
CLSI EP25: Evaluation of Stability of In Vitro Medical Laboratory Test Reagents, 2nd Edition
CLSI EP28-A3c: Defining Establishing and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline - Third Edition
CLSI EP34: Establishing and Verifying an Extended Measuring Interval Through Specimen Dilution and Spiking, 1st Edition
CLSI EP35: Assessment of Equivalence or Suitability of Specimen Types for Medical Laboratory Measurement Procedures. 1st Edition
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VII Performance Characteristics (if/when applicable):
A Analytical Performance:
1. Precision/Reproducibility:
Within-Laboratory Precision (20-Day)
A study was performed based on guidance from CLSI EP05-A3.
Three controls and 8 human plasma panels (7 native panels and 1 panel supplemented with NT-proBNP analyte) were tested in 2 replicates at 2 separate times per day over 20 days (for a total of 80 measurements per sample). Testing was conducted using 3 lots of the candidate device, 1 lot of the Alere NT-proBNP for Alinity i Calibrators, 1 lot of the Alere NT-proBNP for Alinity i Controls, and 1 Alinity i instrument.
Panels (Panel A to Panel G) were prepared by pooling NT-proBNP K₂EDTA plasma specimens and diluting with human K₂EDTA plasma as necessary to achieve the target concentrations. Panel H was prepared by spiking K₂EDTA plasma with a synthetic NT-proBNP peptide. The sponsor provided evidence to show that the contrived samples mimic patient samples.
Results are summarized in the table below:
| Sample | N | Mean (pg/mL) | Repeatability (Within-Run) | | Within-Laboratory^a | | Between-Lot | | Overall Within-Laboratory^b | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low Control | 240 | 143.0 | 6.40 | 4.5 | 7.63 | 5.3 | 4.42 | 3.1 | 8.82 | 6.2 |
| Medium Control | 240 | 503.4 | 16.26 | 3.2 | 18.21 | 3.6 | 9.29 | 1.8 | 20.44 | 4.1 |
| High Control | 240 | 5144.2 | 177.02 | 3.4 | 202.18 | 3.9 | 21.47 | 0.4 | 203.32 | 4.0 |
| Panel A | 240 | 18.8 | 1.39 | 7.4 | 1.72 | 9.2 | 0.75 | 4.0 | 1.88 | 10.0 |
| Panel B | 240 | 55.6 | 2.64 | 4.7 | 3.02 | 5.4 | 1.60 | 2.9 | 3.41 | 6.1 |
| Panel C | 240 | 130.4 | 4.28 | 3.3 | 5.44 | 4.2 | 4.87 | 3.7 | 7.30 | 5.6 |
| Panel D | 240 | 449.1 | 13.10 | 2.9 | 18.68 | 4.2 | 14.02 | 3.1 | 23.36 | 5.2 |
| Panel E | 240 | 1011.4 | 28.31 | 2.8 | 34.49 | 3.4 | 21.92 | 2.2 | 40.87 | 4.0 |
| Panel F | 240 | 1938.0 | 54.02 | 2.8 | 65.28 | 3.4 | 22.56 | 1.2 | 69.07 | 3.6 |
| Panel G | 240 | 14939.8 | 417.56 | 2.8 | 518.88 | 3.5 | 296.61 | 2.0 | 597.67 | 4.0 |
| Panel H | 240 | 31711.0 | 989.02 | 3.1 | 1185.11 | 3.7 | 2118.19 | 6.7 | 2427.19 | 7.7 |
<a>^a</a>Includes repeatability (within-run), between-run, and between-day variability
<a>^b</a>Includes repeatability (within-run), between-run, between-day, and between-lot variability
Reproducibility
A study was performed based on guidance from CLSI EP05-A3.
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Testing was conducted at 3 sites, using 3 lots of the candidate device, 2 lots of the Alere NT-proBNP for Alinity i Calibrators, 2 lots of the Alere NT-proBNP for Alinity i Controls, and 1 Alinity i instrument.
Three controls and 8 reproducibility panel plasma members were tested in 4 replicates at 2 separate times per day on 5 different days.
The native panel members 1 to 6 were prepared by pooling NT-proBNP K₂EDTA plasma specimens and diluting with human K₂EDTA plasma as necessary to achieve the target concentration. Panel 7 and Panel 8 were prepared by spiking K₂EDTA plasma with a synthetic NT-proBNP peptide. Results are summarized in the table below:
| Sample | N | Mean (pg/mL) | Repeatability | | Within-Laboratory1 | | Between-Site | | Between-Lot | | Overall Reproducibility | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | SD | %CV | SD | %CV | SD | %CV | SD | %CV | SD | %CV |
| Low Control | 360 | 136.6 | 4.75 | 3.5 | 5.75 | 4.2 | 2.63 | 1.9 | 1.45 | 1.1 | 6.49 | 4.7 |
| Medium Control | 360 | 477.1 | 12.24 | 2.6 | 15.35 | 3.2 | 14.20 | 3.0 | 8.88 | 1.9 | 22.72 | 4.8 |
| High Control | 359 | 4932.2 | 201.01 | 4.1 | 311.08 | 6.3 | 105.17 | 2.1 | 0.00 | 0.0 | 328.38 | 6.7 |
| Panel 1 | 359 | 14.5 | 2.10 | 14.5 | 2.74 | 18.9 | 0.00 | 0.0 | 0.00 | 0.0 | 2.74 | 18.9 |
| Panel 2 | 360 | 51.9 | 2.14 | 4.1 | 3.07 | 5.9 | 0.49 | 0.9 | 0.00 | 0.0 | 3.11 | 6.0 |
| Panel 3 | 360 | 127.1 | 4.67 | 3.7 | 5.95 | 4.7 | 1.36 | 1.1 | 0.78 | 0.6 | 6.15 | 4.8 |
| Panel 4 | 360 | 436.9 | 10.46 | 2.4 | 18.67 | 4.3 | 3.18 | 0.7 | 0.00 | 0.0 | 18.94 | 4.3 |
| Panel 5 | 360 | 996.5 | 21.86 | 2.2 | 43.45 | 4.4 | 17.12 | 1.7 | 0.00 | 0.0 | 46.70 | 4.7 |
| Panel 6 | 360 | 1891.1 | 33.18 | 1.8 | 79.86 | 4.2 | 35.96 | 1.9 | 0.00 | 0.0 | 87.58 | 4.6 |
| Panel 7 | 359 | 15664.6 | 319.91 | 2.0 | 974.61 | 6.2 | 281.81 | 1.8 | 217.28 | 1.4 | 1037.54 | 6.6 |
| Panel 8 | 360 | 25630.5 | 601.42 | 2.3 | 1654.86 | 6.5 | 220.39 | 0.9 | 807.19 | 3.1 | 1854.37 | 7.2 |
<a>1</a> Includes repeatability, between-run, and between-day variance components
<a>2</a> Includes repeatability, between-run, between-day, between-site, and between-lot variance components
<a>3</a> An outlying run was observed. Based on guidance from CLSI EP05-A3, a replacement run was performed. Without the replacement run, the repeatability SD was 9.53 pg/mL (1.12 pmol/L), within-laboratory SD was 9.64 pg/mL (1.14 pmol/L), and the overall reproducibility SD was 9.64 pg/mL (1.14 pmol/L).
2. Linearity:
A linearity study was performed based on guidance from CLSI EP06, 2nd ed.
Two linearity K₂EDTA plasma sample sets were prepared, each containing 8-9 concentration levels. Each linearity panel was a dilution series prepared by intermixing known volumes of high native sample with analyte-free plasma. The samples were tested in replicates of 10 using 3 reagent lots, 1 calibrator lot, 1 control lot, and 1 Alinity i instrument. All samples within the sample set were tested within a single run.
The linearity was analyzed separately for each reagent lot per sample type. Using a weighted linear regression analysis, the difference and percent difference between the mean observed
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concentration and the expected concentration of each sample were calculated. At each concentration, the deviation from linearity was less than 11.3%.
The results of the linearity study support the claimed measuring range of 15.8 to 35,000.0 pg/mL.
## Sample Dilution
Plasma samples with NT-proBNP concentrations up to 70,000 pg/mL can be measured after a 1:2 auto dilution, and samples with NT-proBNP concentrations up to 350,000 pg/mL can be measured using a 1:10 manual dilution. The percent recovery of diluted samples ranged from 92.1% to 103.4%.
## 3. Analytical Specificity/Interference:
Interference studies were performed based on guidance from CLSI EP07, 3rd ed.
