The Astute Medical NEPHROCHECK® Test System is intended to be used in conjunction with clinical evaluation in patients who currently have or have had within the past 24 hours acute cardiovascular and or respiratory compromise and are ICU patients as an aid in the risk assessment for moderate or severe acute kidney injury (AKI) within 12 hours of patient assessment. The NEPHROCHECK® Test System is intended to be used in patients 21 years of age or older.

Device Description

The NEPHROCHECK® Test System is comprised of the NEPHROCHECK® Test Kit, the ASTUTE140 Meter, the NEPHROCHECK® Liquid Controls Kit, and the NEPHROCHECK® Calibration Verification (Cal Vers) Materials Kit.

The NEPHROCHECK® Test Kit includes the NEPHROCHECK® Test which is a single-use cartridge comprised of two immunoassays for the protein biomarkers insulinlike growth factor-binding protein (IGFBP7) and tissue-inhibitor of metalloproteinases 2 (TIMP2), on a membrane test strip enclosed in a plastic housing. Internal positive and negative procedural controls in each NEPHROCHECK® Test cartridge monitor the function of each test cartridge. If the automatic check of these procedural controls shows that the control value results are not within pre-defined limits, the Meter will display an error message and the Test result will not be reported. The concentrations of the TIMP-2 and IGFBP-7 proteins are used to derive the AKIRisk Score and these concentrations are not reported.

Also included in the kit is test buffer and the NEPHROCHECK® Test Conjugate Vial which contains murine monoclonal and goat polyclonal antibodies against TIMP-2 and IGFBP-7, fluorescent dye, stabilizers and excipients. A RFID Card that contains lot and calibration information is included with each kit. The RFID card must be loaded prior to using a new kit. Each kit can perform 25 tests.

The ASTUTE140® Meter is a bench-top analyzer that converts the fluorescent signal from each of the two immunoassays contained within the NEPHROCHECK® Test cartridge into the AKIRisk score. Only the AKIRisk score appears on the meter display. The ASTUTE140® Meter contains an internal printer that can print the AKIRisk score

The NEPHROCHECK® Low Liquid Control and NEPHROCHECK® High Liquid Control are bi-level, lyophilized control materials prepared from human urine containing human TIMP-2 and human IGFBP-7 proteins with protein stabilizers. TIMP-2 and IGFBP-7 proteins have been added to the urine to achieve specified target concentration levels. The expected concentrations and standard deviations are printed on the enclosed RFID cards. Each NEPHROCHECK® Liquid Control Kit Vial is intended for single use only.

The NEPHROCHECK® Calibration Verification Kit includes five levels of lyophilized material prepared from human urine, containing TIMP-2 and human IGFBP-7 to achieve specified target concentration levels that evenly span the reportable ranges of the AKIRisk Score. The expected concentrations and standard deviations of the individual biomarkers are embedded on a RFID card enclosed with the NEPHROCHECK® Calibration Verification Kit.

All human source material used to manufacture NEPHROCHECK® Liquid Controls and the NEPHROCHECK® Calibration Verification Kit was non-reactive for antigens to Hepatitis B (HBsAg), negative by tests for antibodies to HIV (HIV-1/HIV-s) and Hepatitis C (HCV), non-reactive for HIV-1 RNA and HCV RNA by licensed NAT, and non-reactive to Serological Test for Syphilis (STS) using testing methods approved by the FDA.

AI/ML Overview

The NEPHROCHECK® Test System is intended to be used in conjunction with clinical evaluation as an aid in risk assessment for moderate or severe acute kidney injury (AKI) within 12 hours.

Here's an analysis of the acceptance criteria and the studies conducted:

1. Table of Acceptance Criteria and Reported Device Performance:

Performance Characteristic	Acceptance Criteria (Implicit)	Reported Device Performance (Study A, Combined Labs)	Reported Device Performance (Study B)
Clinical Sensitivity (TPR)	Sufficiently high to identify true AKI cases to aid in risk assessment.	0.90 - 0.93 (95% CI: 0.83-0.99)	0.76 (95% CI: 0.60-0.91)
Clinical Specificity (TNR)	Sufficient to differentiate non-AKI cases, acknowledging it's not a standalone diagnostic.	0.45 - 0.49 (95% CI: 0.39-0.54)	0.51 (95% CI: 0.41-0.60)
Negative Predictive Value (NPV)	High enough to confidently rule out AKI in low-risk patients.	0.96 - 0.97 (95% CI: 0.93-1.00)	0.88 (95% CI: 0.79-0.96)
Positive Predictive Value (PPV)	Provides useful information for risk assessment, even if relatively low, given the "aid in risk assessment" intended use.	0.26 - 0.27 (95% CI: 0.21-0.33)	0.31 (95% CI: 0.21-0.42)
Total Imprecision (%CV)	Within acceptable limits for a quantitative immunoassay (typically <15-20% for clinical analytes).	Ranged from 10.4% to 18.5% for S2-S7, and 8.6% to 12.1% for calibrators/controls, depending on the sample type and individual site/lot. All within acceptable range. Specifically, for samples around the cutoff (S3, S4, S5), %CVs ranged from 8.4% to 11.2%.	Not applicable (analytical performance).
Linearity/Reportable Range	Demonstrates appropriate linearity for the biomarker measurements and a defined reportable range for the AKIRisk Score.	Reportable range 0.04 - 10.0. Markers linear; AKIRisk Score not expected to be linear. No hook effect observed up to AKIRisk Score 250.	Not applicable (analytical performance).
Detection Limits (LoB, LoD, LoQ)	LoQ must be below the clinical cutoff.	LoB = 0.0002, LoD = 0.002, LoQ = 0.002. LoQ < clinical cutoff of 0.3.	Not applicable (analytical performance).
Interference	Minimal significant interference from common substances, drugs, and related biomarkers beyond specified limits.	Significant interference identified for Albumin (>1250 mg/L), Bilirubin (>72.1 mg/L), and Methylene blue (>0.49 mg/L). All other tested substances showed no significant interference.	Not applicable (analytical performance).
pH and Specific Gravity Effects	No significant effect on AKIRisk Score within recommended ranges.	No effect from pH (4, 6, 8, 10 tested) or specific gravity (1.001, 1.015±0.005, >1.0035 tested) within recommended ranges (pH 4.2-9.9, SG 0.998-1.038).	Not applicable (analytical performance).

