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510(k) Data Aggregation
(84 days)
Street Waltham, MA 02451
Re: K190266
Trade/Device Name: NeoLSD MSMS Kit Regulation Number: 21 CFR 862.1488
| NeoLSD MSMS Kit |
| Regulation: | 21 CFR 862.1488
The NeoLSD™ MSMS kit is intended for the quantitative measurement of the activity of the enzymes acid-9glucocerebrosidase (ABG), acid-sphingomyelinase (GAA), 8 galactocerebrosidase (GALC), agalactosidase A (GLA) and a-L-iduronidase (IDUA) in dried blood spots (DBS) from newborn babies. The analysis of the enzymatic activity is intended as an aid in screening newborns for the following lysosomal storage disorders (LSD) respectively; Gaucher Disease, Niemann-Pick A/B Disease, Krabbe Disease, Fabry Disease, and Mucopolyaccharidosis Type I (MPS I) Disease.
The NeoLSD MSMS test system uses mass spectrometry to quantitatively measure the activity of six lysosomal enzymes simultaneously from a dried blood spot sample. The NeoLSD MSMS test system is comprised of:
- NeoLSD MSMS kit, including substrates, internal standards, solutions and controls
- The QSight Instrument is comprised of:
QSight® 210 MD Mass Spectrometer O
QSight HC Autosampler MD Instrument Software O
QSight Binary Pump MD O
Simplicity Instrument control software: O
Simplicity Data Processing software (by sample): O
O PerkinElmer MSMS Workstation Data Processing Software
The NeoLSD MSMS kit evaluates enzyme activities by measuring the product generated when an enzyme reacts with a synthesized substrate to create a specific end product. The activities of the six lysosomal enzymes present in a 3.2 mm punch from a dried blood spot (DBS) are simultaneously measured by the NeoLSD MSMS kit. The punches are incubated with the assay reagent mixture which contains;
- six substrates, one corresponding to each lysosomal enzyme
- six stable-isotope mass-labeled internal standards (IS) each designed to chemically resemble each product generated
- . a buffer to maintain the reaction pH, and to carry inhibitors to limit activity from competing enzymes if present and additives to enhance the targeted enzyme reactions.
Here's a breakdown of the acceptance criteria and study information for the NeoLSD MSMS Kit, based on the provided document:
1. Table of Acceptance Criteria and Reported Device Performance
The document doesn't explicitly state acceptance criteria in a dedicated table for screening performance per se, but it details the analytical performance and implies that meeting the predicate device's performance characteristics for screening, along with established analytical limits, constitutes acceptance. The "Comparison Chart" on page 6 includes some comparable metrics between the proposed and predicate device.
Below is a table summarizing the reported analytical performance, with implied acceptance criteria that the device's performance should be within acceptable clinical/analytical ranges and comparable to the predicate device.
| Performance Metric | Acceptance Criteria (Implied/General) | Reported Device Performance (QSight System) |
|---|---|---|
| Reportable Range (µmol/L/h) | Generally, a sufficiently broad and clinically relevant range. | IDUA: 0.19 – 22.3GAA: 0.31 – 25.3ABG: 0.79 – 20.0GLA: 0.80 – 20.4ASM: 0.16 – 13.8GALC: 0.20 – 7.75 |
| Lower Limits of Measure (LoB, LoD, LoQ) (µmol/L/h) | Limits should be clinically relevant and allow for detection of low enzyme activity associated with LSDs. Imprecision at LoQ within specified CV% limits (ABG, GLA, IDUA <40%; ASM, GAA <30%; GALC <50%). | IDUA: LoB=0.044, LoD=0.13, LoQ=0.19GAA: LoB=0.080, LoD=0.31, LoQ=0.31ABG: LoB=0.114, LoD=0.79, LoQ=0.79GLA: LoB=0.519, LoD=0.80, LoQ=0.80ASM: LoB=0.046, LoD=0.16, LoQ=0.16GALC: LoB=0.120, LoD=0.20, LoQ=0.20 Imprecision (CV%) at LoQ: ABG (LoQ 0.79): No specific CV% provided at LoQ, but precision data for sample 1 (mean 1.05) shows Total variation CV% of 22.8% (within <40% target).ASM (LoQ 0.16): No specific CV% provided at LoQ. GALC (LoQ 0.20): No specific CV% provided at LoQ, but precision data for sample 1 (mean 0.27) shows Total variation CV% of 13.4% (within <50% target).IDUA (LoQ 0.19): No specific CV% provided at LoQ, but precision data for sample 1 (mean 0.76) shows Total variation CV% of 15.8% (within <40% target).GLA (LoQ 0.80): No specific CV% provided at LoQ, but precision data for sample 1 (mean 1.03) shows Total variation CV% of 16.1% (within <40% target).GAA (LoQ 0.31): No specific CV% provided at LoQ, but precision data for sample 1 (mean 0.95) shows Total variation CV% of 12.8% (within <30% target). |
| Linearity (Linear Range µmol/L/h) | Data should fulfill acceptance criteria of the study. | IDUA: 0.08 – 22.3GAA: 0.11 – 25.3ABG: 0.39 – 20.0GLA: 0.60 – 20.4ASM: 0.09 – 13.8GALC: 0.18 – 7.75 |
