STATUSFIRST CHF (CONGESTIVE HEART FAILURE) NT-PROBNP, MODEL 20204

K051596 · Nanogen, Inc. · NBC · Mar 13, 2006 · Clinical Chemistry

Device Facts

• Record ID: K051596
• Device Name: STATUSFIRST CHF (CONGESTIVE HEART FAILURE) NT-PROBNP, MODEL 20204
• Applicant: Nanogen, Inc.
• Product Code: NBC · Clinical Chemistry
• Decision Date: Mar 13, 2006
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 862.1117
• Device Class: Class 2

Indications for Use

StatusFirst™ CHF (Congestive Heart Failure) NT-proBNP is a rapid test for the in-vitro quantitative determination of N-terminal pro-Brain Natriuretic peptide (NT-proBNP) in human EDTA plasma. The device is intended for use with the DXpress™ Reader to provide quantitative results as an aid in the diagnosis of CHF.

Device Story

StatusFirst™ CHF is a rapid, quantitative chromatographic immunoassay for NT-proBNP in human EDTA plasma. The test device contains dye-conjugated polyclonal anti-NT-proBNP antibodies, biotin-conjugated monoclonal anti-NT-proBNP antibody, and streptavidin immobilized at the test band. The user dispenses a sample into the test device and inserts it into the DXpress™ Reader. The reader measures the intensity of the test band 15 minutes after sample addition and converts it to a concentration value using lot-specific calibration factors. The device is intended for clinical use as an aid in diagnosing CHF. Results are compared against age-stratified thresholds (125 pg/mL for <75 years; 450 pg/mL for ≥75 years) to assist healthcare providers in clinical decision-making. The device provides a rapid diagnostic aid, potentially facilitating faster clinical assessment of patients presenting with suspected heart failure.

Clinical Evidence

Method comparison study involving 688 subjects (355 CHF, 333 non-CHF). Samples measured using StatusFirst™ CHF NT-proBNP and Roche Elecsys® proBNP. Passing-Bablok regression analysis showed strong correlation across all subjects (slope 0.956, intercept 9.4 pg/mL, Spearman Rank correlation 0.973). Precision testing reported within-run CVs ranging from 11.1% to 16.8% and total CVs from 12.4% to 18.1% across the measuring range (20-5,000 pg/mL).

Technological Characteristics

Chromatographic immunoassay using biotin-streptavidin technology. Materials include dye-conjugated polyclonal and biotin-conjugated monoclonal anti-NT-proBNP antibodies. Form factor is a single-use test device used with the DXpress™ Reader. Calibration is provided via a lot-specific Data Chip. Performance validated per CLSI guidelines EP5-A, EP6-A, EP7-A, and EP17-A.

Indications for Use

Indicated for the in-vitro quantitative determination of NT-proBNP in human EDTA plasma as an aid in the diagnosis of Congestive Heart Failure (CHF).

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's Elecsys® pro-BNP Immunoassay (K032646)

Submission Summary (Full Text)

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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
ASSAY ONLY TEMPLATE

A. 510(k) Number:
k051596

B. Purpose for Submission:
New device

C. Measurand:
B-type Natriuretic Peptide

D. Type of Test:
Quantitative

E. Applicant:
Nanogen, Inc.

F. Proprietary and Established Names:
StatusFirst™ CHF NT-proBNP

G. Regulatory Information:
1. Regulation section:
21 CFR 862.1117
2. Classification:
Class II
3. Product code:
NBC
4. Panel:
75, Chemistry

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H. Intended Use:

1. Intended use(s):
See Indications for Use

2. Indication(s) for use:
StatusFirst™ CHF (Congestive Heart Failure) NT-proBNP is a rapid test for the in-vitro quantitative determination of N-terminal pro-Brain Natriuretic peptide (NT-proBNP) in human EDTA plasma. The device is intended for use with the DXpress™ Reader to provide quantitative results as an aid in the diagnosis of CHF.

