Mixed serum and plasma specimens from adult patients
Clinical specimens from adult patients were used to perform a method comparison study between the Envoy 500 HDL cholesterol application and a commercially available predicate method.
Method comparison; Clinical specimens; Serum and plasma
Clinical Evidence
Study Design
Population
Comparator
Key Endpoints
Method comparison study
Adult patients; Sample Size: 312
Commercially available competitive method
HDL cholesterol concentration (mg/dL)
Indications for Use
The Envoy® 500 HDL Cholesterol Reagent and Envoy® 500 HDL Calibrator are intended for use with the Envoy® 500 Chemistry System as a system for the quantitative determination of high density lipoprotein (HDL) cholesterol in serum and plasma. HDL cholesterol measurements are used in the diagnosis and treatment of lipid disorders (such as diabetes mellitus), atherosclerosis, and various liver and renal diseases, and for the assessment of the risk of developing cardiovascular disease. This reagent is intended to be used by trained personnel in a professional setting and is not intended for home use.
Device Story
Envoy 500 HDL Cholesterol Reagent is a two-part reagent kit used with the Envoy 500 Chemistry System; utilizes accelerator selective detergent methodology. Process: first step renders non-HDL cholesterol non-reactive; second step solubilizes HDL cholesterol using selective detergent to produce red chromogen. System measures absorbance to quantify HDL-cholesterol concentration. Used in clinical laboratory settings by trained personnel. Output provides quantitative HDL-cholesterol values; assists clinicians in diagnosing lipid disorders, atherosclerosis, liver/renal disease, and assessing cardiovascular risk. Benefits patient through accurate lipid profile monitoring.
Clinical Evidence
No clinical data. Performance established via bench testing. Precision: within-run CV 1.0-1.4%, total CV 1.8-2.0%. Linearity: 5-150 mg/dL (r=0.9998). Method comparison: 312 samples (serum/plasma) compared to predicate (y = 0.7 + 1.021x, r=0.991). Analytical specificity tested against ascorbic acid, bilirubin, hemoglobin, and triglycerides.
Technological Characteristics
Two-part reagent kit; accelerator selective detergent methodology. Energy source: photometric detection via Envoy 500 Chemistry System. Connectivity: integrated with Envoy 500 system. Sterilization: N/A (reagent). Software: embedded firmware for system control and calculation.
Indications for Use
Indicated for quantitative determination of HDL cholesterol in serum and plasma for adult patients to diagnose/treat lipid disorders, atherosclerosis, liver/renal diseases, and assess cardiovascular risk.
Regulatory Classification
Identification
A lipoprotein test system is a device intended to measure lipoprotein in serum and plasma. Lipoprotein measurements are used in the diagnosis and treatment of lipid disorders (such as diabetes mellitus), atherosclerosis, and various liver and renal diseases.
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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
ASSAY ONLY TEMPLATE
A. 510(k) Number:
k071706
B. Purpose for Submission:
New Device
C. Measurand:
HDL Cholesterol assay and calibrator
D. Type of Test:
Quantitative colorimetric test and calibrator
E. Applicant:
Clinical Data, Inc.
F. Proprietary and Established Names:
Envoy 500 HDL Cholesterol Reagent Kit
G. Regulatory Information:
1. Regulation section:
CFR 21 section 862.1475 - Lipoprotein test system
CFR 21 section 862.1150 - Calibrator
2. Classification:
Assay - Class I, subject to limitation to exemption 21 CFR 862.9(c)(4)
Calibrator - Class II
3. Product code:
LBS, JIT
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4. Panel:
Clinical Chemistry (75)
H. Intended Use:
1. Intended use(s):
See indications for use below.
2. Indication(s) for use:
The Envoy® 500 HDL Cholesterol Reagent and Envoy® 500 HDL Calibrator are intended for use with the Envoy® 500 Chemistry System as a system for the quantitative determination of high density lipoprotein (HDL) cholesterol in serum and plasma. HDL cholesterol measurements are used in the diagnosis and treatment of lipid disorders (such as diabetes mellitus), atherosclerosis, and various liver and renal diseases, and for the assessment of the risk of developing cardiovascular disease.
This reagent is intended to be used by trained personnel in a professional setting and is not intended for home use.