| Precision (Total Variation CV%) | Within acceptable analytical variability for newborn screening, generally below specific thresholds (e.g., <40% for ABG, GLA, IDUA; <30% for ASM, GAA; <50% for GALC). Ranges given in Comparison Chart hint at typical performance, e.g., 8.9%-15.8% for IDUA. | ABG: 10.7%-22.8%GALC: 7.4%-13.4%IDUA: 8.9%-15.8%GLA: 7.3%-16.1%GAA: 7.3%-12.8%ASM: 8.1%-14.5% |
| Screening Performance (Agreement with Predicate) | High agreement (e.g., all confirmed positive samples identified, minimal false positives/negatives) | Gaucher (ABG): 100% agreement (3 Positive with QSight, 3 Positive with TQD; 2487 Negative with both)Niemann-Pick A/B (ASM): 100% agreement (2 Positive with QSight, 2 Positive with TQD; 2488 Negative with both)Krabbe (GALC): 100% agreement (4 Positive with QSight, 4 Positive with TQD; 2486 Negative with both)MPS I (IDUA): 100% agreement (6 Positive with QSight, 6 Positive with TQD; 2484 Negative with both)Fabry (GLA): 100% agreement (6 Positive with QSight, 6 Positive with TQD; 2484 Negative with both)Pompe (GAA): 100% agreement (1 Positive with QSight, 1 Positive with TQD; 2489 Negative with both) |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size for Screening Performance Study: 2489 routine newborn samples + 12 archived confirmed LSD positive newborn Dried Blood Spot (DBS) specimens = 2501 samples.
- Data Provenance:
- Country of Origin: The study was conducted at a "US newborn screening laboratory (Site A)".
- Retrospective/Prospective: Primarily retrospective for the routine samples as they were "routine newborn samples". The 12 positive samples were "archived confirmed LSD positive newborn DBS specimens", making them retrospective as well. The device also mentions testing samples from newborns ≤ 48 hours old, common for newborn screening.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number of experts or their qualifications. It refers to the 12 archived confirmed LSD positive newborn DBS specimens as having a "confirmed" diagnosis. This implies clinical confirmation, likely by medical specialists and further diagnostic testing, but the specific process for establishing this ground truth (e.g., expert panel review of clinical, biochemical, and genetic data) is not detailed.
4. Adjudication Method for the Test Set
The document does not describe a formal adjudication method for the test set in terms of expert review for AI output. Instead, the study compares the screening results of the new device (QSight) against a predicate device (Waters Acquity TQD) and against retrospectively confirmed positive samples. The "ground truth" for the 12 positive samples was their established "confirmed" LSD status, not an adjudication process by experts specifically for this study.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
This is not applicable. The device is an in-vitro diagnostic kit for quantitative measurement of enzyme activity using mass spectrometry (MSMS), not an image-based AI system that assists human readers. The study involves comparing the performance of the new kit on one MSMS instrument (QSight) against its predicate on a different MSMS instrument (Waters Acquity TQD).
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, this study represents a standalone performance evaluation of the "NeoLSD MSMS Kit" on the "QSight Instrument" system. The kit/instrument system performs the quantitative measurement of enzyme activity. While a human laboratory technician operates the instrument and interprets the numerical results based on cut-off values, the core diagnostic output (enzyme activity) is determined by the automated system without subjective human interpretation of raw data fields that would typically be associated with "standalone AI" vs "human-in-the-loop" in other diagnostic contexts (e.g., radiology). The comparison is between two automated systems (QSight vs. TQD).
7. The Type of Ground Truth Used
The ground truth for the 12 positive samples was confirmed LSD diagnoses, which implies a combination of:
- Clinical diagnosis: Based on patient symptoms.
- Biochemical confirmation: Enzyme assays, metabolite analysis.
- Genetic confirmation: DNA sequencing to identify pathogenic variants.
For the 2489 routine newborn samples, the ground truth is implied to be their "routine" healthy status, where no LSD was suspected or later confirmed, and their performance was used to establish median values and cut-offs.
8. The Sample Size for the Training Set
The document does not explicitly mention a "training set" in the context of machine learning. The term "training set" is typically used for developing AI models. This device is a diagnostic kit based on mass spectrometry, not a machine learning algorithm that is "trained." Performance characteristics like expected values (means, medians, percentiles) were derived from a large population of 2488 (or 2489) routine newborn samples, which could be considered a reference population for establishing normal ranges and cut-offs.