2. Sample Sizes and Data Provenance for the Test Set:

Study A (Main Clinical Study):
- Enrollment: 519 patients.
- Evaluable Cohort (Test Set): 408 patients.
- Data Provenance: Multicenter, prospective study conducted at 23 geographically diverse sites in the US.
Study B (Confirmatory Clinical Study):
- Enrollment: 153 patients.
- Evaluable Cohort (Test Set): 126 patients.
- Data Provenance: Multicenter, prospective study conducted at 6 sites in the US.

The patients were ICU patients who currently have or had within the past 24 hours acute cardiovascular and/or respiratory compromise. Patients with known moderate or severe AKI (e.g., RIFLE I, F, or KDIGO stage 2 or 3) were excluded from enrollment.

3. Number of Experts and Qualifications for Ground Truth of the Test Set:

Number of Experts: An independent panel of expert nephrologists. The exact number is not explicitly stated, but "a panel" suggests more than one.
Qualifications: "Expert nephrologists." Specific experience years are not provided, but the term "expert" implies significant qualifications in the field of nephrology and AKI diagnosis.

4. Adjudication Method for the Test Set:

Method: Final diagnoses were adjudicated by an independent panel of expert nephrologists using practice standards to classify patients as "AKI" (moderate or severe AKI present) or "No AKI" within 12 hours of enrollment.
Blinding: Adjudicators were blinded to the site diagnoses and AKIRisk Score results.

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

No MRMC comparative effectiveness study was done as described in the provided text for human readers improving with or without AI assistance. This device is an in-vitro diagnostic test generating a numerical score, not an AI image analysis tool that assists human readers directly in interpreting complex data like medical images. The information provided focuses on the standalone performance of the test.

6. Standalone (Algorithm Only) Performance:

Yes, a standalone performance study was done. The entire clinical study (Study A and Study B) evaluated the performance of the NEPHROCHECK® Test System (an algorithm-derived score from biomarker measurements) in risk assessment for AKI. The reported sensitivity, specificity, PPV, and NPV are measures of this standalone algorithm's diagnostic performance against the adjudicated clinical outcome. The intended use explicitly states it is used "in conjunction with clinical evaluation," but the performance characteristics (sensitivity, specificity, etc.) are for the test result itself.

7. Type of Ground Truth Used:

The ground truth for the test set was established through expert consensus based on practice standards. The independent panel of expert nephrologists adjudicated patient outcomes as "AKI" (moderate or severe AKI present) or "No AKI" within 12 hours of enrollment based on accepted clinical practice standards. This is essentially a form of "clinical diagnosis" by experts.

8. Sample Size for the Training Set:

The document does not explicitly state a separate training set size for the AKIRisk Score algorithm development. It describes the analytical and clinical validation studies. The AKIRisk Score is derived from the measurement of IGFBP7 and TIMP2, and its algorithm would have been developed prior to these validation studies, likely using internal data or other published research. The document focuses on the validation of the device's performance, not its initial development.

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

Since a separate training set and its ground truth establishment are not explicitly detailed in the provided document, specific information on this is unavailable. However, for a device like this, the algorithm for combining TIMP-2 and IGFBP-7 into an AKIRisk score would typically be developed (trained) using a cohort of patients with known AKI outcomes, where AKI status is determined by clinical criteria (similar to the adjudication for the test set, or based on established diagnostic criteria like RIFLE/KDIGO). This development process usually precedes the formal clinical validation studies described.

Summary

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EVALUATION OF AUTOMATIC CLASS III DESIGNATION FOR NEPHROCHECK® Test System

DECISION SUMMARY

A. DEN Number:

DEN130031

B. Purpose for Submission:

De novo request for evaluation of automatic class III designation of the NEPHROCHECK® Test System.

C. Measurand:

The test reports an AKIRisk score derived from the measurement of Insulin-like growth factor-binding protein (IGFBP7) and tissue-inhibitor of metalloproteinases 2 (TIMP2).

D. Type of Test:

Quantitative immunoassay

E. Applicant:

Astute Medical, Inc.

F. Proprietary and Established Names:

NEPHROCHECK® Test System

G. Regulatory Information:

New Regulation section: 1.
21 CFR 862.1220
1. Classification:
  Class II
1. Product code:
  PIG
1. Panel:
  75, Clinical Chemistry

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H. Intended Use:

1. Intended use(s):
  The Astute Medical NEPHROCHECK® Test System is intended to be used in conjunction with clinical evaluation in patients who currently have or have had within the past 24 hours acute cardiovascular and or respiratory compromise and are ICU patients as an aid in the risk assessment for moderate or severe acute kidney injury (AKI) within 12 hours of patient assessment. The NEPHROCHECK® Test System is intended to be used in patients 21 years of age or older.
1. Indication(s) for use:
  Same as intended use.
1. Special conditions for use statement(s):
  Test results should be evaluated with other clinical and laboratory test information.

Test results are not to be used as a standalone test.

Test results should be used in patients 21 years of age and older.

For prescription use only.

This test system is for central laboratory use only. It is not for point-of-care use.

