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510(k) Data Aggregation
(87 days)
The MeMed BV test is an automated semi-quantitative immunoassay that measures three non-microbial (host) proteins (TRAIL, IP-10, and CRP) in adult and pediatic serum and venous whole blood samples and is intended for use in conjunction with clinical assessments and other laboratory findings as an aid to differentiate bacterial from viral infection. MeMed BV is indicated for use in patients presenting to the emergency department or urgent care center and with samples collected at hospital admission from patients with suspected acute bacterial or viral infection, who have had symptoms for less than seven days. The MeMed BV test generates a numeric score that falls within discrete interpretation bins based on the increasing likelihood of bacterial infection.
The MeMed BV® ("BV test" or the "test") is an In-Vitro-Diagnostic device that measures in parallel the blood concentrations of TRAIL, IP-10 and CRP. The test consists of an automated analyzer with built-in hardware and software that conduct chemiluminescence based analyte measurements of patient serum and venous whole blood samples and their computational integration (MeMed Key®), and a disposable cartridge that contains the reagents and controls needed to detect the analytes of interest (MeMed BV® cartridge). The test generates an answer to each sample, with a test run time of approximately 15 minutes.
Here's a breakdown of the acceptance criteria and the study proving the device meets them, based on the provided FDA 510(k) summary for MeMed BV:
The MeMed BV test is intended for use in conjunction with clinical assessments and other laboratory findings as an aid to differentiate bacterial from viral infection in patients presenting to the emergency department or urgent care center, or with samples collected at hospital admission, who have had symptoms for less than seven days. The device generates a numeric score that falls within discrete interpretation bins based on the increasing likelihood of bacterial infection.
1. Table of Acceptance Criteria and Reported Device Performance
The 510(k) summary details various analytical performance studies and a clinical study to support the expanded indications for use. Key acceptance criteria and reported performance include:
| Test Category | Acceptance Criteria | Reported Device Performance |
|---|---|---|
| Analytical Performance | ||
| Limit of Quantitation (LoQ) | Total Error (TE): TRAIL < 30%, IP-10 < 40%, CRP < 30% | Serum Test Script: - TRAIL: Max TE at LLOQ (15 pg/mL) was 21%. (One sample at X0.8 showed 51% TE for TRAIL, but the defined LLOQ concentration level (X1.0) met criteria).- IP-10: Max TE at LLOQ (100 pg/mL) was 15%.- CRP: Max TE at LLOQ (1 mg/L) was 9%.Whole Blood (WB) Test Script: - TRAIL: Max TE at LLOQ (15 pg/mL) was 10%.- IP-10: Max TE at LLOQ (100 pg/mL) was 14%.- CRP: Max TE at LLOQ (1 mg/L) was 10%. All defined LLOQ concentrations for both serum and WB met the acceptance criteria. |
| Reproducibility/Precision | Measurands (TRAIL, IP-10, CRP): CV ≤ 15% (for concentrations above LoQ).MeMed BV® Test Score: SD < 12.5 score units. | Serum Samples: All reported repeatability, intermediate precision, and reproducibility CVs for TRAIL, IP-10, and CRP were ≤ 11.3%. All reported SDs for the MeMed BV Score were ≤ 6.6 score units. WB Samples (Precision): All reported CVs for TRAIL, IP-10, and CRP were ≤ 12.0%. All reported SDs for the MeMed BV Score were ≤ 3 score units. All reported values met the pre-established acceptance criteria. |
| Lot-to-Lot Reproducibility | Measurands (TRAIL, IP-10, CRP): CV ≤ 15% (for concentrations above LoQ).MeMed BV® Test Score: SD < 12.5 score units. | All reported between lot CVs for TRAIL, IP-10, and CRP were ≤ 10.7%. All reported between lot SDs for the MeMed BV Score were ≤ 2.3 score units. All reported values met the pre-established acceptance criteria. |
| Linearity | Allowable deviation from linearity (ADL) < 15% or 10 mg/L for CRP; 15% or 10 pg/mL for TRAIL; 20% or 50 pg/mL for IP-10. | Serum Samples: Max observed % deviation from linearity was 6.8% (TRAIL).Whole Blood Samples: Max observed % deviation from linearity was 8.6% (TRAIL). All results were within acceptance criteria. |
| Hook Effect | No hook effect observed up to tested concentrations (TRAIL – 1,000 pg/mL, IP-10 – 10,000 pg/mL, CRP – 500 mg/L). | All concentrations up to TRAIL – 1,000 pg/mL, IP-10 – 10,000 pg/mL, and CRP – 500 mg/L showed higher signal than the ULOQ sample. No hook effect observed. |
| Carry Over | WB Samples: Difference between average score of high score sample run after low score sample and high score sample baseline average score of ≤ 12.5 score units. Difference between average score of low score sample run after high score sample and low score sample baseline average score of ≤ 12.5 score units. | Maximal difference in score obtained for high score sample was 1.4 score unit difference. No carry-over occurred with the MeMed BV test. |