- Expected Values (Reference Population): 2488 or 5041 (depending on the enzyme) de-identified residual DBS samples from routine newborn screening. (Page 7, Table "Expected Values")
9. How the Ground Truth for the Training Set was Established
As noted above, there's no explicit "training set" in the AI sense. However, the "Expected Values" table on page 7 lists statistics derived from "N=2488" and "N=5041" samples, which are described as de-identified residual DBS samples from routine newborn screening. These would represent a population assumed to be largely unaffected (normal controls) in terms of LSDs, allowing for the establishment of normal enzyme activity ranges, medians, and percentiles. The ground truth for these samples would be their implicit "normal" or "no confirmed LSD" status based on routine screening outcomes or lack of follow-up diagnoses.
Ask a specific question about this device
(212 days)
Street Waltham, MA 02451
Re: K173829
Trade/Device Name: NeoLSD MSMS kit Regulation Number: 21 CFR 862.1488
Person: Tel: 317 418-1735
Trade Name: NeoLSD MSMS Kit
Common Name: NeoLSD MSMS Kit
Regulation: 21 CFR 862.1488
The NeoLSD MSMS Kit is intended for the quantitative measurement of the activity of the enzymes acid-pglucocerebrosidase (ABG), acid-sphingomyelinase (ASM), acid-a-glucosidase (GAA), B-galactocerebrosidase (GALC), α-galactosidase A (GLA) and α-L-iduronidase (IDUA) in dried blood spots (DBS) from newborn babies. The analysis of the enzymatic activity is intended as an aid in screening newborns for the following lysosomal storage disorders (LSD) respectively; Gaucher Disease, Nieman-Pick A/B Disease, Pompe Disease, Fabry Disease, and MPS I Disease.
The NeoLSD MSMS test system uses mass spectrometry to quantitatively measure the activity of six lysosomal enzymes simultaneously from a dried blood spot sample. The NeoLSD MSMS test system is comprised of:
- NeoLSD MSMS kit, including substrates, internal standards, solutions and controls
- Waters TQD MSMS instrument comprised of,
a. Waters 1525 sample pump
b. Waters 2777c autosampler
c. Waters MassLynx v4.1 firmware C.
d. Power cables, tubing, syringes, connection cables - Waters NeoLynx v4.1 software and computer with monitor
- PerkinElmer MSMS Workstation Software
The NeoLSD MSMS kit evaluates enzyme activities by measuring the product generated when an enzyme reacts with a synthesized substrate to create a specific end product. The activities of the six lysosomal enzymes present in a 3.2 mm punch from a dried blood spot (DBS) are simultaneously measured by the NeoLSD MSMS kit. The punches are incubated with the assay reagent mixture which contains;
. six substrates, one corresponding to each lysosomal enzyme
. six stable-isotope mass-labeled internal standards (IS) each designed to chemically resemble each product generated
. a buffer to maintain the reaction pH, and to carry inhibitors to limit activity from competing enzymes if present and additives to enhance the targeted enzyme reactions.
The NeoLSD MSMS Kit is intended for the quantitative measurement of the activity of six lysosomal enzymes (acid-β-glucocerebrosidase (ABG), acid-sphingomyelinase (ASM), acid-α-glucosidase (GAA), β-galactocerebrosidase (GALC), α-galactosidase A (GLA), and α-L-iduronidase (IDUA)) in dried blood spots (DBS) from newborn babies. The analysis of enzymatic activity serves as an aid in screening newborns for Gaucher Disease, Niemann-Pick A/B Disease, Pompe Disease, Krabbe Disease, Fabry Disease, and MPS I Disease.
Here's an analysis of the acceptance criteria and the study that proves the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are generally implied by the performance metrics reported, such as linearity ranges, precision (reproducibility %CV), and LoQ values. The screening performance, particularly sensitivity and specificity, are key for a screening tool.