Subject to special controls under regulation 21 CFR 862.1220

1. Special instrument requirements:
  ASTUTE140® Meter

I. Device Description:

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J. Substantial Equivalence Information:

1. Predicate device name(s):
  Not applicable
1. Predicate 510(k) number(s):
  Not applicable
1. Comparison with predicate:
  Not applicable

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

CLSI EP 5A-2: Evaluation of Precision Performance of Quantitative Measurement Methods; Approved Guideline-Second Edition
CLSI EP 6A: Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; Approved Guideline
CLSI EP17-A: Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline
CLSI EP25-A: Evaluation of Stability of In Vitro diagnostic Reagents; Approved Guideline
CLSI C28-A3: Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline-Third Edition

L. Test Principle:

The NEPHROCHECK® Test is a sandwich fluorescent immunoassay. Test Buffer Solution and centrifuged urine supernatant are manually added by the operator to the Test Conjugate Vial containing the labeled fluorescent conjugate. A 100 uL aliquot of the urine/fluorescent conjugate mixture is dispensed into the sample port on the NEPHROCHECK® Test cartridge where it diffuses across a membrane containing the capture antibodies for TIMP-2 and IGFBP-7. After a brief waiting period, the NEPHROCHECK® Test Cartridge is inserted into the ASTUTE140® Meter for incubation, reading, result calculation and result display. The fluorescent signals from both biomarkers are incorporated into an algorithm to derive the AKIRisk Score. The NEPHROCHECK® Test result is displayed as a single value (AKIRisk score). The AKIRisk Score result is displayed on the Meter LCD screen in approximately 20 minutes from the addition of the specimen.

M. Performance Characteristics (if/when applicable):

1. Analytical performance:
- a. Precision/Reproducibility:

Precision of the NEPHROCHECK® Test AKIRisk Score was evaluated using a 20 day precision study conducted at 3 clinical laboratories (1 internal, 2 external sites) according to CLSI Guideline EP5-A2 using 6 urine samples which include samples around the AKIRisk Score cutoff (Samples S3, S4, and S5) and samples to span the range of the AKIRisk Score (Samples S2, S6 and S7). All samples were tested 2 times a day in replicates of 2 using 3 reagent lots (1 per site) for 20 days (N=80 per sample for each lot/site). Precision results are provided below for all sites/lots combined, as well as for each individual site/lot.

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All Sites/Lots

TestSpecimen	RiskScoreMean	Within-Run		Between Run		Between Day		Total Imprecision
		SD	%CV	SD	%CV	SD	%CV	SD	%CV
S2	0.04	0.006	15	0.0	0.0	0.004	9.8	0.007	18.3
S3	0.14	0.011	8.1	0.004	3.2	0.009	6.8	0.015	11.0
S4	0.30	0.027	9.0	0.006	1.8	0.001	4.9	0.031	10.4
S5	0.56	0.048	8.5	0.0	0.0	0.039	6.9	0.061	10.9
S6	4.61	0.335	7.3	0.205	4.5	0.141	3.1	0.418	9.1
S7	8.55	0.844	9.9	0.217	2.5	0.493	5.8	1.001	11.7

Site 1/Lot 1

Test	Risk	Within-Run		Between Run		Between Day		Total Imprecision
Specimen	ScoreMean	SD	%CV	SD	%CV	SD	%CV	SD	%CV
S2	0.04	0.008	18.3	0.0	0.0	0.001	2.1	0.008	18.5
S3	0.13	0.012	9.5	0.007	5.1	0.006	4.7	0.015	11.8
S4	0.31	0.030	9.8	0.013	4.5	0.009	3.1	0.034	11.2
S5	0.53	0.059	11.2	0.0	0.0	0.025	4.7	0.064	12.1
S6	4.60	0.448	9.7	0.172	3.7	0.0	0.0	0.480	10.4
S7	8.552	0.894	10.5	0.0	0.0	0.262	3.1	0.932	10.9

Site 2/Lot 2

Test	Risk	Within-Run		Between Run		Between Day		Total Imprecision
Specimen	ScoreMean	SD	%CV	SD	%CV	SD	%CV	SD	%CV
S2	0.04	0.005	11.8	0.0	0.0	0.003	6.4	0.005	13.4
83	0.15	0.011	7.4	0.004	2.4	0.005	3.7	0.013	8.6
S4	0.32	0.022	7.1	0.010	3.2	0.0	0.0	0.025	7.8
ડર	0.55	0.046	8.3	0.020	3.6	0.030	5.4	0.058	10.5
SQ	4.64	0.260	5.6	0.0	0.0	0.31	6.6	0.401	8.6
S7	8.10	0.544	6.7	0.147	1.8	0.502	6.2	0.754	9.3

Site 3/Lot 3

TestSpecimen	RiskScoreMean	Within-Run		Between Run		Between Day		Total Imprecision
		SD	%CV	SD	%CV	SD	%CV	SD	%CV
S2	0.04	0.005	12.7	0.0	0.0	0.001	3.5	0.005	13.2
S3	0.13	0.010	7.3	0.002	1.0	0.005	3.9	0.011	8.4
S4	0.29	0.029	10.0	0.0	0.0	0.009	3.2	0.030	10.5
S5	0.60	0.035	5.9	0.0	0.0	0.022	3.6	0.042	6.9
S6	4.58	0.263	5.7	0.313	6.8	0.0	0.0	0.408	8.9
S7	9.04	1.017	11.2	0.351	3.9	0.0	0.0	1.076	11.9

An additional in-house 20 day precision study was conducted according to CLSI Guideline EP5-A2 using the NEPHROCHECK® Calibration Verifiers (5 levels) and the NEPHROCHECK® Liquid Controls (2 levels). All samples were tested 2 times a day in replicates of 2 using 1 reagent lots for 20 days (N=80). Precision results are

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provided below.

TestSpecimen	RiskScoreMean	Within-Run		Between Run		Between Day		Total Imprecision
		SD	%CV	SD	%CV	SD	%CV	SD	%CV
Cal Ver 1	0.09	0.10	9.7	0.0	0.0	0.0	5.1	0.10	11.0
Cal Ver 2	0.28	0.03	9.5	0.0	0.0	0.01	3.6	0.03	10.2
Cal Ver 3	0.96	0.07	7.7	0.03	3.4	0.02	1.8	0.08	8.6
Cal Ver 4	2.92	0.23	7.8	0.13	4.6	0.14	4.8	0.30	10.2
Cal Ver 5	6.67	0.49	7.3	0.18	2.7	0.12	1.8	0.53	8.0
LowControl	0.32	0.02	7.6	0.01	3.9	0.0	0.0	0.03	8.5
HighControl	3.52	0.26	7.4	0.0	0.0	0.16	4.4	0.30	8.6

b. Linearity/assay reportable range:
The reportable range of the NEPHROCHECK® AKIRisk Score is 0.04 - 10.0. The markers that go into the score were assessed and found to be linear. However, the AKIRisk Score itself is not expected to be linear.