## Endogenous Substances
Interference from endogenous substances was assessed using K₂EDTA plasma samples at two levels of NT-proBNP analyte (approximately 125 pg/mL and 2000 pg/mL). Each sample was divided into 2 aliquots: one aliquot for the test sample (with added interferent) and one aliquot for the control sample (without added interferent). Each sample was tested in replicates of 30 using one Alinity i Analyzer, three reagent lots, and one calibrator lot.
No significant interference (defined by the sponsor as a difference within ± 10% between the mean for the test sample versus the mean of the reference samples) was observed at the following concentrations:
| Potentially Interfering Substance | Highest concentration tested at which no significant interference is observed |
| --- | --- |
| Bilirubin (conjugated) | 60 mg/dL |
| Bilirubin (unconjugated) | 60 mg/dL |
| Biotin | 4250 ng/mL |
| Cholesterol | 700 mg/dL |
| Human Anti-Mouse Antibodies (HAMA) | 1500 ng/mL |
| Hemoglobin | 1 g/dL |
| IgG | 6 g/dL |
| Intralipid | 3000 mg/dL |
| Rheumatoid Factor (RF) | 600 IU/mL |
| Total Protein | 12.6 g/dL |
Interference beyond ± 10.0% (based on 95% Confidence Interval [CI]) was observed at the concentrations shown below for the following substances.
| Potentially Interfering Substance | Interferent Level | Analyte Level | % Interference (95% CI) |
| --- | --- | --- | --- |
| RF | 1520 IU/mL | 125 pg/mL | -8.9% (-10.4%, -7.5%) |
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| Potentially Interfering Substance | Interferent Level | Analyte Level | % Interference (95% CI) |
| --- | --- | --- | --- |
| | 1520 IU/mL | 2000 pg/mL | -11.4% (-12.4%, -10.4%) |
| Total Protein | 15.2 g/dL | 125 pg/mL | -12.7% (-14.7%, -10.7%) |
| | 15.5 g/dL | 2000 pg/mL | -9.9% (-11.4%, -8.5%) |
## Potentially Interfering Drugs
Interference from exogenous substances was assessed using K₂EDTA plasma samples at two levels of the NT-proBNP analyte (approximately 125 pg/mL and 2000 pg/mL), following the same procedure as for endogenous substances.
No significant interference (defined by the sponsor as a difference within ± 10% between the mean for the test sample versus the mean of the reference samples) was observed at the following concentrations:
| Potentially Interfering Drug | Highest concentration tested at which no significant interference is observed |
| --- | --- |
| Acetaminophen | 15.6 mg/dL |
| Acetylsalicylic Acid | 60 mg/dL |
| Allopurinol | 6.0 mg/dL |
| Amikacin | 15 mg/dL |
| Amiodarone | 4.2 mg/dL |
| Amlodipine Besylate | 0.4 mg/dL |
| Ampicillin | 7.5 mg/dL |
| Ascorbic acid | 5.25 mg/dL |
| Atenolol | 1.0 mg/dL |
| Atorvastatin | 32 mg/dL |
| Caffeine | 10.8 mg/dL |
| Captopril | 5.0 mg/dL |
| Carbamazepine | 4.5 mg/dL |
| Carvedilol | 3.75 mg/dL |
| Chloramphenicol | 7.8 mg/dL |
| Chlordiazepoxide | 1.0 mg/dL |
| Chlorpromazine | 0.33 mg/dL |
| Cimetidine | 3.0 mg/dL |
| Cinnarizine | 3.1 mg/dL |
| Clopidogrel bisulfate | 7.5 mg/dL |
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| Potentially Interfering Drug | Highest concentration tested at which no significant interference is observed |
| --- | --- |
| Creatinine | 30 mg/dL |
| Cyclosporine A | 0.4 mg/dL |
| Dextran 40 | 6000 mg/dL |
| Diazepam | 3.0 mg/dL |
| Diclofenac | 6.0 mg/dL |
| Digoxin | 0.025 mg/dL |
| Diltiazem | 12 mg/dL |
| Dipyridamole | 8.0 mg/dL |
| Disopyramide | 4.0 mg/dL |
| Dobutamine | 10 mg/dL |
| Dopamine | 65 mg/dL |
| Enalapril Maleate | 1.6 mg/dL |
| Epinephrine | 0.05 mg/dL |
| Erythromycin | 13.8 mg/dL |
| Ethanol | 600 mg/dL |
| Ethosuximide | 30 mg/dL |
| Fenofibrate | 4.5 mg/dL |
| Furosemide | 6.0 mg/dL |
| Gentamicin | 12 mg/dL |
| Heparin | 8 U/mL |
| Hydralazine | 2.0 mg/dL |
| Hydrochlorothiazide | 2.0 mg/dL |
| Insulin | 0.16 mg/dL |
| Ibuprofen | 50 mg/dL |
| Indomethacin | 3.6 mg/dL |
| Isosorbide dinitrate | 6.0 mg/dL |
| Lidocaine | 8.0 mg/dL |
| Lisinopril | 1.6 mg/dL |
| Lithium | 4.20 mg/dL |
| Losartan potassium | 5.99 mg/dL |
| Lovastatin | 2.0 mg/dL |
| L-Thyroxine | 0.06 mg/dL |
| Methyldopa | 2.5 mg/dL |
| Methylprednisolone | 0.75 mg/dL |
| Metoprolol | 1.5 mg/dL |
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| Potentially Interfering Drug | Highest concentration tested at which no significant interference is observed |
| --- | --- |
| Milrinone | 0.183 mg/dL |
| Naproxen | 49.97 mg/dL |
| Nicotine | 0.1 mg/dL |
| Nicotinic acid | 4.0 mg/dL |
| Nifedipine | 6.0 mg/dL |
| Nitrofurantoin | 4.0 mg/dL |
| Nitroglycerin | 0.016 mg/dL |
| Oxazepam | 1.2 mg/dL |
| Oxytetracycline | 10 mg/dL |
| Penicillin G | 25 U/mL |
| Pentobarbital | 12.6 mg/dL |
| Phenobarbitol | 69 mg/dL |
| Phenprocoumon (Marcumar) | 1.53 mg/dL |
| Phenytoin | 6.0 mg/dL |
| Primidone | 5.7 mg/dL |
| Probenecid | 60 mg/dL |
| Procainamide | 4.8 mg/dL |
| Propafenone | 30 mg/dL |
| Propanolol | 0.2 mg/dL |
| Propoxyphene | 0.321 mg/dL |
| Quinidine | 2.0 mg/dL |
| Ramipril | 0.6 mg/dL |
| Retaplase | 3.33 mg/dL |
| Simvastatin | 3.2 mg/dL |
| Spironolactone | 7.5 mg/dL |
| Sulfamethoxazole | 112 mg/dL |
| Theophylline | 6.0 mg/dL |
| Tolbutamide | 150 mg/dL |
| Torasemide | 1.5 mg/dL |
| Trandolapril | 4.0 mg/dL |
| Trasylol/Aprotinin | 501.8 KIE/mL |
| Trimethoprim | 6.4 mg/dL |
| Uric Acid | 23.5 mg/dL |
| Valproic Acid | 50 mg/dL |
| Verapamil | 24 mg/dL |
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| Potentially Interfering Drug | Highest concentration tested at which no significant interference is observed |
| --- | --- |
| Warfarin | 7.5 mg/dL |
## Cross-Reactants
A study was conducted to evaluate the performance of the Alere NT-proBNP for Alinity i assay in the presence of potential cross-reactants.
Testing was conducted using K₂EDTA samples at two levels of NT-proBNP (125 pg/mL and 2000 pg/mL). Each sample was divided into 2 aliquots: one aliquot for the test sample (spiked with cross-reactant) and one aliquot for the control sample (spiked with the same diluent used for the preparation of cross-reactant in stock solutions). Each sample was tested in replicates of 30 using 1 reagent lot, 1 calibrator lot, 1 control lot, and 1 Alinity i instrument.