| Performance Characteristic | Acceptance Criteria (Implied) | Reported Device Performance (NeoLSD MSMS Kit) |
|---|---|---|
| Linear Range | Broad enough to cover physiological and pathological ranges | IDUA: 0.34 – 17.2 µmol/L/hGAA: 0.44 – 24.2 µmol/L/hABG: 0.69 – 20.1 µmol/L/hGLA: 0.97 – 20.9 µmol/L/hASM: 0.90 – 20.5 µmol/L/hGALC: 0.63 – 6.3 µmol/L/h |
| Lower Limit of Quantitation (LoQ) | Low enough to detect deficient enzyme activity (within acceptable CV%) | IDUA: 0.44 µmol/L/h (CV% at LoQ: 18.2%)GAA: 0.63 µmol/L/h (CV% at LoQ: 17.5%)ABG: 0.69 µmol/L/h (CV% at LoQ: 21.7%)GLA: 0.97 µmol/L/h (CV% at LoQ: 17.5%)ASM: 0.90 µmol/L/h (CV% at LoQ: 20.0%)GALC: 0.34 µmol/L/h (CV% at LoQ: 20.6%) |
| Reproducibility (%CV) | Within acceptable limits for a diagnostic assay (e.g., <20-30%) | Within-Laboratory CV% RangeIDUA: 4.7 – 6.9%GAA: 4.2 – 5.5%ABG: 11.6 – 13.8%GLA: 5.0 – 13.3%ASM: 7.3 – 11.0%GALC: 7.9 – 19.5%Between-Laboratory CV% RangeIDUA: 4.4 – 8.1%GAA: 3.5 – 7.6%ABG: 4.7 – 15.8%GLA: 5.6 – 8.4%ASM: 1.8 – 6.6%GALC: 2.1 – 7.0%Overall Reproducibility CV% RangeIDUA: 6.9 – 10.0%GAA: 5.6 – 9.4%ABG: 13.0 – 21.0%GLA: 8.6 – 15.7%ASM: 7.6 – 11.4%GALC: 9.3 – 20.7% |
| Sensitivity (overall) | High, to minimize false negatives in screening (e.g., >90%) | 92.9% (76.5%-99.1%) (excluding invalid and lost-to-follow-up, including 2 Fabry females that were false negatives) With female Fabry subjects excluded, the test system has no false negative results for any of the enzymes. |
| Specificity (overall) | High, to minimize false positives (e.g., >95%) | 99.4% (99.1%-99.6%) (excluding invalid and lost-to-follow-up) |
| False Positive Rate (overall) | Low, to minimize unnecessary follow-up (e.g., <5%) | 0.6% (0.4% - 0.9%) |
| False Negative Rate (overall) | Very low, critical for screening (e.g., <1%) | 7.1%* (0.9% - 23.5%) (*includes 2 Fabry females). When female Fabry subjects are excluded, the test system has no false negative results for any of the enzymes. |
| Interference | Minimal, or clearly identified and manageable | Several potential interferents identified (e.g., Glucose, Hematocrit, Hemoglobin, Triglycerides, EDTA), with their effects and implications described. For most, the interferences are not pronounced enough to impair affected/unaffected separation or occur at clinically irrelevant concentrations. Specific warnings are provided for high glucose, hematocrit, and triglyceride levels near cut-off values. |
Note: The document provides performance metrics, implying these are the acceptance criteria that the device has met or is expected to meet for its intended use as a newborn screening aid.
2. Sample Size Used for the Test Set and Data Provenance
-
Sample Size for Screening Performance Study:
- Routine Samples: 4011 newborn specimens (retrospective, 4 years old, used for follow-up of clinical status).
- Confirmed LSD Positive Samples (enriched): 30 newborn DBS specimens (from the site's biobank, ranging from 5.8 to 17.6 years of age).
- Total Test Set: 4041 specimens (4011 routine + 30 confirmed positive).
-
Data Provenance:
- Routine Samples: Retrospective routine newborn screening samples, 4 years old, from an EU (European) newborn screening laboratory.
- Confirmed LSD Positive Samples: From the site's biobank (likely the same EU lab), with ages ranging from 5.8 to 17.6 years.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document does not explicitly state the number or qualifications of experts used to establish the ground truth for the test set.
Instead, the ground truth for the 4011 routine samples was established based on:
- Clinical outcome: "Clinical outcome was used as a comparator for all samples, including the 4011 routine screening samples, as derived from the civil registry status and national hospital registry. Subject´s survival at 4 years of age without LSD diagnosis or clinical signs suggestive of an LSD was used as clinical confirmation of an unaffected newborn."
- For the 30 confirmed LSD positive samples: Their status was "known" as "confirmed LSD positive newborn DBS specimens."
Therefore, the ground truth relies on clinical follow-up data and prior confirmed diagnoses, rather than a panel of experts adjudicating each case for the study.
4. Adjudication Method for the Test Set
No explicit "adjudication method" in the sense of expert review (e.g., 2+1, 3+1) is described for the test set. The ground truth was established by:
- Clinical outcome and registry data for routine samples to determine "unaffected" status.
- Known (prior confirmed) diagnoses for the "confirmed positive" samples.
- Screening algorithm: For routine samples, those below the initial cut-off were re-tested in duplicate to classify as normal, presumptive positive, or invalid.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This device is a diagnostic kit that quantitatively measures enzyme activity, not an interpretative imaging AI tool that assists human readers. Therefore, the concept of "human readers improve with AI vs without AI assistance" does not apply here.
6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) was done
Yes, the screening performance study essentially represents a standalone (algorithm only) performance for the NeoLSD MSMS kit. The device measures enzyme activity, and the "screening results" (positive, negative, invalid) are derived directly from these quantitative measurements compared against predefined cut-off values and a re-testing algorithm. While a human laboratory technician performs the assay, the interpretation of the results as "screen positive" or "screen negative" is determined by the device's output and the established algorithm, without human interpretative judgment affecting the individual sample classification.
7. The Type of Ground Truth Used
The ground truth used was primarily:
- Outcomes data/Clinical Confirmation: For the 4011 routine samples, "Subject´s survival at 4 years of age without LSD diagnosis or clinical signs suggestive of an LSD was used as clinical confirmation of an unaffected newborn." This is a form of clinical outcome data.