Hook effect was evaluated at AKIRisk Score values up to 250. High AKIRisk Score samples were evaluated in replicates of 28. Hook effect was defined as results falling below the peak values of the highest calibrator. No high dose hook effect was observed for AKIRisk Score at these values.

C. Traceability, Stability, Expected values (controls, calibrators, or methods):

Traceability:

The Astute140 Meter is factory calibrated. ASTUTE140® Meter calibration is based on two parameters: fluorescent intensity and linear positioning of the Meter's optics.

Internal standard solutions were developed by the sponsor using purified TIMP-2 and IGFBP-7. These standard solutions are used to make secondary calibrator materials for standardizing the production of the NEPHROCHECK® Test kits. The secondary calibrator materials are used to make working calibrators that are used to verify NEPHROCHECK® Control and Cal Vers values.

Value Assignment: Controls and Cal Vers:

The Cal Vers and Controls which are comprised of the two biomarkers are prepared gravimetrically. The Cal Vers and Controls are value assigned using the secondary calibrators. Individual biomarker values for each lot are embedded on a RFID card that is specific for each lot number.

The NEPHROCHECK® test kit open vial stability and the test cartridge open pouch stability protocols were reviewed and found acceptable. The results

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support test kit stability of 16 weeks. Results support open pouch test cartridge stability of 30-50% RH and 64-77°F (18-25°C) for 30 minutes.

The real time stability study protocol and acceptance criteria were reviewed for the NEPHROCHECK® Controls and Cal Verifiers and found acceptable. Results support stability of 16 weeks at -4 to 39.2°F to (-20 to 4°C). Open vial stability study protocol and acceptance criteria for the NEPHROCHECK® Controls and NEPHROCHECK® Calibration Verifiers were reviewed and found acceptable. Results support open vial stability for the Controls and Cal Vers is 24 hours.

The study protocol and acceptance criteria for sample stability was reviewed and found acceptable. Results support stability of the urine supernatant up to 5 hours at 64.4-77°F (18-25°C).

d. Detection limit:

Limit of Blank (LoB), Limit of Detection (LoD), and Limit of Quantitation (LoQ) studies were performed on three lots of NEPHROCHECK® test kits in accordance with CLSI EP17-A.

LoB Test Protocol

LoB was evaluated for AKIRisk Score using 3 urine samples that were treated to remove native levels of TIMP-2 and IGFBP-7. The samples were analyzed from 6 runs over 3 days for a total of 72 replicates per lot. The LoB was defined as the concentration at which there is a 95% probability that the sample does not yield an AKIRisk Score due to the absence of TIMP-2 and IGFBP-7.

LoD Test Protocol

LoD was evaluated on 6 low samples derived from apparently healthy donors with AKIRisk Score values ranging from the LoB to 4 times the LoB using 36 NEPHROCHECK® Tests from 3 lots for a total of 216 replicates. The LoD was calculated non-parametrically.

LoO Test Protocol

LoQ was determined by comparing the LoD study results against limits developed to ensure quantitative AKIRisk Score test results. Results demonstrated that the total error is less than the LoD. Therefore, the LoQ = LoD.

The studies support the following limits of detection for the AKIRisk Score:

LoB = 0.0002 LoD = 0.002 LoQ = 0.002

The reportable range of the AKIRisk Score is 0.04 - 10.0. The LoQ is below the reportable range. Therefore, this LoQ supports the analytical validity of the NEPHROCHECK® test at the clinical cutoff of > 0.3 AKIRisk Score and for the claimed reportable range.

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e. Analytical specificity:

Interference studies

Interference studies were conducted according to CLSI EP-7A2 using pooled human urine samples to determine whether the presence of potential interferents may interfere with the AKIRisk Score test results. Interferents were selected from medications, contrast agents, plasma expanders, other urine constituents, isoforms of TIMP and IGFBP, and other biomarkers which have been reported as elevated in the literature in AKI. The endogenous urine constituents were evaluated at 3 concentrations (low, mid-range and high). Exogenous substances were tested at low and high concentrations that were determined as the maximum amount eliminated in 24 hrs (low) and three times this concentration (high). Where the urinary excretion information was not available from literature, or other sources (specifically the drugs), the concentrations were determined as the maximum therapeutic dosage per liter of urine (low) and at three times this concentration (high). All other substances were evaluated at low and high concentrations. All samples were tested in replicates of 32, and the recovery of the AKIRisk Score in the presence of possible interferents calculated in comparison to the corresponding control sample. Interference was defined as any interferents that exhibited >±10% interference in the AKIRisk Score test result.

The tables below summarize the results.

Contrast Agents

Test Substance	High Test Conc. mg/L	Interference
Visipaque/Iodixanol	4,941	No
Omniscan/Gadodiamide	177	No
Omnipaque/Iohexol	14,085	No
Magnevist/Gadopentate	422	No
Optiray/Ioversol	4,944	No

Plasma Expanders

Test Substance	High Test Conc. mg/L	Interference
Dextran 40	22.2	No
Pentastarch	8.9	No
Hetastarch	5.9	No