The % Recovery was calculated as:
$$
\% \text{Recovery} = 100 \times (\text{test mean} / \text{control mean})
$$
The observed % recovery of NT-proBNP was within $100\% \pm 10\%$ for all cross-reactants evaluated at each analyte level:
| Potential Cross-Reactant | Cross-Reactant Concentration |
| --- | --- |
| Adrenomedullin | 1000 pg/mL |
| Aldosterone | 600 pg/mL |
| Angiotensin I | 600 pg/mL |
| Angiotensin II | 600 pg/mL |
| Angiotensin III | 1000 pg /mL |
| ANP 28 | 3100 ng/mL |
| Arg-Vasopressin | 1000 pg/mL |
| BNP 32 | 3500 ng/mL |
| CNP 22 | 2200 ng/mL |
| Endothelin | 20 pg/mL |
| NT-proANP 1-30 (preproANP26-55) | 3500 ng/mL |
| NT-proANP 31-67 (preproANP56-92) | 1000 pg/mL |
| NT-proANP 79-98 (preproANP104-123) | 1000 pg/mL |
| Renin | 50 000 pg/mL |
| Urodilatin | 3500 ng/mL |
## High Dose Hook Effect
The Alere NT-proBNP for Alinity i assay was evaluated for high dose hook effect using K₂EDTA plasma samples with 4 concentration levels of NT-proBNP. No high dose hook effect was observed on samples up to 372,620 pg/mL of NT-proBNP.
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4. Assay Reportable Range:
The analytical measuring interval (AMI) for the Alere NT-proBNP for Alinity i assay was determined to be from 15.8 to 35,000.0 pg/mL.
The extended measuring interval (EMI) for the Alere NT-proBNP for Alinity i assay was determined to be from 35,000.0 to 350,000.0 pg/mL.
The reportable interval for the Alere NT-proBNP for Alinity i assay was determined to be from 15.8 to 350,000.0 pg/mL.
5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
Traceability
The Alere NT-proBNP for Alinity i Calibrators are traceable to internal reference standards at every concentration level that were value assigned on and made traceable to the predicate device by transference, as described by CLSI Document EP32-R.
Specimen Stability
Specimen storage times were validated with serum separator and K₂EDTA plasma tube types. The sponsor has provided information to support the following claims in their labeling:
| Specimen Type | Temperature | Maximum Storage Time | Special Instructions |
| --- | --- | --- | --- |
| Serum/Plasma | Room temperature (20 to 25°C) | 48 hours | Remove serum or plasma from the clot, red blood cells, or separator gel if testing will be delayed more than 24 hours. |
| | 2 to 8°C | 3 days | Remove serum or plasma from the clot, red blood cells, or separator gel if testing will be delayed more than 24 hours. |
| | -20°C or colder | 30 days | Remove serum or plasma from the clot, red blood cells, or separator gel. |
Avoid more than 3 freeze/thaw cycles.
Sample Onboard Storage
The sponsor provided data to support that samples can be stored on the Alinity i system for up to 3 hours when tested with the Alere NT-proBNP for Alinity i assay.
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6. Detection Limit:
The LoB, LoD, and LoQ study was performed based on guidance from CLSI EP17-A2.
Limit of Blank (LoB)
The LoB study was performed on 4 analyte-free K₂EDTA plasma specimens, using 3 reagent lots, 1 calibrator lot, 1 control lot, and 2 Alinity i instruments. Testing occurred over 3 days. Samples were tested in 5 replicates on each day of testing, for a total of 60 replicates. The LoB was determined non-parametrically for each reagent lot separately and the highest value obtained from three lots was taken as the LoB value. The LoB for the Alere NT-proBNP for Alinity i assay was estimated to be 0.1 pg/mL.
Limit of Detection (LoD)
The LoD study was performed on 18 low-level panels (2 samples at each of 9 unique target concentration levels of approximately 3.0, 4.0, 5.0, 7.0, 9.0, 12.0, 16.0, 20.0, and 24.0 pg/mL), using 3 reagent lots, 1 calibrator lot, 1 control lot, and 2 Alinity i instruments. Testing occurred over 3 days. The 18 low-analyte samples were tested in 10 replicates on each day of testing, for a total of 60 measurements per sample per reagent lot. The parametric approach described in CLSI EP17-A2 was followed to determine the LoD. The highest observed LoD of the three lots was the reported LoD for the assay. The LoD for the Alere NT-proBNP for Alinity i assay was estimated to be 3.6 pg/mL.
Limit of Detection (LoQ)
The LoQ study was performed on 18 low-level panels (2 samples at each of 9 unique target concentration levels of approximately 3.0, 4.0, 5.0, 7.0, 9.0, 12.0, 16.0, 20.0, and 24.0 pg/mL), using 3 reagent lots, 1 calibrator lot, 1 control lot, and 2 Alinity i instruments. Testing occurred over 3 days. The 18 low-analyte samples were tested in 10 replicates on each day of testing, for a total of 60 measurements per sample per reagent lot. The LoQ was determined as the lowest concentration of analyte at which the maximum allowable precision of 20% CV was met. The highest value obtained from three lots was the reported LoQ for the assay. The LoQ for the Alere NT-proBNP for Alinity i assay was estimated to be 15.8 pg/mL.
7. Assay Cut-Off:
See Section VII.D for Clinical Cut-off information.
B Comparison Studies:
1. Method Comparison with Predicate Device:
Not applicable.
2. Matrix Comparison:
A study was conducted to evaluate equivalence between different blood collection tubes. The study was performed based on guidance from the CLSI document EP35 1st ed.
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In the study, samples were collected from 63 subjects, representative of the intended use population. A primary tube (control condition, $\mathrm{K}_2\mathrm{EDTA}$ ) and a minimum of 1 candidate tube (test condition) were collected from each enrolled subject. Testing of specimens collected in different tube types was initiated within 2 hours of draw. Two replicates from each specimen tube type were tested. Testing was conducted using 2 Alinity i instruments, 2 reagent lots, 3 calibrator lots, and 3 control lots.
The results were analyzed using Passing-Bablok regression analysis comparing the first replicate of the evaluation tube to the first replicate of the control tube (K2EDTA).
| Tube Type | N | Concentration Range (pg/mL) | Slope | Intercept | r |
| --- | --- | --- | --- | --- | --- |
| K3EDTA | 60 | 20.2-29670.1 | 0.98 | 1.1 | 0.999 |
| Serum | 56 | 20.2-19929.3 | 1.02 | 1.6 | 0.993 |
| Serum Separator Tube | 57 | 21.8-29670.1 | 1.00 | 1.0 | 0.999 |
| Lithium Heparin | 61 | 20.2-29670.1 | 1.00 | 0.1 | 0.998 |
| Lithium Heparin (Plasma Separator) | 57 | 20.2-29670.1 | 0.99 | -1.2 | 1.000 |
The study results demonstrate equivalence between $\mathrm{K}_2\mathrm{EDTA}$ plasma, $\mathrm{K}_3\mathrm{EDTA}$ plasma, lithium heparin plasma, and serum samples.
# C Clinical Studies:
1. Clinical Sensitivity:
Not applicable.
2. Clinical Specificity:
Not applicable.
3. Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):
A multi-center prospective study including 17 collection sites across the US was conducted to establish the performance characteristics of the Alere NT-proBNP for Alinity i assay. Subjects 18 years and older presenting to the emergency department (ED) with signs and symptoms consistent with a clinical suspicion of new onset or acute exacerbation of HF were included in the study. Subjects with renal insufficiency requiring dialysis or known estimated glomerular filtration rate (eGFR) $< 15\mathrm{mL / min} / 1.73\mathrm{m}^2$ and subjects with dyspnea after chest trauma were excluded from the study. For each patient enrollment, whole blood samples
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were collected in $\mathrm{K}_2\mathrm{EDTA}$ tubes, processed to plasma, and stored frozen until testing. Data supporting the stability of the samples for the storage time and condition were provided by the sponsor.
The results were determined from 2127 ED subjects. Of the 2127 ED subjects, 1030 (48.4%) were female and 1097 (51.6%) were male, ranging in age from 19 to 97 years. Individuals in the population were White (53.1%), Black or African American (39.45%), Asian (1.7%), American Indian or Alaska Native (0.8%), Native Hawaiian or Other Pacific Islander (0.3%), or represented by other races (0.9%), with the remaining 3.6% of Unknown / Not Reported race. A total of 1934 (90.9%) ED subjects were not Hispanic or Latino, and 168 (7.9%) ED subjects were Hispanic or Latino, with the remaining 25 (1.2%) ED subjects of Unknown / Not Reported ethnicity.
The clinical study specimen testing was performed with clinical specimens that were randomly distributed across 3 clinical testing sites using 3 lots of the Alere NT-proBNP for Alinity i Reagents, 2 lots of the Alere NT-proBNP for Alinity i Calibrators, 2 lots of the Alere NT-proBNP for Alinity i Controls, and 1 Alinity i instrument at each clinical site. One replicate of each specimen was tested with the investigational device.