- Pathology/Confirmed Diagnosis: For the 30 enriched samples, they were "confirmed LSD positive" specimens, indicating a definitive medical diagnosis.
8. The Sample Size for the Training Set
The document describes studies for establishing reference ranges and calibration, but it does not explicitly describe a "training set" in the context of machine learning model development. The development of this assay likely involved extensive analytical validation (e.g., linearity, LoQ, interference) and establishing reference ranges using large sample sets, which might be considered analogous to a training or development phase for defining assay parameters and cut-offs.
- Reference Range Establishment:
- EU site: 5041 newborn samples were tested to establish cut-off values. These were "retrospective routine newborn screening samples" from newborns 0-30 days of age.
- US Site A: 5251 newborn DBS specimens, newborns ≤ 4 days.
- US Site B: 5053 newborn DBS specimens, newborns ≤ 7 days.
These large cohorts were used to determine population distributions, medians, and percentiles to set initial and retest cut-off values. While not a "training set" for an AI algorithm, they serve a similar purpose in defining the operational parameters for the device's classification logic.
9. How the Ground Truth for the Training Set Was Established
Given that there isn't a "training set" for an AI model, the "ground truth" for establishing the reference ranges and cut-offs was based on:
- Population Distribution: Statistical analysis of enzyme activity levels in large cohorts of presumably healthy newborns (5041 from EU, 5251 from US Site A, 5053 from US Site B).
- Expert-defined Percentiles: The initial cut-off values were based conservatively on "0.1 - 0.3 percentile of enzyme activity distribution and converted to a percentage of population median activity," which reflects expert consensus on appropriate thresholds for screening. The "retest cut-off values were set 5% lower from the initial cut-off percentage."
This process is standard for establishing normal ranges and screening cut-offs for diagnostic assays and involves statistical methods and clinical expert judgment in setting initial thresholds.
Ask a specific question about this device
(548 days)
Regulation:
- 21 CFR 862.1488
-
- Classification:
Class II (special controls)
this de novo submission is sufficient to classify this device into class II under regulation 21 CFR 862.1488
Class: | II (special controls) |
| Regulation: | 21 CFR 862.1488
The SEEKER System, including the SEEKER Instrument and the SEEKER LSD Reagent Kit-IDUA|GAA|GBA|GLA for use on the SEEKER Instrument, is intended for quantitative measurement of the activity of a-L-iduronidase, a-D-glucosidase, Bglucocerebrosidase and a-D-galactosidase A from newborn dried blood spot specimens as an aid in screening newborns for Mucopolysaccharidosis Type I, Pompe, Gaucher and Fabry diseases. Reduced activity of these enzymes may be indicative of these lysosomal storage diseases. The enzymes measured using the SEEKER LSD Reagent Kit-IDUA|GAA|GBA|GLA and their associated lysosomal storage diseases are listed below.
| Enzyme (abbreviation) | Disease |
|---|---|
| α-L-iduronidase (IDUA) | Mucopolysaccharidosis Type I (MPS I) |
| α-D-glucosidase (GAA) | Pompe |
| β-glucocerebrosidase (GBA) | Gaucher |
| α-D-galactosidase A (GLA) | Fabry |
The SEEKER System employs digital microfluidic technology to measure multiple lysosomal enzymatic activities quantitatively from newborn dried blood spot specimens. The following components are provided:
-
- SEEKER Instrument (including USB and power cables), Desktop PC with monitor, keyboard, mouse, and the Spot Logic software.
-
- SEEKER LSD Reagent Kit IDUA|GAA|GBA|GLA containing enzyme specific substrate reagents, dried blood spot extraction buffer, reaction stop buffer, 4 levels of calibrators and quality control dried blood spots containing 4 levels of quality control (OC) material. Each Reagent Kit contains sufficient consumables for 1440 tests. The contents of the kit are listed below:
| Component | Contents | Quantity |
|---|---|---|
| Quality controldried blood spots | QC-Base Pool (QCBP) | 1x15 spots |
| QC-Low (QCL) | 1x15 spots | |
| QC-Medium (QCM) | 1x15 spots | |
| QC-High (QCH) | 1x15 spots | |
| Enzyme substrates | IDUA | 9x100 µL |