3. Special conditions for use statement(s):
Prescription Use

4. Special instrument requirements:
Princeton BioMeditech DXpress™ Reader – cleared in k050955

I. Device Description:

Each box contains the following:

- 20 StatusFirst™ CHF test devices, each individually sealed in a foil pouch with a dessicant. Each test device contains dye conjugated polyclonal anti-NT-proBNP antibodies, biotin conjugated monoclonal anti-NT-proBNP antibody and streptavidin immobilized at the test band.
- 20 single use droppers
- 1 lot specific Data Chip with calibration information
- 1 package insert

J. Substantial Equivalence Information:

1. Predicate device name(s):
Roche Elecsys proBNP Immunoassay

2. Predicate 510(k) number(s):
k032646

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3. Comparison with predicate:

| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Expected values (cutoff) | 125 pg/mL for patients younger than 75 years and 450 pg/mL for patients 75 years and older | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Principle | Chromatographic immunoassay | Electrochemiluminescence immunoassay |
| Sample type | EDTA plasma only | Serum and plasma |
| Instrument | DXpress Reader | Elecsys instruments |
| Measuring range | 20-5000 pg/mL | 5-35,000 pg/mL |

K. Standard/Guidance Document Referenced (if applicable):

CLSI EP17-A, CLSI EP7-A, CLSI EP5-A, CLSI EP6-A

L. Test Principle:

The StatusFirst™ CHF test device utilizes biotin coupled anti-NT-proBNP antibody/streptavidin solid-phase chromatographic immunoassay technology to quantitatively determine the concentration of NT-proBNP in human EDTA plasma specimens. After a sample has been dispensed into the sample well, the StatusFirst™ CHF test device is placed in the DXpress™ Reader. The DXpress™ Reader displays the NT-proBNP concentration 15 minutes after sample addition. The DXpress™ Reader is programmed to convert the intensity of the test band (as indicated by the "pBNP" line on the test device) into a concentration of NT-proBNP automatically by using lot specific calibration factors supplied with each box of test devices. The NT-proBNP concentration in the sample correlates with the intensity of the test band.

M. Performance Characteristics (if/when applicable):

1. Analytical performance:

a. Precision/Reproducibility:

The precision of StatusFirst™ CHF test device was determined using samples where recombinant NT-proBNP was added at four concentrations. The within

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day and total precision was performed in two runs per day, in five replicates per run at each concentration level, for 15 days with three DXpress™ readers. The within-run, total variances and coefficients of variation (CVs) were computed according to CLSI guideline EP5-A. The results are shown below.

| Mean level (pg/mL) | Within-run | | Total | |
| --- | --- | --- | --- | --- |
| | SD (pg/mL) | CV (%) | SD (pg/mL) | CV (%) |
| 64.9 | 7.19 | 11.1 | 8.06 | 12.4 |
| 103.5 | 13.27 | 12.8 | 14.14 | 13.7 |
| 375.5 | 49.18 | 13.1 | 52.18 | 13.9 |
| 2145.8 | 361.4 | 16.8 | 388.0 | 18.1 |

# b. Linearity/assay reportable range:

Each plasma sample having an elevated NT-proBNP concentration (hi pool) was diluted with a sample pool with a low NT-proBNP concentration (&lt;20 pg/mL) for a total of nine values spanning the measuring range of the StatusFirst™ CHF test device. Each undiluted and diluted sample was tested in 15 replicates. The results are shown in the table below.

| % of high pool | Expected pg/mL | Observed pg/mL | % Recovery |
| --- | --- | --- | --- |
| 0 | N/A | 19.46 | N/A |
| 0.45 | 42.6 | 38.9 | 91.3 |
| 1.25 | 83.8 | 74.1 | 88.4 |
| 2.8 | 163.6 | 139.2 | 85.1 |
| 7.4 | 400.3 | 399.9 | 99.9 |
| 15.1 | 796.6 | 791.9 | 99.4 |
| 30.55 | 1591.7 | 1548.3 | 97.3 |
| 46 | 2386.9 | 2574.9 | 107.9 |
| 61.4 | 3179.4 | 3269.7 | 102.8 |
| 76.85 | 3974.6 | 4141.5 | 104.2 |
| 100 | N/A | 5166 | N/A |