Adjudication was performed by a panel of 10 board-certified cardiologists. A determination of HF (acute exacerbation or new onset) or non-HF was rendered for each subject. The adjudicators were blinded to the diagnosis and HF severity of the local attending physician in the ED, and the determination of other members of the adjudication panel. For subjects determined to have HF, severity was assessed based on New York Heart Association (NYHA) classification (I, II, III, IV) and a determination of new or worsening HF.
The descriptive statistics for the Alere NT-proBNP for Alinity i test results $(\mathrm{pg / mL})$ were determined within and across sex by age group and are summarized in the following table:
Alere NT-proBNP for Alinity i - All Subjects
| Adjudicated Diagnosis | HF | | | | Non-HF | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age Group (Years) | <50 | 50 to 75 | >75 | All | <50 | 50 to 75 | >75 | All |
| N | 160 | 553 | 167 | 880 | 300 | 799 | 148 | 1247 |
| Mean | 4354.5 | 6092.9 | 6891.3 | 5928.3 | 437.9 | 760.4 | 1738.8 | 798.9 |
| SD | 5454.61 | 8144.69 | 6860.32 | 7521.45 | 1686.57 | 1833.48 | 3494.96 | 2100.93 |
| Median | 2664.9 | 3297.2 | 4787.6 | 3420.7 | 70.1 | 198.9 | 565.9 | 181.8 |
| Minimum | 22.8 | 19.8 | 158.9 | 19.8 | 0.0 | 0.0 | 4.2 | 0.0 |
| Maximum | 38880.9 | 60716.9 | 38938.4 | 60716.9 | 24737.1 | 17988.9 | 31154.0 | 31154.0 |
Alere NT-proBNP for Alinity i - Male Subjects
| Adjudicated Diagnosis | HF | | | | Non-HF | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age Group (Years) | <50 | 50 to 75 | >75 | All | <50 | 50 to 75 | >75 | All |
| N | 105 | 317 | 82 | 504 | 135 | 392 | 66 | 593 |
| Mean | 4354.5 | 6092.9 | 6891.3 | 5928.3 | 437.9 | 760.4 | 1738.8 | 798.9 |
| SD | 5454.61 | 8144.69 | 6860.32 | 7521.45 | 1686.57 | 1833.48 | 3494.96 | 2100.93 |
| Median | 2664.9 | 3297.2 | 4787.6 | 3420.7 | 70.1 | 198.9 | 565.9 | 181.8 |
| Minimum | 22.8 | 19.8 | 158.9 | 19.8 | 0.0 | 0.0 | 4.2 | 0.0 |
| Maximum | 38880.9 | 60716.9 | 38938.4 | 60716.9 | 24737.1 | 17988.9 | 31154.0 | 31154.0 |
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| Mean | 4522.0 | 6631.0 | 6971.2 | 6247.0 | 638.8 | 911.6 | 2258.0 | 999.4 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| SD | 4977.78 | 8410.52 | 6708.84 | 7590.10 | 2369.85 | 2084.06 | 4464.35 | 2557.26 |
| Median | 2780.1 | 4066.5 | 4773.9 | 3904.3 | 64.1 | 221.0 | 701.8 | 203.2 |
| Min | 58.3 | 19.8 | 186.9 | 19.8 | 0.0 | 0.0 | 4.2 | 0.0 |
| Max | 26986.3 | 60716.9 | 32286.4 | 60716.9 | 24737.1 | 17988.9 | 31154.0 | 31154.0 |
Alere NT-proBNP for Alinity i - Female Subjects
| Adjudicated Diagnosis | HF | | | | Non-HF | | | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Age Group (Years) | <50 | 50 to 75 | >75 | All | <50 | 50 to 75 | >75 | All |
| N | 55 | 236 | 85 | 376 | 165 | 407 | 82 | 654 |
| Mean | 4034.7 | 5370.1 | 6814.2 | 5501.2 | 273.5 | 614.8 | 1320.8 | 617.2 |
| SD | 6302.82 | 7732.10 | 7042.32 | 7417.01 | 732.64 | 1543.13 | 2403.63 | 1556.92 |
| Median | 1851.5 | 2541.7 | 4787.6 | 2786.4 | 73.1 | 174.9 | 499.7 | 161.2 |
| Min | 22.8 | 24.9 | 158.9 | 22.8 | 0.0 | 0.9 | 25.7 | 0.0 |
| Max | 38880.9 | 47385.1 | 38938.4 | 47385.1 | 5633.9 | 14849.5 | 18827.7 | 18827.7 |
For the 2127 subjects enrolled in the study, a total of 880 subjects were adjudicated as subjects with HF and 1247 subjects were adjudicated as subjects without HF.
| | Subject with Heart Failure | Subject without Heart Failure |
| --- | --- | --- |
| Age Group | | |
| < 50 | 34.8% (160/460) | 65.2% (300/460) |
| 50-75 | 40.9% (553/1352) | 59.1% (799/1352) |
| >75 | 53.0% (167/315) | 47.0% (148/315) |
| | | |
| Sex | | |
| Female | 36.5% (376/1030) | 63.5% (654/1030) |
| Male | 45.9% (504/1097) | 54.1% (593/1097) |
The pretest probability of adjudicated HF (prevalence of adjudicated HF in the study), posttest probabilities, and likelihood ratios of the Alere NT-proBNP for Alinity i result vs. adjudicated diagnosis (along with the $95\%$ CIs) were determined based on guidance from CLSI EP12, 3rd ed., for all subjects and by sex using the age-dependent positive cutoffs (450 pg/mL for subjects 18 to $< 50$ years of age, 900 pg/mL for subjects 50 to 75 years of age, and 1800 pg/mL for subjects $>75$ years of age) and age-independent negative cutoff (300 pg/mL).
The results for all subjects are presented in the following tables:
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Clinical Performance – All Subjects:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 34.78% (160/460) | Positive | 140 | 48 | 188 | 74.5 (140 / 188) (67.8, 80.2) | - | 5.47 (4.19, 7.13) |
| | Gray Zone | 7 | 13 | 20 | 35.0 (7 / 20) (18.1, 56.7) | 65.0 (13 / 20) (43.3, 81.9) | 1.01 (0.41, 2.48) |
| | Negative | 13 | 239 | 252 | - | 94.8 (239 / 252) (91.4, 97.0) | 0.10 (0.06, 0.17) |
| | Total | 160 | 300 | 460 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 40.90% (553/1352) | Positive | 437 | 148 | 585 | 74.7 (437 / 585) (71.0, 78.1) | - | 4.27 (3.67, 4.96) |
| | Gray Zone | 80 | 147 | 227 | 35.2 (80 / 227) (29.3, 41.7) | 64.8 (147 / 227) (58.3, 70.7) | 0.79 (0.61, 1.01) |
| | Negative | 36 | 504 | 540 | - | 93.3 (504 / 540) (90.9, 95.1) | 0.10 (0.07, 0.14) |
| | Total | 553 | 799 | 1352 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 53.02% (167/315) | Positive | 131 | 38 | 169 | 77.5 (131 / 169) (70.6, 83.2) | - | 3.06 (2.30, 4.06) |
| | Gray Zone | 34 | 59 | 93 | 36.6 (34 / 93) (27.5, 46.7) | 63.4 (59 / 93) (53.3, 72.5) | 0.51 (0.36, 0.73) |
| | Negative | 2 | 51 | 53 | - | 96.2 (51 / 53) (87.2, 99.0) | 0.03 (0.01, 0.14) |
| | Total | 167 | 148 | 315 | | | |
| All Subjects Pretest Probability of HF (Prevalence of HF in study): 41.37% (880/2127) | Positive | 708 | 234 | 942 | 75.2 (708 / 942) (72.3, 77.8) | - | 4.29 (3.80, 4.83) |
| | Gray Zone | 121 | 219 | 340 | 35.6 (121 / 340) (30.7, 40.8) | 64.4 (219 / 340) (59.2, 69.3) | 0.78 (0.64, 0.96) |
| | Negative | 51 | 794 | 845 | - | 94.0 (794 / 845) (92.2, 95.4) | 0.09 (0.07, 0.12) |
| | Total | 880 | 1247 | 2127 | | | |
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Clinical Performance – Female Subjects:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 25.00% (55/220) | Positive | 45 | 20 | 65 | 69.2 (45 / 65) (57.2, 79.1) | - | 6.75 (4.39, 10.37) |