Drugs and Other Substances

Test Substance	High Test Conc. mg/L	Significant Interference
Acetaminophen	200.72	No
Acetone	696.96	No
Acetylcysteine	1,664.54	No
Acetyl salicylic acid (Aspirin)	652.18	No
Acyclovir	52	No
Albumin	1,250	Yes
Albuterol	0.40	No
Amiodarone	6.08	No
Ammonia	1,000	No
Amoxicillin	75.27	No
Amphotericin	81.9	No
Ascorbic acid	29.94	No
Atorvastatin	80	No
Bicarbonates	2940	No
Bilirubin, conjugated	72.07	Yes
Bumetanide	30	No
Caffeine	59.81	No
Caspofungin	86.1	No
Cefepime	9.36	No
Ceftriaxone	810.30	No
Cephalexin	116.94	No
Ciprofloxacin	10.01	No
Clopidogrel	225	No
Dexmedetomidine (Precidex)	0.21	No
Diltiazem (Cardizem)	43.2	No
Dopamine	0.9	No
Doripenem (Dobrimax)	1,050	No
Epinephrine	6	No
Ethacrynic acid	19.4	No
Ethanol	4,000	No
Fenoldopam	483.84	No
Fentanyl	100	No
Fluconazole	74.97	No
Fluvastatin	80	No
Furosemide	59.87	No
Gentamicin	10.04	No
Glucose	9,908.8	No
Hemoglobin	2000	No
Heparin	21.42	No
Hydralazine	600	No
Hydrochlorothiazide	6.02	No
Hydrocodone	0.20	No
Hydrocortisone	720	No
Ibuprofen	500.25	No
Insulin	0.003	No
Ketorolac	165.6	No
Lansoprazole	90	No
Linezolid	48	No
Lisinopril	0.30	No
Lorazepam	1.00	No
Low Molecular Weight Heparin	30	No
Mannitol	600	No
Metformin	39.99	No
Methylene blue	3.89	Yes
Metolazone	60	No
Metoprolol	5	No
Metronidazole	119.87	No
Midazolam	1.14	No
Morphine	0.5	No
Moxifloxacin	1200	No
Nitroglycerin	0.0237	No
Norepinephrine	204	No
Omeprazole	6.00	No
Ondanesteron	0.11	No
Pancuronium	8.4	No
Pantoprazole (Protonix)	85.2	No
Phenobarbital	100.10	No
Phenylephrine	30	No
Pravastatin	80	No
Prednisone (Prednisolone)	3.00	No
Propofol	16.01	No
Ranitidine	6.00	No
Riboflavin	12	No
Rocuronium	126	No
Theophylline	39.96	No
Tobramycin	24.06	No
Torsemide	12	No
Urobilinogen, synthetic	12	No
Valproic Acid	499.25	No
Vancomycin	100	No
Vasopressin	5	No
Vecuronium	21	No
Warfarin (Coumadin)	10.02	No

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Common Urine Constituents

Test Substance	High Test Conc. mg/L	Significant
		Interference
Calcium	600	No
Chloride	5,600	No
Creatinine	1,800	No
Magnesium	240	No
Phosphate	2,800	No
Potassium	4,000	No
Sodium	3,600	No
Sulfate	4,800	No
Urea	23,000	No
Uric Acid	700	No

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Protein	High TestConc. mg/L	SignificantInterference
Insulin like growth factor-Binding Protein 1(IGFBP-1)	0.1	No
Insulin like growth factor-Binding Protein 2(IGFBP-2)	0.25	No
Insulin like growth factor-Binding Protein 3(IGFBP-3)	1.2	No
Insulin like growth factor-Binding Protein 4(IGFBP-4)	1.2	No
Insulin like growth factor-Binding Protein 5(IGFBP-5)	1.2	No
Insulin like growth factor-Binding Protein 6(IGFBP-6)	1.2	No
Insulin like growth factor 1 (IGF-1)	1.5	No
Insulin like growth factor 2 (IGF-2)	1.5	No
Cysteine-rich motor neuron 1 protein (CRIM1)	1.2	No
Agrin	1.2	No
Serine protease HTRA1 (HTRA1)	1.2	No
Insulin-like growth factor binding protein-like1 (IGFBP-1) (IGFBPL-1 (IGFBPL1)	1.2	No
Metalloproteinase inhibitor 1 (TIMP-1)	3	No
Metalloproteinase inhibitor 3 (TIMP-3)	2.5	No
Metalloproteinase inhibitor 4 (TIMP-4)	0.6	No
matrix metalloproteinase-2 (MMP-2)	0.03	No
matrix metalloproteinase-9 (MMP-9)	0.03	No

Potential Cross-Reactive Proteins

Potential Biomarkers Elevated in AKI

Biomarker	High TestConc. mg/L	SignificantInterference
Cystatin C	2.6	No
Interleukin-18 (IL-18)	0.001	No
Kidney Injury Molecule 1(KIM 1)	0.015	No
Liver Type Fatty Acid Binding Protein (L-FABP)	0.6	No
N-acetvH3-D-glucosaminidase (NAG)	$4.4 x10^{-5}$	No
Neutrophil gelatinase associated lipocalcin(NGAL)	3	No
Pi-Glutathione s-transferase (p-GST)	0.05	No

No interference was observed from contrast agents, plasma expanders, urine constituents not stated above, isoforms of TIMP-2 and IGFBP-7, or other potential biomarkers reported in the literature as being elevated in AKI.

Urine albumin at concentrations above 1250 mg/L interferes with test results. Bilirubin at concentrations above 72.1 mg/L exhibits interference with test results.

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Methylene blue at concentrations above 0.49 mg/L interferes with test results. These limitations are included in the labeling.

The effect of pH on AKIRisk Scores around and above the cutoff using samples with AKIRisk Score of 0.3 and 6.7 (at the higher end of ranges for TIMP-2 and IGFBP-7) was evaluated. Pooled human urine samples targeting these AKIRisk Scores were adjusted to target pH values of approximately 4, 6, 8, and 10. There was no effect from pH. The recommended pH range for samples is 4.2 - 9.9.

The effect of specific gravity on AKIRisk Scores around and above the cutoff using samples with AKIRisk Score of 0.3 and 6.9 (at the higher end of ranges for TIMP-2 and IGFBP-7) was evaluated. Pooled human urine samples targeting these AKIRisk Scores were adjusted to specific gravity of 1.001, 1.015 ±0.005, and > 1.0035. There was no effect from specific gravity on the AKIRisk Score. The recommended specific gravity range for samples is 0.998 - 1.038.

Assay cut-off: f.

The clinical study in M.3 below demonstrates that an AKIRisk Score > 0.3, when used in conjunction with clinical evaluation, aids in the risk assessment for moderate or severe acute kidney injury in patients who currently have or have had within the past 24 hours acute cardiovascular and or respiratory compromise and are ICU patients within twelve hours of patient assessment.