Intercept $= 16.0\mathrm{ng / mL}$ when plotting observed pg/mL versus $\%$ of high pool. The StatusFirst™ CHF test has been demonstrated to be linear from $20~\mathrm{pg / mL}$ to $5000~\mathrm{pg / mL}$ , within a $10\%$ deviation from linearity in this interval, calculated in accordance with CLSI Protocol EP6-A, "Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach."

c. Traceability, Stability, Expected values (controls, calibrators, or methods): Traceable to Roche Elecsys proBNP assay

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# d. Detection limit:

The limit of detection, (LoD), represents the lowest known concentration of NT-proBNP that can be reliably differentiated from zero. The LoD of the StatusFirst™ CHF test is $20~\mathrm{pg / mL}$ , determined according to Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) guideline EP17-A and with proportions of false positives $(\alpha)$ less than $5\%$ and false negatives $(\beta)$ less than $5\%$ based on 120 determinations, with 60 blank and 60 low-level samples (limit of blank $= 5\mathrm{pg / mL}$ ).

# e. Analytical specificity:

The following proteins and peptides were tested for potential cross-reactivity in the StatusFirst™ CHF test device at the maximum concentration of substance indicated. No substance demonstrated significant cross-reactivity (all cross-reactivities $&lt; 0.1\%$ ) when added to sample containing a recombinant NT-proBNP concentration of approximately $200~\mathrm{pg / mL}$ . The results are shown in the table below.

| Substance | Maximum Concentration | Cross-reactivity (%) |
| --- | --- | --- |
| BNP-32 | 1 μg/mL | 0.0018 |
| cTnI | 3 μg/mL | < 0.001 |
| cTnI/T/C complex | 1 μg/mL | < 0.001 |
| CK-MB | 3 μg/mL | < 0.001 |
| α-Atrial Natriuretic Polypeptide(α-ANP)(1-28) | 1 μg/mL | < 0.001 |
| Prepro-ANP(26-55), ProANP(1-30) Human | 1 μg/mL | 0.0012 |
| Prepro-ANP(56-92) Human | 1 μg/mL | 0.0012 |
| Prepro-ANP(104-123), Human | 1 μg/mL | 0.0016 |
| CNP(C-type natriuretic peptide) | 1 μg/mL | 0.0022 |
| Urodilatin | 0.1 μg/mL | 0.0080 |
| Angiotensin I | 0.1 μg/mL | 0.0192 |
| Angiotensin II | 0.1 μg/mL | 0.0212 |
| Angiotensin III | 0.1 μg/mL | 0.0033 |
| Endothelin I | 0.1 μg/mL | 0.0154 |
| Adrenomedullin (AMD) | 0.1 μg/mL | 0.0070 |
| Arg-Vasopressin | 0.1 μg/mL | <0.001 |
| Renin | 0.05 μg/mL | 0.0210 |
| Aldosterone | 1 μg/mL | 0.0013 |

Sixty-three drugs were assessed for potential interference in the StatusFirst™ CHF test device. The list of drugs encompassed common prescription and

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over-the-counter compounds, as well as medications often prescribed in a CHF patient population. The drugs were tested at concentrations as recommended in the CLSI Approved Guideline EP7-A 'Interference Testing in Clinical Chemistry', or at least three times the highest concentration reported following a therapeutic dosage. No significant interference with the StatusFirst™ CHF measurement was observed for the drugs listed in the table below.