| | Gray Zone | 3 | 7 | 10 | 30.0 (3 / 10) (10.8, 60.3) | 70.0 (7 / 10) (39.7, 89.2) | 1.29 (0.34, 4.80) |
| | Negative | 7 | 138 | 145 | - | 95.2 (138 / 145) (90.4, 97.6) | 0.15 (0.08, 0.31) |
| | Total | 55 | 165 | 220 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 36.70% (236/643) | Positive | 173 | 56 | 229 | 75.5 (173 / 229) (69.6, 80.7) | - | 5.33 (4.13, 6.88) |
| | Gray Zone | 35 | 76 | 111 | 31.5 (35 / 111) (23.6, 40.7) | 68.5 (76 / 111) (59.3, 76.4) | 0.79 (0.55, 1.15) |
| | Negative | 28 | 275 | 303 | - | 90.8 (275 / 303) (87.0, 93.5) | 0.18 (0.12, 0.25) |
| | Total | 236 | 407 | 643 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 50.90% (85/167) | Positive | 64 | 19 | 83 | 77.1 (64 / 83) (67.0, 84.8) | - | 3.25 (2.15, 4.91) |
| | Gray Zone | 20 | 34 | 54 | 37.0 (20 / 54) (25.4, 50.4) | 63.0 (34 / 54) (49.6, 74.6) | 0.57 (0.36, 0.90) |
| | Negative | 1 | 29 | 30 | - | 96.7 (29 / 30) (83.3, 99.4) | 0.03 (0.00, 0.24) |
| | Total | 85 | 82 | 167 | | | |
| All Female Subjects Pretest Probability of HF (Prevalence of HF in study): 36.50% (376/1030) | Positive | 282 | 95 | 377 | 74.8 (282 / 377) (70.2, 78.9) | - | 5.16 (4.25, 6.27) |
| | Gray Zone | 58 | 117 | 175 | 33.1 (58 / 175) (26.6, 40.4) | 66.9 (117 / 175) (59.6, 73.4) | 0.86 (0.65, 1.15) |
| | Negative | 36 | 442 | 478 | - | 92.5 (442 / 478) (89.7, 94.5) | 0.14 (0.10, 0.19) |
| | Total | 376 | 654 | 1030 | | | |
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Clinical Performance – Male Subjects:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 43.75% (105/240) | Positive | 95 | 28 | 123 | 77.2 (95 / 123) (69.1, 83.8) | - | 4.36 (3.12, 6.10) |
| | Gray Zone | 4 | 6 | 10 | 40.0 (4 / 10) (16.8, 68.7) | 60.0 (6 / 10) (31.3, 83.2) | 0.86 (0.25, 2.96) |
| | Negative | 6 | 101 | 107 | - | 94.4 (101 / 107) (88.3, 97.4) | 0.08 (0.03, 0.17) |
| | Total | 105 | 135 | 240 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 44.71% (317/709) | Positive | 264 | 92 | 356 | 74.2 (264 / 356) (69.4, 78.4) | - | 3.55 (2.95, 4.27) |
| | Gray Zone | 45 | 71 | 116 | 38.8 (45 / 116) (30.4, 47.9) | 61.2 (71 / 116) (52.1, 69.6) | 0.78 (0.56, 1.10) |
| | Negative | 8 | 229 | 237 | - | 96.6 (229 / 237) (93.5, 98.3) | 0.04 (0.02, 0.09) |
| | Total | 317 | 392 | 709 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 55.41% (82/148) | Positive | 67 | 19 | 86 | 77.9 (67 / 86) (68.1, 85.4) | - | 2.84 (1.92, 4.20) |
| | Gray Zone | 14 | 25 | 39 | 35.9 (14 / 39) (22.7, 51.6) | 64.1 (25 / 39) (48.4, 77.3) | 0.45 (0.26, 0.80) |
| | Negative | 1 | 22 | 23 | - | 95.7 (22 / 23) (79.0, 99.2) | 0.04 (0.01, 0.26) |
| | Total | 82 | 66 | 148 | | | |
| All Male Subjects Pretest Probability of HF (Prevalence of HF in study): 45.94% (504/1097) | Positive | 426 | 139 | 565 | 75.4 (426 / 565) (71.7, 78.8) | - | 3.61 (3.10, 4.19) |
| | Gray Zone | 63 | 102 | 165 | 38.2 (63 / 165) (31.1, 45.8) | 61.8 (102 / 165) (54.2, 68.9) | 0.73 (0.54, 0.97) |
| | Negative | 15 | 352 | 367 | - | 95.9 (352 / 367) (93.4, 97.5) | 0.05 (0.03, 0.08) |
| | Total | 504 | 593 | 1097 | | | |
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The pretest probability of adjudicated HF (prevalence of adjudicated HF in the study), posttest probabilities, and likelihood ratios of the Alere NT-proBNP for Alinity i result vs adjudicated diagnosis (along with the 95% CIs) were also determined for relevant clinical subgroups using the age-dependent positive cutoffs and age-independent negative cutoff.
Clinical Performance – Subjects with History of Heart Failure:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 71.70% (114/159\) | Positive | 103 | 17 | 120 | 85.8 (103 / 120) (78.5, 91.0) | - | 2.39 (1.64, 3.50) |
| | Gray Zone | 5 | 3 | 8 | 62.5 (5 / 8) (30.6, 86.3) | 37.5 (3 / 8) (13.7, 69.4) | 0.66 (0.16, 2.64) |
| | Negative | 6 | 25 | 31 | - | 80.6 (25 / 31) (63.7, 90.8) | 0.09 (0.04, 0.22) |
| | Total | 114 | 45 | 159 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 65.09% (427/656) | Positive | 344 | 82 | 426 | 80.8 (344 / 426) (76.7, 84.2) | - | 2.25 (1.88, 2.69) |
| | Gray Zone | 58 | 45 | 103 | 56.3 (58 / 103) (46.7, 65.5) | 43.7 (45 / 103) (34.5, 53.3) | 0.69 (0.48, 0.99) |
| | Negative | 11 | 402 | 413 | - | 80.3 (102 / 127) (72.6, 86.3) | 0.13 (0.09, 0.20) |
| | Total | 427 | 229 | 656 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 69.31% (131/189) | Positive | 107 | 22 | 129 | 82.9 (107 / 129) (75.5, 88.5) | - | 2.15 (1.53, 3.02) |
| | Gray Zone | 24 | 21 | 45 | 53.3 (24 / 45) (39.1, 67.1) | 46.7 (21 / 45) (32.9, 60.9) | 0.51 (0.31, 0.83) |
| | Negative | 2 | 36 | 38 | - | 100.0 (15 / 15) (79.6, 100.0) | 0.01 (0.00, 0.24) |
| | Total | 131 | 58 | 189 | | | |
| All Subjects with History of HF Pretest Probability of | Positive | 554 | 121 | 675 | 82.1 (554 / 675) (79.0, 84.8) | - | 2.26 (1.95, 2.62) |
| | Gray Zone | 87 | 69 | 156 | 55.8 (87 / 156) (47.9, 63.3) | 44.2 (69 / 156) (36.7, 52.1) | 0.62 (0.47, 0.83) |
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| HF (Prevalence of HF in study): 66.93% (672/1004) | Negative | 31 | 142 | 173 | - | 82.1 (142 / 173) (75.8, 87.1) | 0.11 (0.07, 0.16) |
| | Total | 672 | 332 | 1004 | | | |
Clinical Performance – Subjects without a History of Heart Failure:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 15.28% (46/301) | Positive | 37 | 31 | 68 | 54.4 (37 / 68) (42.7, 65.7) | - | 6.62 (4.62, 9.48) |
| | Gray Zone | 2 | 10 | 12 | 16.7 (2 / 12) (4.7, 44.8) | 83.3 (10 / 12) (55.2, 95.3) | 1.11 (0.25, 4.90) |
| | Negative | 7 | 214 | 221 | - | 96.8 (214 / 221) (93.6, 98.5) | 0.18 (0.09, 0.36) |
| | Total | 46 | 255 | 301 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 18.10% (126/696) | Positive | 93 | 66 | 159 | 58.5 (93 / 159) (50.7, 65.9) | - | 6.37 (4.97, 8.18) |
| | Gray Zone | 22 | 102 | 124 | 17.7 (22 / 124) (12.0, 25.4) | 82.3 (102 / 124) (74.6, 88.0) | 0.98 (0.64, 1.48) |
| | Negative | 11 | 402 | 413 | - | 97.3 (402 / 413) (95.3, 98.5) | 0.12 (0.07, 0.22) |
| | Total | 126 | 570 | 696 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 28.57% (36/126) | Positive | 24 | 16 | 40 | 60.0 (24 / 40) (44.6, 73.7) | - | 3.75 (2.27, 6.19) |
| | Gray Zone | 10 | 38 | 48 | 20.8 (10 / 48) (11.7, 34.3) | 79.2 (38 / 48) (65.7, 88.3) | 0.66 (0.37, 1.17) |