2. Comparison studies:

a. Method comparison with predicate device:

Not applicable.

b. Matrix comparison:

Not applicable. The NEPHROCHECK® Test is for human urine only.

3. Clinical studies:

The clinical performance of the NEPHROCHECK® Test at the cutoff of AKIRisk Score > 0.3 was evaluated in 2 clinical studies (Study A and Study B). Each of the 2 clinical studies was a multicenter prospective study in the intended use population at geographically diverse sites in the US. The intended use population was comprised of patients experiencing or having experienced within the past 24 hours acute cardiovascular or respiratory compromise and that were patients in the ICU, and these patients were followed for duration of the study (3 days). Patients with known moderate or severe acute kidney injury (e.g., RIFLE I, F, or KDIGO stage 2 or 3) were excluded from enrollment. Study A included 23 sites and enrolled 519 patients of which 408 completed the 3-day study and are denoted the evaluable cohort. Study B included 6 sites and enrolled 153 patients of whom 126

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completed the 3-day study and are denoted the evaluable cohort. Unevaluable patients (Study A = 111 patients and Study B = 27 patients) were unevaluable because the patients did not complete the 3 day study due to removal of catheter or discharge from the ICU. Final diagnoses were adjudicated by an independent panel of expert nephrologists using the practice standards as "AKI" (moderate or severe AKI present) or "No AKI" (no moderate or severe AKI present) within 12 hours of enrollment. Urine specimens were collected at enrollment. For Study A, AKIRisk Score results were tested at 3 independent laboratories. For Study B, AKIRisk scores were tested at 1 laboratory. Adjudicators were blinded to the site diagnoses and AKIRisk Score results. Clinical performance data comparing AKIRisk score to final diagnosis (below) are provided for the evaluable cohorts. Exclusion of the unevaluable patients did not affect the conclusions of the study.

AKIRisk Score	AKI Status		Total Number ofNEPHROCHECKTest Results
	AKI	No AKI
AKIRISK Score > 0.3	65 (16.0%)TP	182 (44.7%)FP	247
AKIRISK Score ≤ 0.3	6 (1.5%)FN	154 (37.8%)TN	160
Total Number ofNEPHROCHECK TestResults	71	336	407

Study A/Laboratory 1

Study A/Laboratory 2

	AKI Status	Total Number of
AKIRisk Score	AKI	No AKI	NEPHROCHECKTest Results
AKIRISK Score > 0.3	64 (15.7%)TP	172 (42.3%)FP	236
AKIRISK Score < 0.3	7 (1.7%)FN	164 (40.3%)TN	171
Total Number ofNEPHROCHECK TestResults	71	336	407

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Study A/Laboratory 3

		AKI Status
AKIRisk Score	AKI	No AKI
AKIRISK Score > 0.3	66 (16.2%)TP	186 (45.7%)FP	252
AKIRISK Score ≤ 0.3	5 (1.2%)FN	150 (36.9%)TN	155
Total Number ofNEPHROCHECK TestResults	71	336	407

Study B

AKIRisk Score	AKI Status		Total Number ofNEPHROCHECKTest Results
	AKI	No AKI
AKIRISK Score > 0.3	22 (17.5%)TP	48 (38.1%)FP	70
AKIRISK Score ≤ 0.3	7 (5.6%)FN	49 (38.9%)TN	56
Total Number ofNEPHROCHECKTest Results	29	97	126

Test Clinical Performance Characteristics Study A

	Laboratory 1		Laboratory 2		Laboratory 3
Statistic	Value	95% CI	Value	95% CI	Value	95% CI
Sensitivity (TPR)	0.92	0.85, 0.98	0.90	0.83, 0.97	0.93	0.87, 0.99
Specificity (TNR)	0.46	0.40, 0.51	0.49	0.43, 0.54	0.45	0.39, 0.50
Negative Predictive Value (NPV)	0.96	0.93, 0.99	0.96	0.93, 0.99	0.97	0.94, 1.00
Positive Predictive Value (PPV)	0.26	0.21, 0.32	0.27	0.21, 0.33	0.26	0.21, 0.32
False Positive Rate	0.54	0.49, 0.60	0.51	0.46, 0.57	0.55	0.50, 0.61
False Negative Rate	0.08	0.02, 0.15	0.10	0.03, 0.17	0.07	0.01, 0.13

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Statistic	Value	95% CI
Sensitivity (TPR)	0.76	0.60, 0.91
Specificity (TNR)	0.51	0.41, 0.60
Negative PredictiveValue	0.88	0.79, 0.96
Positive PredictiveValue	0.31	0.21, 0.42
False Positive Rate	0.49	0.40, 0.59
False Negative Rate	0.24	0.09, 0.40

Test Clinical Performance Characteristics Study B

a. Clinical Sensitivity:
See section M.3.
b. Clinical specificity:
See section M.3.
Other clinical supportive data (when a. and b. are not applicable): C.

4. Clinical cut-off:

The clinical study above demonstrates that an AKIRisk Score > 0.3, when used in conjunction with clinical evaluation, aids in the risk assessment for moderate or severe acute kidney injury in patients who currently have or have had within the past 24 hours acute cardiovascular and or respiratory compromise and are ICU patients within twelve hours of patient assessment.

5. Expected values/Reference range:

A reference range study was performed to determine the AKIRisk Score in two adult (at least 21 years of age) cohorts-an apparently healthy subject population, and individuals with stable chronic morbidities (without acute illness). Demographic and other information for the two cohorts is shown below.