| Drug | Drug | Drug |
| --- | --- | --- |
| Abciximab | Digoxin | Nitrofurantoin |
| Acetaminophen | Diltiazem | Nitroglycerin |
| Acetylsalicylic acid | Dipyridamole | Noramidopyren |
| Allopurinol | Dopamine | Nystatin |
| Alteplase | Enalapril maleate | Oxazepam |
| Ambroxol | Eptafibitide | Oxytetracycline |
| Amiodarone | Erythromycin | Phenobarbital |
| Amlodipine Besylate | Fluvastatin | Phenytoin |
| Ampicillin | Furosemide | Pravastatin |
| Ascorbic acid (vitamin C) | Glyburide | Probenecid |
| Atenolol | Heparin | Procainamide |
| Atorvastatin | Hydralazine | Propranolol |
| Caffeine | Hydrochlorothiazide | Quinidine |
| Captopril | Indomethacin | Simvastatin |
| Chloramphenicol | Isosorbide dinitrate | Spironolactone |
| Chlordiazepoxide | Lisinopril | Sulfamethoxazole |
| Cinnarizine | Methaqualone | Theophylline |
| Clopidogrel bisulphate | Methyl-DOPA | L-thyroxine |
| Cyclosporine A | Milrinone lactate | Trimethoprim |
| Diclofenac | Nicotine | Verapamil |
| Digitoxin | Nifedipine | Warfarin |

Other Interfering Substances:

When added to a sample containing NT-proBNP, hemoglobin (up to 0.1 g/dL), bilirubin (up to 10 mg/dL), triglycerides (up to 1.5 g/dL), creatinine (up to 20 µg/mL), and d-biotin (up to 0.1 µg/mL) did not interfere with the recovery of NT-proBNP. No interference was observed from rheumatoid factors (up to 2030 IU/mL) or from high levels of human albumin (up to 16 g/dL).

f. Assay cut-off:

The sponsor recommends decision threshold values as follows: Patients under 75 years of age: 125 pg/mL

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Patients 75 years of age and older: $450~\mathrm{pg / mL}$

NT-proBNP results less than or equal to the decision threshold values are considered normal values representative of patients without CHF

Results greater than the above stated decision threshold values are considered abnormal and suggestive of patients with CHF.

# 2. Comparison studies:

a. Method comparison with predicate device:

A substantial equivalence study was performed between the StatusFirst™ CHF and the Roche Elecsys® 2010 proBNP assays using clinical samples within the measuring range of both assays (n=648). When plotting the StatusFirst™ results versus the Roche Elecsys® results, the data showed a slope of 0.956 and intercept of $9.4~\mathrm{pg / mL}$ (Passing Bablok regression), and a Spearman Rank correlation of 0.973.

b. Matrix comparison:

EDTA plasma is the only sample type indicated

# 3. Clinical studies:

a. Clinical Sensitivity:

Cut off levels of $125~\mathrm{pg / mL}$ for subjects under 75 years of age and $450~\mathrm{pg / mL}$ for subjects over 75 years of age were used to calculate the sensitivity (for CHF subjects) and specificity (for non-CHF subjects) values of the StatusFirst™ CHF assay. The results are shown in the table below.

| Subjects < 75 years old | | | Total |
| --- | --- | --- | --- |
| StatusFirst™ CHF | CHF | Non-CHF | |
| < 125 pg/mL | 17 | 131 | 148 |
| ≥ 125 pg/mL | 199 | 55 | 254 |
| Total | 216 | 186 | 402 |
| Subjects ≥ 75 years old | | | |
| StatusFirst™ CHF | CHF | Non-CHF | |
| < 450 pg/mL | 17 | 83 | 100 |
| ≥ 450 pg/mL | 122 | 13 | 135 |
| Total | 139 | 96 | 235 |

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The estimates of sensitivities were as follows:

For the subjects less than 75 years of age:

92.1% (199/216)

For the subjects 75 years of age or older:

87.8% (122/139)

The estimates of specificities were as follows:

For the subjects less than 75 years of age:

70.4% (131/186)

For the subjects 75 years of age or older:

86.5% (83/96)

b. Clinical specificity:

See Clinical Sensitivity section above.

c. Other clinical supportive data (when a. and b. are not applicable):

Cut off levels of 125 pg/mL for subjects under 75 years of age and 450 pg/mL for subjects over 75 years of age were used to calculate the sensitivity (for CHF subjects) and specificity (for non-CHF subjects) values of the