3. Special conditions for use statement(s):
For prescription use only
4. Special instrument requirements:
Envoy 500 Chemistry System
I. Device Description:
The Envoy® 500 HDL Cholesterol Reagent is a two-part reagent that is calibrated with the Envoy® 500 HDL Calibrator for use with the Envoy® 500 Chemistry System. The reagents consist of 27 mL boats of Envoy 500 HDL Cholesterol Reagent 1 and 9 ml bottles of reagent 2. Reagent 1 contains < 1,000 U/L cholesterol oxidase (E. coli), < 1,300 ppm U/L peroxidase (horseradish), < 1 mmol/L disodium N,N-bis(4-sulfobutyl)-m-toluidine, < 1 mmol/L accelerator, < 0.06% preservative, buffer, and other ingredients. HDL Cholesterol Reagent 2 contains < 1,500 U/L cholesterol esterase (Pseudomonas sp.), < 1 mmol/L 4-aminoantipyrine, < 2% detergent, < 0.15% restrainer, < 3,000 U/L ascorbate oxidase (Curcubita), < 0.06% preservative, buffer, and other ingredients. The calibrator contains a lyophilized human serum preparation of the various classes of lipoprotein including high density lipoproteins. The source materials in this product have been tested and found to be
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non-reactive for HBsAg and antibodies to HIV-1, HCV-2, and Hepatitis C Virus (HCV).
## J. Substantial Equivalence Information:
1. Predicate device name(s):
Genzyme Ultra N-geneous HDL Cholesterol Reagent and Genzyme Ultra N-geneous HDL Cholesterol Calibrator
2. Predicate K number(s):
k021316
3. Comparison with predicate:
| Similarities | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Intended use | Quantitative determination of HDL cholesterol in serum and plasma | Same |
| Analyte | HDL | Same |
| Calibrator | Lyophilized Human Serum | Same |
| Assay principle | Quantitative colorimetric | Same |
| Differences | | |
| --- | --- | --- |
| Item | Device | Predicate |
| Reportable Range | 5 to 150 mg/dL | 2.5 to 200 mg/dL |
## K. Standard/Guidance Document Referenced (if applicable):
CLSI EP-17A: Protocols for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline
CLSI EP-3T: Tentative Guidelines for Manufacturers for Establishing Performance Claims for Clinical Chemical Methods, Replication Experiment
## L. Test Principle:
This assay determines high density lipoprotein cholesterol through the accelerator selective detergent methodology. This procedure measures HDL-cholesterol in a two step reaction sequence. In the first step, non-HDL cholesterol is rendered non-reactive. In the second step, HDL cholesterol is solubilized using a selective detergent and reacts to produce a red chromogen. This method is based on accelerating the reaction of cholesterol oxidase (CO) with non-HDL unesterified cholesterol and dissolving HDL cholesterol selectively using a specific detergent. In the first reagent, non-HDL
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unesterified cholesterol is subject to an enzyme reaction and the peroxide generated is consumed by a peroxidase reaction with DSBmT yielding a colorless product. The second reagent consists of a detergent (capable of solubilizing HDL cholesterol), cholesterol esterase (CE), and chromagenic coupler to develop color for the quantitative determination of HDL cholesterol.
## M. Performance Characteristics (if/when applicable):
### 1. Analytical performance:
#### a. Precision/Reproducibility:
Estimates of imprecision were determined through the replicate analysis of two serum controls. The controls were assayed in triplicates in two independently calibrated runs separated by at least three hours. The daily protocol was repeated for a total of eight days using five Envoy 500 HDL Cholesterol Reagent boats on a single Envoy 500 Analyzer. Average results for the two controls were reported for every run. Estimates of within run and total imprecision were calculated and are shown below. The level 1 results from one of the runs were removed from the calculations.
| Sample | n | mean | Within Run | | Total | |
| --- | --- | --- | --- | --- | --- | --- |
| | | | 1SD | %CV | 1SD | %CV |
| Level 1 | 45 | 36.8 | 0.52 | 1.4% | 0.72 | 2.0% |
| Level 2 | 48 | 71.1 | 0.68 | 1.0% | 1.25 | 1.8% |
#### b. Linearity/assay reportable range:
Linearity was evaluated by testing 12 samples with equally spaced HDL concentrations ranging from 0 to over $170\mathrm{mg/dL}$. The samples were prepared by diluting a $3300\mathrm{mg/dL}$ human HDL Cholesterol concentrate with analyte stripped serum. The standards were then analyzed on the ENVOY 500 analyzer across 4 independently calibrated runs and compared to their dilution factors by least squares linear regression. The assay is linear across the reportable range of $5\mathrm{mg/dL}$ to $150\mathrm{mg/dL}$ HDL cholesterol as shown by mean regression residuals that are less than $1\mathrm{mg/dL}$ for all pools that describe this range and a correlation coefficient of 0.9998.