To determine the AKIRisk Score reference range, a urine specimen from each subject was collected and split into 3 aliquots and sent to 3 independent laboratories for measurement. Non-parametric analysis of the AKIRisk Score was performed for the results from each laboratory. There was no statistical difference among the three laboratories. A wide range of AKIRISK™ scores (0.04-2.42) was observed in the apparently healthy subjects and subjects with stable chronic morbidities (without acute illness). The reference range was defined by the central 95th percentile (2.5%-97.5%) as described in CLSI guideline C28-A3. Patient demographics of the two cohorts are presented below:

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	Apparently HealthyCohort		Stable Chronic MorbidityCohort
	N,Mean,orMedian	%, (SD),or [IQR]	N,Mean, orMedian	%, (SD), or[IQR]
SexFemaleMale	191187	50.5%49.5%	191181	51.3%48.7%
RaceAmerican Indian*AsianBlack/African Amer.Native Hawaiian♦CaucasianOther	394313139	0.8%2.4%11.4%0.3%82.8%2.4%	61043330010	1.6%2.7%11.6%0.8%80.6%2.7%
EthnicityHispanicNon-Hispanic	43335	11.4%88.6%	33339	8.9%91.1%
Age (years)MeanMedian	5456	(17.3)(40-68)	6365	(14.7)(53-75)
BMI (kg/m²)Mean (SD)Median [IQR]	27.526.8	(5.87)[23.3-29.8]	30.829.8	(7.02)[26.2-34.5]

Demographic Characteristics of Apparently Healthy and Stable Chronic Morbidity Subjects

*Includes Alaskan Native, YIncludes Other Pacific Islander

Summarized results of the reference range study are below:

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		Site 1		Site 2		Site 3
Cohort	Gender	NumberofSubjects	ObservedAKI RiskScores*	NumberofSubjects	ObservedAKI RiskScores*	NumberofSubjects	ObservedAKI RiskScores*
ApparentlyHealthySubjects	Female	191	0.04 - 2.42	191	0.04 - 2.17	191	0.04 - 2.58
HealthySubjects	Male	185	0.04 - 2.33	187	0.04 - 2.10	187	0.05 - 2.35
HealthySubjects	All	376	0.04 - 2.33	378	0.04 - 2.10	378	0.04 - 2.35
Subjects withStableChronicMorbidities	Female	191	0.04 - 2.20	191	0.04 - 1.93	191	0.04 - 2.28
Subjects withStableChronicMorbidities	Male	179	0.06 - 2.23	181	0.06 - 2.13	181	0.06 - 2.36
Subjects withStableChronicMorbidities	All	370	0.05 - 2.20	372	0.04 - 1.98	372	0.04 - 2.28

Reference Ranges for Apparently Healthy Subjects and Subjects with Stable Chronic Morbidities by Testing Laboratory for Each of Three Testing Laboratories

*Central 95%

N. Instrument Name:

Astute140 Meter

O. System Descriptions:

1. Modes of Operation:

The Astute140 Meter is a small tabletop analyzer that can analyze one NEPHROCHECK® Test cartridge at a time. The operator must manually load the cartridge and remove it after the analysis has been completed.

1. Software:
  FDA has reviewed applicant's Hazard Analysis and software development processes for this line of product types:
1. Specimen Identification:
  The Meter can be interfaced with a laboratory information system for data management via USB or Ethernet. It also has a PS/2 Port for connection to an optional barcode reader or keyboard.

4. Specimen Sampling and Handling:

The Astute140 Meter can only accept one test cartridge at a time. Human urine is added to the kit Conjugate Vial and a 100 uL aliquot is dispensed onto the test cartridge for analysis.

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5. Calibration:

The Astute140 Meter is factory calibrated. Calibration is verified by the operator with an Electronic Quality Control cartridge and with liquid calibration verifiers.

The NEPHROCHECK® Calibration Verification Kit contains 5 materials with specified target concentration levels that evenly span the reportable ranges of the biomarkers used in the algorithm to verify the AKIRisk Score . The expected concentrations and standard deviations are printed on the NEPHROCHECK® Expected Values Card enclosed with the NEPHROCHECK® Calibration Verification Kit.

6. Quality Control:

Quality control is performed using an electronic QC cartridge and liquid low and high control materials. The electronic QC (EQC) is accomplished by comparing the output on the cartridge with a preset range of results. There are 2 internal QC lines on the EQC cartridge. The fluorescent intensities of the control lines must fall within a preset range for the test to be considered valid.

Liquid QC consists of a high and low control. The QC lot, expiration, and biomarker ranges for each of TIMP-2 and IGFBP-7 are entered into the Astute140 Meter with a RFID card enclosed with each Control Kit. The RFID card must be loaded prior to running QC. The Astute140 Meter also has a "lock out" feature that prevents assays from being performed if either the EQC or liquid QC fails. QC results may be printed or downloaded into a data manager or LIS.

P. Other Supportive Instrument Performance Characteristics Data Not Covered In The "Performance Characteristics" Section above:

The Astute 140 meter demonstrates compliance to EMC requirements including general requirements for laboratory use by meeting DIN EN 61326-1 as well as requirements for in vitro diagnostic medical equipment by meeting DIN EN 61326-2-6. In addition, the Astute 140 meter demonstrates compliance regarding information technology equipment and radio disturbances by meeting the requirements of DIN EN 55022, IEC/CISPR 22:2005.

The Astute140 Meter fulfilled EMI testing requirements for the RFID component under FCC part 15, subparts A, C, and I, ANSI C63:4 (2009), ANSI C95.1 (1992) and CISPR 16-4-2 (2003).

The Astute140 Meter underwent vibration testing based on EN 60068-2-64 and fall conditions based on EN 61010-1 to ensure that the meter met all reading, repeatability and functionality checks. The meter passed for all conditions.

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Q. Proposed Labeling:

The labeling is sufficient and it satisfies the requirements of 21 CFR Parts 801 and 809.