StatusFirst™ CHF and the Elecsys® proBNP tests. The results are shown in the tables below:

216 CHF subjects &lt; 75 years of age

| | Elecsys | | | |
| --- | --- | --- | --- | --- |
| | | < 125 pg/mL | | ≥ 125 pg/mL |
| StatusFirst | < 125 pg/mL | 13 | 4 | 17 |
| | ≥ 125 pg/mL | 1 | 198 | 199 |
| | | 14 | 202 | 216 |

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39 CHF subjects 75+ years of age

| | Elecsys | | | |
| --- | --- | --- | --- | --- |
| | | < 450 pg/mL | | ≥ 450 pg/mL |
| StatusFirst | < 450 pg/mL | 17 | 0 | 17 |
| | ≥ 450 pg/mL | 5 | 117 | 122 |
| | | 22 | 117 | 139 |

The estimates of sensitivities were as follows:

For the subjects less than 75 years of age:

93.5% (202/216) for Roche Elecsys and 92.1% (199/216) for StatusFirst™;

For the subjects 75 years of age or older:

84.2% (117/139) for Roche Elecsys and 87.8% (122/139) for StatusFirst™.

186 non-CHF subjects &lt; 75 years of age

| | Elecsys | | | |
| --- | --- | --- | --- | --- |
| | | < 125 pg/mL | | ≥ 125 pg/mL |
| StatusFirst | < 125 pg/mL | 124 | 7 | 131 |
| | ≥ 125 pg/mL | 13 | 42 | 55 |
| | | 137 | 79 | 186 |

96 non-CHF subjects 75+ years of age

| | Elecsys | | | |
| --- | --- | --- | --- | --- |
| | | < 450 pg/mL | | ≥ 450 pg/mL |
| StatusFirst | < 450 pg/mL | 83 | 0 | 83 |
| | ≥ 450 pg/mL | 2 | 11 | 13 |
| | | 85 | 11 | 96 |

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The estimates of specificities were as follows:

For the subjects less than 75 years of age:

73.7% (137/186) for Roche Elecsys and 70.4% (131/186) for StatusFirst™;

For the subjects 75 years of age or older:

88.5% (85/96) for Roche Elecsys and 86.5% (83/96) for StatusFirst™.

Non-CHF subjects (diabetes, renal insufficiency, hypertension or chronic OPD)

12 subjects &lt; 75 years of age

| | Elecsys | | | |
| --- | --- | --- | --- | --- |
| | | < 125 pg/mL | | ≥ 125 pg/mL |
| StatusFirst | < 125 pg/mL | 7 | 0 | 7 |
| | ≥ 125 pg/mL | 0 | 5 | 5 |
| | | 7 | 5 | 12 |

39 subjects 75+ years of age

| | Elecsys | | | |
| --- | --- | --- | --- | --- |
| | | < 450 pg/mL | | ≥ 450 pg/mL |
| StatusFirst | < 450 pg/mL | 18 | 1 | 19 |
| | ≥ 450 pg/mL | 2 | 18 | 20 |
| | | 20 | 19 | 39 |

The estimates of specificities were as follows:

For the subjects less than 75 years of age:

58.3% (7/12) for Roche Elecsys and 58.3% (7/12) for StatusFirst™;

For the subjects 75 years of age or older:

51.3% (20/39) for Roche Elecsys and 48.7% (19/39) for StatusFirst™.

4. Clinical cut-off:

The diagnostic utility of the StatusFirst™ CHF test device in CHF patients versus those without CHF is demonstrated by the area under the Receiver Operator Characteristic (ROC) curve of 0.896, which indicates that the StatusFirst™ CHF

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is effective as an aid in the diagnosis of CHF.