#### c. Traceability, Stability, Expected values (controls, calibrators, or methods):
Stability testing was performed by the manufacturer. The calibrators and reagents are stable until the expiration date on the label when stored as instructed.
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On board stability was performed on the Envoy 500 analyzer demonstrated that the calibrators and reagents are stable for 14 days when stored on board the Envoy 500 analyzer.
Calibrator set points are assigned by the calibrator manufacturer and are traceable to the CDC described reference method for the determination of HDL cholesterol. These calibrators are not traceable to the Cholesterol Reference Method Laboratory Network for HDL cholesterol results produced using the Envoy 500 instrument application.
d. Detection limit:
A limit of quantitation (LoQ) study was conducted based on procedures described in CLSI EP17-A. The limit of the blank (LoB) of 0.29 mg/dL and limit of detection (LoD) of 0.46 mg/dL were calculated as described in the CLSI document. The LoQ of 0.46 mg/dL was determined to be equal to the LoD and was calculated assuming a zero method bias and an acceptable error of 2 mg/dL. The LoQ is lower than the lower limit of usable range which is set at 5 mg/dL.
e. Analytical specificity:
The effects of potential interfering substances were tested by assaying spiked serum pools. A serum pool with an HDL concentration of approximately 55 mg/dL was prepared from individual patient specimens and divided into aliquots. All but one of the aliquots were spiked with interferants at the concentrations shown below. The unspiked and spiked pools were tested multiple times in a single analytical run on the Envoy 500. Substances that affect results by more than 3 mg/dL compared to the interferant free sample were reported as interfering substances in the package insert.
| Interfering Substance | Levels Tested |
| --- | --- |
| Ascorbic Acid | 0, 0.75, 1.5, 2.25, 3.0 mg/dL |
| Ditaurobilirubin | 0, 8, 16, 24, 32, 40 mg/dL |
| RBC hemolysate | 0, 40, 80, 120, 160, 200 mg/dL |
| Intralipid, 20% solution | 0, 80, 160, 240, 320, 400 mg/dL
0, 400, 800, 1200, 1600, 2000 mg/dL |
The ascorbic acid, ditaurobilirubin, and RBC hemolysate spiked samples all had a bias of less than 3 mg/dL compared to the unspiked sample. The results of triglyceride interference (performed with intralipid) resulted in the bias shown below.
Changes in
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| Triglyceride Concentration | Recoveries |
| --- | --- |
| 240 mg/dL | -3.3 at 52 mg/dL |
| 400 mg/dL | -5.4 at 52 mg/dL |
| 800 mg/dL | -1.5 at 54 mg/dL |
| 2000 mg/dL | +2.5 at 54 mg/dL |
f. Assay cut-off:
Not applicable
2. Comparison studies:
a. Method comparison with predicate device:
One hundred sixty serum and 152 plasma specimens were collected from individual adult patients. Sample concentrations ranged from 5 mg/dL to 158 mg/dL as measured by the predicate device. These specimens were randomized and assayed using both the Envoy 500 HDL cholesterol application and the predicate device. The results, which spanned the full reportable range of the device, were compared by least squares regression. Regression statistics for the combined serum and plasma specimens are shown below.
$$
y = 0.7 \mathrm{mg/dL} + 1.021 x \quad r = 0.991
$$
b. Matrix comparison:
Not applicable
3. Clinical studies:
a. Clinical Sensitivity:
Not applicable
b. Clinical specificity:
Not applicable
c. Other clinical supportive data (when a. and b. are not applicable):
Not applicable
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4. Clinical cut-off:
Not applicable
5. Expected values/Reference range:
HDL cholesterol results should be evaluated against the risk classifications established by the National Cholesterol Education Program (Adult Treatment Panel III).⁴ These classifications for adults are listed below.
| Risk Classification | Conventional Units | SI Units |
| --- | --- | --- |
| Low | < 40 mg/dL | < 1.04 mmol/L |
| High | ≥ 60 mg/dL | ≥ 1.55 mmol/L |
⁴ National Institutes of Health, National Cholesterol Education Program. Detection Evaluation and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III), Final Report. NIH Publication No. 02-5215, September 2002.
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.
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1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
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You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
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Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
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Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
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Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
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Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
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Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
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A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.