| | Negative | 2 | 36 | 38 | - | 94.7 (36 / 38) (82.7, 98.5) | 0.14 (0.04, 0.55) |
| | Total | 36 | 90 | 126 | | | |
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| All Subjects without History of HF Pretest Probability of HF (Prevalence of HF in study): 18.52% (208/1123) | Positive | 154 | 113 | 267 | 57.7 (154 / 267) (51.7, 63.5) | - | 6.00 (4.96, 7.25) |
| | Gray Zone | 34 | 150 | 184 | 18.5 (34 / 184) (13.5, 24.7) | 81.5 (150 / 184) (75.3, 86.5) | 1.00 (0.71, 1.40) |
| | Negative | 20 | 652 | 672 | - | 97.0 (652 / 672) (95.4, 98.1) | 0.13 (0.09, 0.21) |
| | Total | 208 | 915 | 1123 | | | |
Clinical Performance – Subjects with eGFR < 60 mL/min/1.73 m²:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 72.22% (39/54) | Positive | 37 | 5 | 42 | 88.1 (37 / 42) (75.0, 94.8) | - | 2.85 (1.39, 5.84) |
| | Gray Zone | 1 | 0 | 1 | 100.0 (1 / 1) (20.7, 100.0) | 0.0 (0 / 1) (0.0, 79.3) | 1.18 (0.05, 27.37) |
| | Negative | 1 | 10 | 11 | - | 90.9 (10 / 11) (62.3, 98.4) | 0.04 (0.01, 0.28) |
| | Total | 39 | 15 | 54 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 57.11% (237/415) | Positive | 201 | 58 | 259 | 77.6 (201 / 259) (72.1, 82.3) | - | 2.60 (2.09, 3.24) |
| | Gray Zone | 27 | 50 | 77 | 35.1 (27 / 77) (25.3, 46.2) | 64.9 (50 / 77) (53.8, 74.7) | 0.41 (0.26, 0.62) |
| | Negative | 9 | 70 | 79 | - | 88.6 (70 / 79) (79.7, 93.9) | 0.10 (0.05, 0.19) |
| | Total | 237 | 178 | 415 | | | |
| Age Group (years): >75 Pretest Probability of | Positive | 78 | 22 | 100 | 78.0 (78 / 100) (68.9, 85.0) | - | 2.45 (1.72, 3.49) |
| | Gray Zone | 16 | 22 | 38 | 42.1 (16 / 38) | 57.9 (22 / 38) | 0.50 (0.29, 0.88) |
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| HF (Prevalence of HF in study): 59.12% (94/159) | | | | | (27.9, 57.8) | (42.2, 72.1) | |
| | Negative | 0 | 21 | 21 | - | 100.0 (21 / 21) (84.5, 100.0) | 0.02 (0.00, 0.26) |
| | Total | 94 | 65 | 159 | | | |
| Subjects with eGFR<60 mL/min/1.73m² Pretest Probability of HF (Prevalence of HF in study): 58.92% (370/628) | Positive | 316 | 85 | 401 | 78.8 (316 / 401) (74.5, 82.5) | - | 2.59 (2.17, 3.10) |
| | Gray Zone | 44 | 72 | 116 | 37.9 (44 / 116) (29.6, 47.0) | 62.1 (72 / 116) (53.0, 70.4) | 0.43 (0.30, 0.60) |
| | Negative | 10 | 101 | 111 | - | 91.0 (101 / 111) (84.2, 95.0) | 0.07 (0.04, 0.13) |
| | Total | 370 | 258 | 628 | | | |
Clinical Performance – Subjects with eGFR ≥ 60 mL/min/1.73 m²:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 30.25% (121/400) | Positive | 103 | 43 | 146 | 70.5 (103 / 146) (62.7, 77.3) | - | 5.52 (4.15, 7.34) |
| | Gray Zone | 6 | 13 | 19 | 31.6 (6 / 19) (15.4, 54.0) | 68.4 (13 / 19) (46.0, 84.6) | 1.06 (0.41, 2.73) |
| | Negative | 12 | 223 | 235 | - | 94.9 (223 / 235) (91.3, 97.1) | 0.12 (0.07, 0.21) |
| | Total | 121 | 279 | 400 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 33.51% (312/931) | Positive | 232 | 90 | 322 | 72.0 (232 / 322) (66.9, 76.7) | - | 5.11 (4.18, 6.26) |
| | Gray Zone | 53 | 97 | 150 | 35.3 (53 / 150) (28.1, 43.3) | 64.7 (97 / 150) (56.7, 71.9) | 1.08 (0.80, 1.47) |
| | Negative | 27 | 432 | 459 | - | 94.1 (432 / 459) (91.6, 95.9) | 0.12 (0.09, 0.18) |
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| | Total | 312 | 619 | 931 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 46.45% (72/155) | Positive | 52 | 16 | 68 | 76.5 (52 / 68) (65.1, 85.0) | - | 3.75 (2.36, 5.95) |
| | Gray Zone | 18 | 37 | 55 | 32.7 (18 / 55) (21.8, 45.9) | 67.3 (37 / 55) (54.1, 78.2) | 0.56 (0.35, 0.89) |
| | Negative | 2 | 30 | 32 | - | 93.8 (30 / 32) (79.9, 98.3) | 0.08 (0.02, 0.31) |
| | Total | 72 | 83 | 155 | | | |
| All Subjects with eGFR≥60 mL/min/1.73m² Pretest Probability of HF (Prevalence of HF in study): 33.98% (505/1486) | Positive | 387 | 149 | 536 | 72.2 (387 / 536) (68.3, 75.8) | - | 5.05 (4.32, 5.89) |
| | Gray Zone | 77 | 147 | 224 | 34.4 (77 / 224) (28.5, 40.8) | 65.6 (147 / 224) (59.2, 71.5) | 1.02 (0.79, 1.31) |
| | Negative | 41 | 685 | 726 | - | 94.4 (685 / 726) (92.4, 95.8) | 0.12 (0.09, 0.16) |
| | Total | 505 | 981 | 1486 | | | |
Clinical Performance – Subjects with BMI $\geq 30\mathrm{kg} / \mathrm{m}^2$ :
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 40.75% (108/265) | Positive | 90 | 26 | 116 | 77.6 (90 / 116) (69.2, 84.2) | - | 5.03 (3.51, 7.22) |
| | Gray Zone | 7 | 8 | 15 | 46.7 (7 / 15) (24.8, 69.9) | 53.3 (8 / 15) (30.1, 75.2) | 1.27 (0.48, 3.40) |
| | Negative | 11 | 123 | 134 | - | 91.8 (123 / 134) (85.9, 95.4) | 0.13 (0.07, 0.23) |
| | Total | 108 | 157 | 265 | | | |
| Age Group (years): 50 - 75 | Positive | 231 | 54 | 285 | 81.1 (231 / 285) (76.1, 85.2) | - | 4.84 (3.74, 6.25) |
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Pretest Probability of HF (Prevalence of HF in study): 46.92% (328/699) | Gray Zone | 67 | 64 | 131 | 51.1 (67 / 131) (42.7, 59.5) | 48.9 (64 / 131) (40.5, 57.3) | 1.18 (0.87, 1.61) |
| | Negative | 30 | 253 | 283 | - | 89.4 (253 / 283) (85.3, 92.5) | 0.13 (0.09, 0.19) |
| | Total | 328 | 371 | 699 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 59.81% (64/107) | Positive | 48 | 5 | 53 | 90.6 (48 / 53) (79.7, 95.9) | - | 6.45 (2.80, 14.88) |
| | Gray Zone | 16 | 19 | 35 | 45.7 (16 / 35) (30.5, 61.8) | 54.3 (19 / 35) (38.2, 69.5) | 0.57 (0.33, 0.97) |
| | Negative | 0 | 19 | 19 | - | 100.0 (19 / 19) (83.2, 100.0) | 0.02 (0.00, 0.28) |
| | Total | 64 | 43 | 107 | | | |
| All Subjects with BMI ≥ 30 kg/m² Pretest Probability of HF (Prevalence of HF in study): 46.69% (500/1071) | Positive | 369 | 85 | 454 | 81.3 (369 / 454) (77.4, 84.6) | - | 4.96 (4.05, 6.07) |
| | Gray Zone | 90 | 91 | 181 | 49.7 (90 / 181) (42.5, 56.9) | 50.3 (91 / 181) (43.1, 57.5) | 1.13 (0.87, 1.47) |
| | Negative | 41 | 395 | 436 | - | 90.6 (395 / 436) (87.5, 93.0) | 0.12 (0.09, 0.16) |
| | Total | 500 | 571 | 1071 | | | |
Clinical Performance – Subjects with BMI < 30 kg/m²:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 30.41% (45/148) | Positive | 44 | 16 | 60 | 73.3 (44 / 60) (61.0, 82.9) | - | 6.29 (4.00, 9.90) |
| | Gray Zone | 0 | 4 | 4 | 0.0 (0 / 4) (0.0, 49.0) | 100.0 (4 / 4) (51.0, 100.0) | 0.25 (0.01, 4.60) |
| | Negative | 1 | 83 | 84 | - | 98.8 (83 / 84) | 0.03 (0.00, 0.19) |
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| | | | | | | (93.6, 99.8) | |