StatusFirst™ ROC curves, stratified by age


Subjects less than 75 years old (216 CHF and 198 non-CHF)

Area under Curve (AUC) = 0.915

95% Confidence Interval= [0.884, 0.940]

Subjects 75 years or older (139 CHF and 135 non-CHF),

Area under curve $= 0.892$

95% Confidence Interval = [0.850, 0.926]

Boxplot of NT-proBNP levels for CHF and non-CHF cohorts


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5. Expected values/Reference range:

Individuals without CHF

From a population of 333 individuals without CHF (153 women, 180 men), the StatusFirst™ CHF test device was used to determine the concentration of NT-proBNP. This population included apparently healthy individuals and individuals with diabetes, renal insufficiency, hypertension or chronic obstructive pulmonary disease. Summary statistics for NT-proBNP in subjects are given below.

Non-CHF Subjects

| | Age Category (years) | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | < 45 | 45-54 | 55-64 | 65-74 | 75+ | < 75 |
| Median | 32.6 | 48.9 | 55.1 | 86.0 | 136.6 | 71.6 |
| 95^{th} percentile | (*) | 366.5 | 217.4 | 768.8 | 1850.5 | 593.0 |
| % < 125 pg/ml | 100 | 76.2 | 78.0 | 62.5 | - | 69.7 |
| % < 450 pg/ml | - | - | - | - | 75.6 | - |
| N | 6 | 21 | 59 | 112 | 135 | 198 |

(*) Insufficient sample size

Blood samples were obtained from 355 patients diagnosed with CHF (160 women and 195 men). Summary statistics for NT-proBNP concentrations in patients with CHF are presented in the tables below.

CHF Population

StatusFirst™ NT-proBNP levels (pg/mL) in males with CHF, stratified by NYHA Class

| | NYHA Functional Class | | | | |
| --- | --- | --- | --- | --- | --- |
| | All CHF | NYHA I | NYHA II | NYHA III | NYHA IV |
| Median | 1249.6 | 1052.0 | 1106.3 | 1351.0 | 2763.4 |
| 5^{th} percentile | 106.2 | 35.2 | 133.7 | 93.7 | 177.8 |
| 95^{th} percentile | >5000 | 3570.4 | >5000 | >5000 | >5000 |
| % > cutoff | 91.3 | 87.1 | 92.9 | 88.6 | 95.5 |
| Minimum | <20 | 29.0 | <20 | 59.7 | 117.1 |
| Maximum | >5000 | 3931.6 | >5000 | >5000 | >5000 |
| N | 195 | 31 | 98 | 44 | 22 |

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StatusFirst™ NT-proBNP levels (pg/mL) in females with CHF, stratified by NYHA Class

| | NYHA Functional Class | | | | |
| --- | --- | --- | --- | --- | --- |
| | All CHF | NYHA I | NYHA II | NYHA III | NYHA IV |
| Median | 1316.2 | 879.8 | 1588.9 | 1155.6 | 1052.1 |
| 5^{th} percentile | 109.7 | 73.6 | 131.7 | 142.5 | N/A |
| 95^{th} percentile | >5000 | 2700.2 | >5000 | >5000 | >5000 |
| % > cutoff | 89.4 | 90.5 | 89.8 | 86.7 | 90.9 |
| Minimum | 33.5 | 68.6 | 33.5 | 44.3 | 114.9 |
| Maximum | >5000 | 3268.5 | >5000 | >5000 | >5000 |
| N | 160 | 21 | 98 | 30 | 11 |

StatusFirst™ NT-proBNP levels (pg/mL) stratified by age group

| | Age Category (years) | | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | < 45 | 45-54 | 55-64 | 65-74 | 75+ | < 75 |
| Median | 1088.6 | 599.1 | 762.5 | 1265.8 | 1771.2 | 1015.6 |
| 95^{th} percentile | (*) | 1491.2 | 4096.0 | >5000 | >5000 | >5000 |
| % > 125 pg/ml | 87.5 | 80.0 | 89.4 | 95.9 | - | 92.1 |
| % > 450 pg/ml | - | - | - | - | 87.8 | - |
| N | 8 | 20 | 66 | 122 | 139 | 216 |

(*) Insufficient sample size

## N. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.

## O. Conclusion:

The submitted information in this premarket notification is complete and supports a substantial equivalence decision.