| GAA | 9x100 µL | |
| GBA | 9x100 µL | |
| GLA | 9x100 µL | |
| Calibrators | Calibrant A (CALA) | 9x50 µL |
| Calibrant B (CALB) | 9x50 µL | |
| Calibrant C (CALC) | 9x50 µL | |
| Calibrant D (CALD) | 9x50 µL |
Other components needed to run tests include the following:
| Component | Contents | Quantity |
|---|---|---|
| Other Reagents | Extraction Buffer (EXT) | 9 x 30 mL |
| Filler Fluid | 9 x 10 mL | |
| Cartridge | SEEKER cartridge | 1 x 36 |
The composition of the enzyme reagents and buffers are summarized below:
| Reagent (Description) | Composition |
|---|---|
| IDUA(α-L-iduronidase substrate) | 2 mM 4-MU-α-L-iduronide sodium salt3mM D-saccharolactone0.04 M acetate buffer, pH 3.520 mM methyl β-cyclodextrin0.01% Tween20 |
| GAA(α-D-glucosidase substrate) | 5 mM 4-MU-α-glucopyranoside12 µM acarbose0.04 M acetate buffer, pH 3.820 mM methyl β-cyclodextrin0.01% Tween20 |
| GBA(β-glucocerebrosidase substrate) | 16 mM 4-MU-β-glucopyranoside0.05 M/0.1M citrate phosphate buffer, pH 5.20.01% Tween201.5% sodium taurocholate |
| GLA(α-D-galactosidase A substrate) | 10 mM 4-MU-α-galactopyranoside145 μM N-acetyl galactosamine0.04 M acetate buffer, pH 4.620 mM methyl β-cyclodextrin0.01% Tween20 |
| Stop Buffer STB(reaction stopping buffer) | 0.6 M NaHCO3, pH 11.0 in 0.04% Tween 20 |
| Extraction Buffer EXT(dried blood spot extraction buffer) | 0.1% Tween 20 in water |
| Filler Fluid(medium for droplet movement) | 0.1% Triton X-15 in 5cSt silicone oil |
The Seeker Calibrators are supplied as part of the SEEKER LSD Reagent Kit -IDUA|GAA|GBA|GLA. The calibrators consist of 4 levels of aqueous preparation of 4methylumbelliferone sodium salt (4-MU) in 0.6M sodium bicarbonate buffer, pH 11.0 with 0.01% Tween 20. The concentration of 4-MU in each of the 4 calibrators is indicated in the table below:
| Calibrator Level | Concentration of 4-MU |
|---|---|
| Calibrant A (CAL A) | 0.0375 µM |
| Calibrant B (CAL B) | 0.0750 µM |
| Calibrant C (CAL C) | 0.1500 µM |
| Calibrant D (CAL D) | 0.3000 µM |
The quality control dried blood spots include 4 levels of control material: OC Low (QCL), QC Medium (QCM) and QC High (QCH). The composition of the 4 quality control dried blood spot (DBS) is summarized below. QCBP is used to fill empty wells on a cartridge.
| Quality Control Level | Composition |
|---|---|
| QCBP | Heat inactivated human serum, adjusted to ~50% hematocritusing human red blood cells |
| QCL | 5% cord blood and 95% heat inactivated serum, adjusted to~50% hematocrit using human red blood cells |
| QCM | 50% cord blood and 50% heat inactivated serum adjusted to~50% hematocrit using human red blood cells |
| QCH | Human umbilical cord blood, adjusted to ~50% hematocritusing human red blood cells |
The enzymatic activity values for the quality control DBS measured by the manufacturer are given on the lot specific quality control certificate included in each assay kit for all levels except QCBP. Each laboratory should establish its own mean and acceptable ranges for the quality control materials.
3. SEEKER Cartridges
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- Finnipipette Novus 8-channel automatic pipette 1-10 uL
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- Finnipipette Novus 1-channel automatic pipette 10-100 uL
The SEEKER System is a device designed for quantitative measurement of the activity of α-L-iduronidase (IDUA), α-D-glucosidase (GAA), β-glucocerebrosidase (GBA), and α-D-galactosidase A (GLA) from newborn dried blood spot specimens. This serves as an aid in screening newborns for Mucopolysaccharidosis Type I (MPS I), Pompe, Gaucher, and Fabry diseases.
Here's an analysis of the acceptance criteria and the study that proves the device meets those criteria:
1. Acceptance Criteria and Reported Device Performance
The acceptance criteria for the SEEKER System are implicitly defined by the analytical and clinical performance standards required for its De Novo classification as a Class II device with special controls. These controls mandate thorough demonstration of performance characteristics, including clinical validity, reference intervals, carry-over, detection limits, and imprecision. The clinical validity is primarily demonstrated by the false positive and false negative rates observed in the pivotal clinical study.