| | Total | 45 | 103 | 148 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 36.46% (198/543) | Positive | 185 | 80 | 265 | 69.8 (185 / 265) (64.0, 75.0) | - | 4.03 (3.31, 4.90) |
| | Gray Zone | 9 | 69 | 78 | 11.5 (9 / 78) (6.2, 20.5) | 88.5 (69 / 78) (79.5, 93.8) | 0.23 (0.12, 0.45) |
| | Negative | 4 | 196 | 200 | - | 98.0 (196 / 200) (95.0, 99.2) | 0.04 (0.01, 0.09) |
| | Total | 198 | 345 | 543 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 51.08% (95/186) | Positive | 76 | 31 | 107 | 71.0 (76 / 107) (61.8, 78.8) | - | 2.35 (1.73, 3.18) |
| | Gray Zone | 17 | 32 | 49 | 34.7 (17 / 49) (22.9, 48.7) | 65.3 (32 / 49) (51.3, 77.1) | 0.51 (0.30, 0.85) |
| | Negative | 2 | 28 | 30 | - | 93.3 (28 / 30) (78.7, 98.2) | 0.07 (0.02, 0.28) |
| | Total | 95 | 91 | 186 | | | |
| All Subjects with BMI < 30 kg/m2 Pretest Probability of HF (Prevalence of HF in study): 38.54% (338/877) | Positive | 305 | 127 | 432 | 70.6 (305 / 432) (66.1, 74.7) | - | 3.83 (3.28, 4.48) |
| | Gray Zone | 26 | 105 | 131 | 19.8 (26 / 131) (13.9, 27.5) | 80.2 (105 / 131) (72.5, 86.1) | 0.39 (0.26, 0.59) |
| | Negative | 7 | 307 | 314 | - | 97.8 (307 / 314) (95.5, 98.9) | 0.04 (0.02, 0.08) |
| | Total | 338 | 539 | 877 | | | |
Clinical Performance - Subjects with Comorbidities:
Comorbidities include at least one of the following: diabetes, renal dysfunction (eGFR less than $60~\mathrm{mL / min} / 1.73~\mathrm{m2}$ ), hypertension, and/or chronic obstructive pulmonary disease (COPD). The sponsor described in the labeling that patients with these comorbidities had a higher rate of false positives compared to patients without these comorbidities.
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| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50
Pretest Probability of HF
(Prevalence of HF in study): 43.67%
(131/300) | Positive | 115 | 34 | 149 | 77.2
(115 / 149)
(69.8, 83.2) | - | 4.36
(3.21, 5.93) |
| | Gray Zone | 7 | 10 | 17 | 41.2
(7 / 17)
(21.6, 64.0) | 58.8
(10 / 17)
(36.0, 78.4) | 0.90
(0.35, 2.31) |
| | Negative | 9 | 125 | 134 | - | 93.3
(125 / 134)
(87.7, 96.4) | 0.09
(0.05, 0.18) |
| | Total | 131 | 169 | 300 | | | |
| Age Group (years): 50 - 75
Pretest Probability of HF
(Prevalence of HF in study): 43.23%
(527/1219) | Positive | 415 | 136 | 551 | 75.3
(415 / 551)
(71.6, 78.7) | - | 4.01
(3.42, 4.69) |
| | Gray Zone | 78 | 133 | 211 | 37.0
(78 / 211)
(30.7, 43.7) | 63.0
(133 / 211)
(56.3, 69.3) | 0.77
(0.60, 0.99) |
| | Negative | 34 | 423 | 457 | - | 92.6
(423 / 457)
(89.8, 94.6) | 0.11
(0.08, 0.15) |
| | Total | 527 | 692 | 1219 | | | |
| Age Group (years): >75
Pretest Probability of HF
(Prevalence of HF in study): 55.25%
(163/295) | Positive | 128 | 36 | 164 | 78.0
(128 / 164)
(71.1, 83.7) | - | 2.88
(2.15, 3.85) |
| | Gray Zone | 33 | 48 | 81 | 40.7
(33 / 81)
(30.7, 51.6) | 59.3
(48 / 81)
(48.4, 69.3) | 0.56
(0.38, 0.81) |
| | Negative | 2 | 48 | 50 | - | 96.0
(48 / 50)
(86.5, 98.9) | 0.03
(0.01, 0.14) |
| | Total | 163 | 132 | 295 | | | |
| Subjects with Comorbidities
Pretest Probability of HF
(Prevalence of HF in study): 45.26%
(821/1814) | Positive | 658 | 206 | 864 | 76.2
(658 / 864)
(73.2, 78.9) | - | 3.86
(3.41, 4.38) |
| | Gray Zone | 118 | 191 | 309 | 38.2
(118 / 309)
(32.9, 43.7) | 61.8
(191 / 309)
(56.3, 67.1) | 0.75
(0.61, 0.92) |
| | Negative | 45 | 596 | 641 | - | 93.0
(596 / 641)
(90.7, 94.7) | 0.09
(0.07, 0.12) |
| | Total | 821 | 993 | 1814 | | | |
{27}
Clinical Performance – Subjects without Comorbidities:
| Category | NT-proBNP Test Result | Adjudicated Diagnosis | | Total | Posttest Probability of HF % (n / N) (95% CI) | Posttest Probability of Non-HF % (n / N) (95% CI) | Likelihood Ratio (HF) (95% CI) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| | | HF | Non-HF | | | | |
| Age Group (years): 18 - <50 Pretest Probability of HF (Prevalence of HF in study): 18.13% (29/160) | Positive | 25 | 14 | 39 | 64.1 (25 / 39) (48.4, 77.3) | - | 8.07 (4.81, 13.51) |
| | Gray Zone | 0 | 3 | 3 | 0.0 (0 / 3) (0.0, 56.1) | 100.0 (3 / 3) (43.9, 100.0) | 0.64 (0.03, 12.00) |
| | Negative | 4 | 114 | 118 | - | 96.6 (114 / 118) (91.6, 98.7) | 0.16 (0.06, 0.39) |
| | Total | 29 | 131 | 160 | | | |
| Age Group (years): 50 - 75 Pretest Probability of HF (Prevalence of HF in study): 19.55% (26/133) | Positive | 22 | 12 | 34 | 64.7 (22 / 34) (47.9, 78.5) | - | 7.54 (4.32, 13.18) |
| | Gray Zone | 2 | 14 | 16 | 12.5 (2 / 16) (3.5, 36.0) | 87.5 (14 / 16) (64.0, 96.5) | 0.59 (0.14, 2.43) |
| | Negative | 2 | 81 | 83 | - | 97.6 (81 / 83) (91.6, 99.3) | 0.10 (0.03, 0.39) |
| | Total | 26 | 107 | 133 | | | |
| Age Group (years): >75 Pretest Probability of HF (Prevalence of HF in study): 20.00% (4/20) | Positive | 3 | 2 | 5 | 60.0 (3 / 5) (23.1, 88.2) | - | 6.00 (1.46, 24.69) |
| | Gray Zone | 1 | 11 | 12 | 8.3 (1 / 12) (1.5, 35.4) | 91.7 (11 / 12) (64.6, 98.5) | 0.36 (0.06, 2.05) |
| | Negative | 0 | 3 | 3 | - | 100.0 (3 / 3) (43.9, 100.0) | 0.52 (0.03, 8.39) |
| | Total | 4 | 16 | 20 | | | |
| Subjects without Comorbidities Pretest Probability of HF (Prevalence of HF in study): 18.85% (59/313) | Positive | 50 | 28 | 78 | 64.1 (50 / 78) (53.0, 73.9) | - | 7.69 (5.33, 11.08) |
| | Gray Zone | 3 | 28 | 31 | 9.7 (3 / 31) (3.3, 24.9) | 90.3 (28 / 31) (75.1, 96.7) | 0.46 (0.15, 1.47) |
| | Negative | 6 | 198 | 204 | - | 97.1 (198 / 204) (93.7, 98.6) | 0.13 (0.06, 0.28) |
| | Total | 59 | 254 | 313 | | | |
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The sponsor included the following statements in their instructions for use concerning the performance of their device in ED settings in certain clinical subgroups:
- Patients with a history of HF had a higher rate of false positives compared to patients without a history of HF. Of the 332 total patients with a history of HF and adjudicated as non-HF, 121 (36.4%) had NT-proBNP concentrations greater than or equal to age-dependent cutoffs. Of the 915 total patients with no history of HF and adjudicated as non-HF, 113 (12.3%) had NT-proBNP concentrations greater than or equal to age-dependent cutoffs. This difference is likely due to long-standing chronic elevation of NT-proBNP in patients with a previous diagnosis of HF. Results should always be assessed in conjunction with patient's medical history, clinical examination, and other findings.