R. Identified Risks and Required Mitigations:

Identified Potential Risks	Required Mitigation Measures
Incorrect interpretation of test results	Special controls (1), (2), and (3)
Incorrect test results	Special control (3)

S. Benefit/Risk Analysis:

Summary
Summary of theBenefits (s)	The NEPHROCHECK® Test System aids in the risk assessment formoderate or severe AKI in critically ill patients within twelve hours ofpatient assessment for risk of AKI.
	The main benefit from the use of the NEPHROCHECK® Test is toprovide an opportunity to improve patient management for acutekidney injury by aiding physicians in identifying patients at risk forAKI. Identifying patients at risk for AKI may aid in the prevention ofprogression to CKD or possibly death and allow treatment topotentially reverse the injury to the kidney. Since AKI diagnosis iscurrently commonly delayed, identifying patients at higher risk beforedevelopment of AKI may allow for better management and treatmentand, therefore, serve an unmet medical need.
Summary of theRisk(s)	The potentially harmful events associated with the use of theNEPHROCHECK® Test are from inappropriate clinical decisionsbased on undetected instances of incorrect interpretation of test resultsand incorrect test results.
	A false negative test result may result in a patient being misclassifiedinto the non-high risk group, potentially resulting in a temporary delayin implementation of the kidney-sparing strategies for high riskpatients. Although the impact is potentially mitigated through labeling,(i.e., in the case of a low NEPHROCHECK® Test, (i.e. AKIRiskresult $≤$ 0.3) the user is instructed not to alter standard of caremanagement), should the user not follow the instructions and,instead act on the basis of a low test result, the duration of impact of afalse negative test result would only last until the results fromadditional testing (e.g., serum creatinine elevation, decrease in urineoutput) become available.
	A false positive test result could contribute to a patient beingmisclassified into a high risk group and could result in subjecting thepatient to further, unnecessary diagnostic testing (e.g., more frequent
	serum creatinine measurements or more frequent urine outputmonitoring) or temporary worsening of the primary disease state dueto, for example, temporary selection of less nephrotoxic treatments ordiagnostics that may be less efficacious. The duration of thepotential impact of a false positive test result would be for a limitedperiod of time since the subsequent diagnostic workup for patients athigh risk for AKI (e.g., monitoring of serum creatinine and urineoutput) soon clarify the patient's renal status.These risks can be mitigated via the special controls, including anintensive training program which includes the performance,limitations, and interpretation of the test.
Summary ofOther Factors	Acute kidney injury (AKI) is one of the more prevalent and seriousmorbidities in critically ill hospitalized patients and is associatedsubstantially increased mortality, morbidity, length of ICU stay and in-hospital cost as well as longer term health consequences, includingincreased risk for chronic kidney disease (CKD). Use of theNEPHROCHECK® Test System aids in avoidance of suboptimalpatient management or delay in optimal management of patients at riskfor AKI.
	In contrast to such conditions as myocardial infarction, AKI may notpresent with signs and symptoms sufficient to guide risk assessment.However, the literature states that "there is no reliable way for aclinician to use this information to establish a clear risk profile", and nolaboratory test method exists for risk assessment of AKI. Currently,there are no other in vitro diagnostic devices cleared or approved forthe NEPHROCHECK® Test's indicated use.
	Results of the clinical studies demonstrate that the NEPHROCHECK®Test is able to provide a benefit that outweighs risk for the intendeduse patient population. The magnitude of the benefit as well as theprobability that a patient for whom the device is intended willexperience a benefit was assessed through the clinical performance ofthe test in two studies.
	In summary, the test benefits outweigh the risks for use of the test as anadjunct to other clinical criteria to identify patients in the intended usepopulation who are at risk for moderate or severe AKI. The relativelylow specificity strongly suggests that some patients who are not at riskfor developing AKI may exhibit a positive test result. This reiterates thenecessity to consider other standard, accepted clinical criteria in theassessment of AKI risk in patients in the intended use population.
ConclusionsDo the probablebenefits outweighthe probable risks?	The ability of the NEPHROCHECK® Test to aid patients inidentifying patients at risk for moderate or severe AKI offerssignificant potential benefit. These patients can benefit from thekidney-sparing management strategies. Compared to these benefits
	the NEPHROCHECK® Test System poses risks that are adequatelymitigated by general and special controls. Thus, the probable benefitsoutweigh the probable risks.

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T. Conclusion:

The information provided in this de novo submission is sufficient to classify this device into class II under regulation 21 CFR 862.1220. FDA believes that special controls, along with the applicable general controls, provide reasonable assurance of the safety and effectiveness of the device type. This device is classified under the following:

Product Code: PIG

Device Type: Acute kidney injury test system

Class: II (special controls)

Regulation: 21 CFR 862.1220

(a) Identification. An acute kidney injury test system is intended to measure one or more analytes in human samples as an aid in the assessment of a patient's risk for developing acute kidney injury. Test results are intended to be used in conjunction with other clinical and diagnostic findings, consistent with professional standards of practice, including confirmation by alternative methods.

(b) Classification. Class II (special controls). Acute kidney injury test systems must comply with the following special controls:

Premarket notification submissions must detail an appropriate end user device training program that will be offered while marketing the device as part of your efforts to mitigate the risk of failure to correctly interpret test results.
As part of the risk management activities performed as part of your 21 CFR 820.30 design controls, you must document the appropriate end user device training program provided in your premarket notification submission to satisfy special control (1) that will be offered while marketing the device as part of your efforts to mitigate the risk of incorrect interpretation of test results.

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Robust clinical data demonstrating the positive predictive value, negative predictive value, sensitivity and specificity of the test in the intended use population must be submitted as part of the premarket notification submission.

Regulation Number and Section

§ 862.1220 Acute kidney injury test system.

(a)
Identification. An acute kidney injury test system is a device that is intended to measure one or more analytes in human samples as an aid in the assessment of a patient's risk for developing acute kidney injury. Test results are intended to be used in conjunction with other clinical and diagnostic findings, consistent with professional standards of practice, including confirmation by alternative methods.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Premarket notification submissions must detail an appropriate end user device training program that will be offered while marketing the device as part of your efforts to mitigate the risk of incorrect interpretation of test results.
(2) As part of the risk management activities performed as part of your 21 CFR 820.30 design controls, you must document the appropriate end user device training program provided in your premarket notification submission to satisfy special control 21 CFR 862.1220(b)(1) that will be offered while marketing the device as part of your efforts to mitigate the risk of incorrect interpretation of test results.
(3) Robust clinical data demonstrating the positive predictive value, negative predictive value, sensitivity and specificity of the test in the intended use population must be submitted as part of the premarket notification submission.