Table: Acceptance Criteria (Implied by Regulatory Requirements) and Reported Device Performance
| Performance Characteristic | Acceptance Criteria (Implied) | Reported Device Performance (Pivotal Phase Study) | Notes |
|---|---|---|---|
| Clinical Validity (False Positive Rate) | Acceptable false positive rates to minimize unnecessary confirmatory testing and emotional burden. | IDUA: 0.035%GAA: 0.092%GBA: 0.047%GLA: 0.097% | These rates are considered acceptable, particularly given the benefits of early detection and the fact that newborns with "presumed normal" results after risk assessment were not followed up, potentially leading to an overestimation of the false positive rate. |
| Clinical Validity (False Negative Rate) | Acceptable false negative rates to ensure affected newborns are detected and receive timely therapy. | IDUA: 0%GAA: 0%GBA: 0%GLA: 0% (Note: 2 newborns that would have been FN at 7.0µmol/L/hr cutoff were TP at 8.0µmol/L/hr cutoff. Labeling specifies known limitations for female Fabry and late-onset Pompe). | The reported 0% false negative rate for IDUA, GAA, and GBA is based on active surveillance and the assumption that early-onset cases would be reported. However, some limitations are disclosed in the labeling, acknowledging potential false negatives due to clinical variability (e.g., late-onset Pompe, female Fabry patients). The adjustment of cutoffs over time also indicates complexities in achieving a perfect 0% FN rate. The note about GLA false negatives suggests that the 0% reported might be dependent on the specific cutoff used at the time. |
| Imprecision (Reproducibility) | Reproducibility across different instruments, reagent lots, and days, within acceptable limits. (No explicit %CV target stated, but general medical device standards suggest low CVs for reliable quantitative assays). | IDUA: 14.2% - 28.5% CV (depending on concentration)GAA: 12.0% - 17.0% CVGBA: 15.7% - 38.0% CVGLA: 9.4% - 16.3% CV | These CVs are generally considered acceptable for screening assays, especially at lower concentrations where biological variability or technical limitations might be higher. The CLSI EP5-A3 guideline was followed. |
| Linearity/Reportable Range | Linear response over the intended measurement range, covering normal and disease-associated values. | IDUA: 2.77 to 50.75 µmol/L/hGAA: 2.18 to 94.66 µmol/L/hGBA: 2.14 to 73.24 µmol/L/hGLA: 4.88 to 153.74 µmol/L/h. Max deviation from linearity <10%. | Acceptable linearity was demonstrated. Outliers were noted but did not impact overall linearity claims, though their presence highlights the importance of robust outlier handling in routine testing. |
| Detection Limits (LoQ) | Limit of Quantitation (LoQ) should be below or at relevant clinical cutoffs to ensure accurate measurement in the critical low activity range. | IDUA: LoQ = 2.77 µmol/L/h (some clinical cutoffs were below this, e.g., High Risk 1.5 µmol/L/h)GAA: LoQ = 2.18 µmol/L/hGBA: LoQ = 1.85 µmol/L/hGLA: LoQ = 4.88 µmol/L/h (some clinical cutoffs were below this, e.g., 14+ days High Risk 3.0 µmol/L/h) | The LoQ values are provided. A significant limitation noted is that some clinical cutoffs for IDUA and GLA were below the LoQ, meaning that results in this critical range might not be reliably quantifiable, introducing an element of uncertainty in diagnosis for values between LoQ and these lower cutoffs. This is explicitly recognized as a limitation in the study findings. |
| Analytical Specificity | Minimal interference from common endogenous and exogenous substances. | Most common interferents (bilirubin, galactose, glucose, EDTA, heparin, intralipid) showed <+10% bias. IDUA specific interferences: total protein at >88 mg/mL and hematocrit at 66% caused significant negative bias; heparin increased imprecision. | Generally good, but specific interferences identified for IDUA (high protein, high hematocrit, heparin) are crucial for laboratories to consider. These are included in the package insert. |
| Carry-over | Demonstrate minimal or no significant impact from carry-over. | Most assays showed minimal bias (<10%). GLA showed up to 27% bias in one specific condition, leading to a recommendation for retesting. | Carry-over was identified for GLA under specific conditions (high GLA sample preceding a borderline sample), leading to a specific retesting recommendation in the package insert. This directly addresses the identified risk. |
The studies described predominantly cover the analytical performance requirements (reproducibility, linearity, detection limits, analytical specificity, carry-over) and the clinical performance (false positive/negative rates).
2. Sample Size Used for the Test Set and Data Provenance
The primary clinical effectiveness study (pivotal phase) involved screening 105,599 newborns.
Data Provenance: The study was performed over 24 months at a public state health laboratory that performs newborn screening. This implies the data were collected in the United States. The study was prospective in nature, as it involved actively screening newborns using the device over a defined period (pivotal phase 18 months). A preliminary study, prior to the pilot/pivotal studies, used approximately 13,000 presumed normal de-identified specimens and 29 known affected specimens, suggesting a mix of retrospective (de-identified) and potentially prospective collection for the known affected cases.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the "number of experts" or their specific "qualifications" involved in establishing the ground truth for the clinical test set in a centralized, adjudicatory manner (e.g., as consensus readers for imaging). Instead, the ground truth was established through confirmatory diagnostic methods and clinical follow-up within the standard newborn screening program.
For patients referred for follow-up:
- "Babies considered to still be at high risk for the screened condition after the risk assessment were referred for confirmatory testing."
- "Confirmed positive specimens must have a diagnosis based on confirmatory diagnostic methods or clinically meaningful information regarding the status of the subject must be obtained."
The "risk assessment" itself was performed by the laboratory, and would involve experienced personnel (e.g., laboratory directors, genetic counselors, metabolic specialists). While not explicitly listed as "experts establishing ground truth," these individuals make the critical decisions leading to confirmatory diagnosis. The state public health laboratory also had an active surveillance program to track false negative results, which likely involves experts in metabolic diseases.