- Patients with an eGFR less than 60 mL/min/1.73 m² had a higher rate of false positives compared to patients with an eGFR greater than or equal to 60 mL/min/1.73 m². Of the 258 total patients with an eGFR less than 60 mL/min/1.73 m² and adjudicated as non-HF, 85 (32.9%) had NT-proBNP concentrations greater than or equal to age-dependent cutoffs. Of the 981 total patients with an eGFR greater than or equal to 60 mL/min/1.73 m² and adjudicated as non-HF, 149 (15.2%) had NT-proBNP concentrations greater than or equal to age-dependent cutoffs. Eight patients adjudicated as non-HF (0.6%) had an unknown eGFR. Patients with an eGFR less than 60 mL/min/1.73 m² had a higher rate of false negatives (9.0% [10/111]) compared to patients with an eGFR greater than or equal to 60 mL/min/1.73 m² (5.6% [41/726]). All 10 of the false negatives in the eGFR less than 60 mL/min/1.73 m² group were from patients with a BMI greater than or equal to 30 kg/m². In patients with eGFR less than 60 mL/min/1.73 m², caution should be used when interpreting NT-proBNP results. Results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings.
- Patients with a BMI greater than or equal to 30 kg/m² had a higher rate of false negatives compared to patients with a BMI less than 30 kg/m². Of the total observed false negatives (51/880), 41 (80.4%) were from patients with a BMI greater than or equal to 30 kg/m², 7 (13.7%) were from patients with a BMI less than 30 kg/m², and 3 (5.9%) were from patients with an unknown BMI. In patients with a BMI less than 30 kg/m², the age greater than 75 years group had a higher rate of false negatives (6.7% [2/30]) than the other age groups. Results should always be assessed in conjunction with the patient's medical history, clinical examination, and other findings. In patients with obesity, natriuretic peptides should be interpreted with caution.
The sponsor also included the following limitation in their labeling:
- Elevated NT-proBNP concentrations may be associated with impaired renal function (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m²), history of HF and other conditions such as acute coronary syndrome, atrial fibrillation, pulmonary embolism, valvular heart disease, myocarditis, pulmonary hypertension, stroke, and sepsis, which may lead to false positive results. Obesity (body mass index [BMI] ≥ 30 kg/m²), and other conditions such as flash pulmonary edema, pericarditis, and cardiac
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tamponade may lower NT-proBNP concentrations, which may lead to false negative results.
# New York Heart Association (NYHA) Functional Classification
865 subjects had a NYHA functional classification. Descriptive statistics by the NYHA classification for the 865 subjects adjudicated to have HF for all subjects and for male and female subjects are presented in the table below:
| Statistics | NYHA Functional Classification | | |
| --- | --- | --- | --- |
| | Class II | Class III | Class IV |
| All Subjects | | | |
| N | 12 | 369 | 499 |
| Mean | 5535.8 | 5187.5 | 6485.6 |
| SD | 6834.18 | 7056.92 | 7829.43 |
| Min | 89.5 | 27.1 | 19.8 |
| 5thPercentile | 89.5 | 244.0 | 303.0 |
| 25thPercentile | 1319.5 | 989.4 | 1492.8 |
| Median | 2846.4 | 2817.5 | 3928.2 |
| 75thPercentile | 7399.7 | 6230.9 | 8349.3 |
| 95thPercentile | 23734.0 | 20653.1 | 22086.6 |
| Max | 23734.0 | 60716.9 | 59178.1 |
| Male Subjects | | | |
| N | 8 | 206 | 290 |
| Mean | 5469.9 | 5955.9 | 6475.2 |
| SD | 7566.03 | 7674.86 | 7547.84 |
| Min | 89.5 | 166.7 | 19.8 |
| 5thPercentile | 89.5 | 365.8 | 375.5 |
| 25thPercentile | 1954.8 | 1221.8 | 1599.4 |
| Median | 2846.4 | 3702.6 | 4094.2 |
| 75thPercentile | 5415.8 | 7202.5 | 8515.5 |
| 95thPercentile | 23734.0 | 21410.7 | 21598.1 |
| Max | 23734.0 | 60716.9 | 59178.1 |
| Female Subjects | | | |
| N | 4 | 163 | 209 |
| Mean | 5667.6 | 4216.4 | 6500.1 |
| SD | 6135.91 | 6073.57 | 8222.56 |
| Min | 264.5 | 27.1 | 22.8 |
| 5thPercentile | 264.5 | 149.2 | 159.4 |
| 25thPercentile | 492.6 | 749.2 | 1266.5 |
| Median | 4542.9 | 2172.1 | 3713.5 |
| 75thPercentile | 11967.5 | 5022.1 | 8159.8 |
| 95thPercentile | 13320.3 | 19295.7 | 24566.4 |
| Max | 13320.3 | 38880.9 | 47385.1 |
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# D Clinical Cut-Off:
The sponsor describes the following cut-offs for patients presenting to ED settings where new onset or exacerbation of HF is suspected:
| Age Group (Years) | NT-proBNP (pg/mL) | Interpretation |
| --- | --- | --- |
| All | <300.0 | Negative: HF unlikely |
| 18 to < 50 | ≥300.0 to < 450.0 | Grayzone: Indeterminate Consider other causes of NT-proBNP elevation. |
| 50 to 75 | ≥300.0 to < 900.0 | |
| >75 | ≥300.0 to < 1800.0 | |
| 18 to < 50 | ≥450.0 | Positive: HF likely |
| 50 to 75 | ≥900.0 | |
| >75 | ≥1800.0 | |
# E Expected Values/Reference Range:
A reference interval study was performed based on guidance from CLSI EP28-A3c.
$\mathrm{K}_2\mathrm{EDTA}$ plasma specimens were obtained from a total of 861 apparently healthy individuals ( $\geq$ 18 years old, 442 females and 419 males) from 3 external clinical sites located in the US. The age-range distribution and sex of the individuals are described in the table below:
The exclusion criteria used to exclude subjects were:
current smoker
- known cardiac condition and/or cardiac disease
high blood pressure (hypertension)
- kidney disease (eGFR $< 60 \mathrm{~mL} / \mathrm{min} / 1.73 \mathrm{~m}^{2}$ )
- diabetes (HbA1c $\geq 6.5\%$ )
- active cancer or diagnosis of cancer within the last five years
previous stroke
- lung disease within the last five years
thyroid disease
- recently reported high cholesterol or triglycerides
- reported abnormal troponin (>99th percentile or cutoff for normal)
- female known to be pregnant
previous enrollment in this study
The specimens were tested with the Alere NT-proBNP for Alinity i assay on the Alinity i system. Based on the results, the $95\%$ reference interval of an apparently healthy population for each sex and age range was determined to be as follows:
| Age Range | Sex | n | Median (pg/mL) | Reference Interval (2.5th to 97.5th Percentile) (pg/mL) |
| --- | --- | --- | --- | --- |
| 18 to < 50 years old | Female | 181 | 30.7 | < 15.8 to 104.8 |
| | Male | 137 | <15.8 | < 15.8 to 180.3 |
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| Age Range | Sex | n | Median (pg/mL) | Reference Interval (2.5th to 97.5th Percentile) (pg/mL) |
| --- | --- | --- | --- | --- |
| 50 to 75 years old | Female | 134 | 51.7 | < 15.8 to 334.1 |
| | Male | 146 | 39.9 | < 15.8 to 451.6 |
| > 75 years old | Female | 127 | 81.4 | < 15.8 to 956.1 |
| | Male | 136 | 65.1 | < 15.8 to 683.0 |
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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