4. Adjudication Method for the Test Set
The adjudication method for the clinical test set was an elaborate, multi-step process ingrained in the newborn screening workflow of the state health laboratory:
- Initial Screening: DBS cards were tested in singlicate.
- Retesting for Borderline Results: DBS with at least one enzyme below the borderline cutoff were retested in duplicate.
- Visual Outlier Evaluation: The laboratory evaluated retest results for "visual outliers." If found, additional testing was performed.
- Average Calculation: The average of valid retest results (excluding visual outliers) was calculated.
- Risk Assessment: If the average was below the high-risk cutoff, a risk assessment was performed by the laboratory. This assessment included review of other newborn screening enzyme results, sample quality, transfusion status, health status, transit time, gestational age, family history, and age at sample collection.
- Referral for Confirmatory Testing: Babies still considered at high risk after the risk assessment were referred for confirmatory diagnostic methods.
- Presumed Normal: Babies with an average above the high-risk cutoff after retest, or those not referred after risk assessment, were presumed normal.
This is a complex, stepwise adjudication process, rather than a simple 2+1 or 3+1 consensus. It involves a combination of algorithmic cutoffs, repeat testing, visual inspection, and comprehensive clinical review.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done
No, an MRMC comparative effectiveness study was not performed for the SEEKER System. This device is a quantitative enzymatic activity assay for newborn screening, not an imaging-based diagnostic aid or an AI system intended to be used directly by human readers in an interpretive capacity. Therefore, the concept of "how much human readers improve with AI vs without AI assistance" does not apply in the context of this device. The SEEKER System performs the assay autonomously using digital microfluidic technology.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, the primary function of the SEEKER System is standalone (algorithm only) in measuring enzyme activities. The results are reported as quantitative values (micromoles of 4-MU produced / liter of blood / hour of incubation).
However, the "human-in-the-loop" component comes into play with the interpretation of these quantitative results within the newborn screening program's workflow:
- The device generates raw data, which is then processed by its software (Spot Logic).
- The laboratory applies specific cutoff values (high risk, borderline), which were adjusted and refined during the study period by human experts based on observed performance and factors like age.
- Human judgment is involved in the "risk assessment" process for borderline cases.
- Human decision-making leads to referral for confirmatory testing.
So, while the initial measurement is standalone, the screening decision (positive/negative/retest/referral) is a combination of the device's quantitative output and a multi-step human-defined protocol.
7. The Type of Ground Truth Used
The ground truth used for determining true positives and true negatives in the clinical study was primarily based on confirmatory diagnostic methods and clinical follow-up/outcomes data.
- For positive cases, the "True Positives" are those confirmed by "other confirmatory diagnostic methods." This implies biochemical, genetic, or clinical diagnoses consistent with the respective lysosomal storage diseases.
- For negative cases, the "Presumptive False Positives" are those referred but not confirmed, or those deemed normal after risk assessment. The absence of reported false negatives through the active surveillance program and the assumption that early-onset cases would be clinically identified also contribute to the ground truth for true negatives (i.e., those who screened negative and did not later develop symptoms or receive a diagnosis).
8. The Sample Size for the Training Set
The document does not explicitly delineate a "training set" in the context of typical machine learning or AI models with a distinct number of samples. This device is an enzymatic assay system, not an algorithm that undergoes iterative training on a dataset.
However, the "cutoffs" used by the laboratory for interpreting the results can be thought of as parameters that were "tuned" or "trained" based on observational data:
- "A preliminary study was performed by the public state health laboratory prior to the pilot/pivotal studies to establish initial cutoff values. Approximately 13,000 presumed normal de-identified specimens and 29 known affected specimens were analyzed using the proposed device."
- "The cutoff values were adjusted during the course of the study in order to reduce the false negative and false positive rate and also to take into account seasonal changes..."
These initial 13,029 specimens and the ongoing refinement using data from the 48,813 newborns in the pilot phase could be considered analogous to a "training" or "development" dataset for establishing the operational parameters (cutoffs) of the screening algorithm.
9. How the Ground Truth for the Training Set was Established
For the "training" data (preliminary study and pilot phase used for cutoff adjustments):
- Known affected specimens (29 samples): These likely had their diagnosis confirmed by established diagnostic methods (e.g., enzyme assays, genetic testing) or clinical presentation from relevant patient populations prior to being used in the preliminary study.
- Presumed normal de-identified specimens (13,000 samples): These were likely samples from healthy newborns collected and de-identified, implicitly considered "normal" based on the absence of a disease diagnosis through routine clinical channels.
- Ongoing Adjustment: During the pilot and pivotal phases, the clinical outcomes (confirmatory diagnoses, absence of symptoms) informed the continuous adjustment of cutoffs, acting as a feedback mechanism for refining the test's interpretive ground truth. The "active surveillance program" for false negatives also served to validate the accuracy of the negative screening decisions.
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