| Interference/Cross Reactivity | 95% Confidence Interval for bias within +/- 12.5 score units for all interferents and cross-reactants. | Previously submitted data (K222332) demonstrated this. The recovery of TRAIL, IP-10 and CRP were within the predetermined +/- 10% of the sample nominal concentration. Assays are tolerant to high HAMA concentrations and no interference/cross-reactivity from tested compounds. |
| Correlation to Reference Standard (New Calibration Scheme vs. Legacy) | 1. <5% of samples have MCC scores deviating from legacy calibration scores by an amount placing them in non-adjacent bins.2. Pearson correlation > 0.95.3. Absolute bias < 12.5 units at bin cutoff points (10, 35, 65, 90). | 1. The study successfully met the clinically relevant criterion (no paired samples assigned to nonadjacent bins).2. Pearson correlation was 1 (Deming Regression slope=1.00, 95% CI 0.99-1.00; intercept 0.00-0.06).3. Estimated bias at cutoff points ranged from -0.57 to -0.55, with 95% CIs well within +/- 12.5 units. New MCC is equivalent to legacy calibration. |
| Sample In-Use Stability (WB) | Allowable handling conditions demonstrated from blood draw to sample input. | The minimal acceptable period of time was approximately 140 minutes for TRAIL viral sample 1. Formal in-use stability of WB sample type established at 120 minutes prior to testing on analyzer. |
| Clinical Studies | ||
| Matrix Equivalency (WB vs. Serum) | Passing & Bablok Regression: Slope in range of 0.9-1.1; Intercept in range of (-5) to 5. | Slope: 1.00 (95% CI 0.99-1.00). Intercept: 0.00-0.06. Both predefined acceptance criteria for analytical equivalency were fulfilled. |
| Bin Impact Analysis (WB vs. Serum) | <5% of paired samples demonstrating a score deviation that causes a patient to be assigned to a nonadjacent bin. | No paired samples demonstrated a score deviation that caused the patient to be assigned to a nonadjacent bin. This strengthens the conclusion of analytical equivalency. |
| Diagnostic Accuracy (Simulated WB against Adjudication) | Cochran-Armitage (CA) Test for trend: Reject null hypothesis (no trend of increasing probability of bacterial infection with higher test score) for ≥ 95% of simulations.Likelihood Ratio (LR): 95% CI should exclude 1 for some bins (preferably Bins 1,2,4,5) for ≥ 95% of simulations. | All-inclusive cohort: CA p<0.001 for 100% of 100K simulations. CI of LR for exactly 4 bins (1,2,4,5) excluded 1 in 100% of simulations.Suspected cohort: CA p<0.001 for 100% of 100K simulations. CI of LR for exactly 4 bins (1,2,4,5) excluded 1 in 99.98% of simulations (0.02% had all 5 bins exclude 1). Both acceptance criteria passed, validating diagnostic accuracy of simulated WB samples. |
2. Sample Sizes Used for the Test Set and Data Provenance
-
Analytical Performance Test Sets:
- LoQ: Samples used per test script (serum and whole blood) and two cartridge lots. Specific number of unique samples not detailed, but each was tested three times on three non-consecutive days with results across 4 concentration levels.
- Reproducibility/Precision & Lot-to-Lot Reproducibility: Panel of 4 scores (representing various infection statuses) for serum, and 3 scores for WB. Serum study involved 90 replicates per panel member across 3 labs. WB study involved runs on 5 different analyzers. Lot-to-lot used 18 replicates per panel member.
- Linearity: Five replicates of eleven dilutions for each measurand.
- Hook Effect: 4 samples with varying high concentrations.
- Carry Over: Two whole blood samples (one high score, one low score) run in sequences.
- Correlation to Reference Standard (Calibration Scheme Comparison): 100 serum specimens.
-
Clinical Study Test Set (Perseverance Study):
- Sample Size: 216 prospectively recruited subjects.
- Data Provenance: Multi-center study from 5 medical centers (2 in the US, 3 in Israel).
- Retrospective/Prospective: Prospective.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The document states that the Apollo study (NCT04690569), which provided the basis for the original serum MeMed BV clearance (K210254), used a rigorous reference standard based on etiological adjudication by experts provided with comprehensive patient data.
- Number of Experts: Not explicitly stated how many experts for the adjudication, but plural "experts" is used.
- Qualifications of Experts: Not explicitly stated but they were responsible for "etiological adjudication" which implies medical professionals with expertise in differential diagnosis of infections (e.g., infectious disease specialists, clinical microbiologists, relevant clinical physicians). The term "comprehensive patient data" suggests they had access to clinical, laboratory, and other relevant information.
4. Adjudication Method for the Test Set
The ground truth for the clinical utility (diagnostic accuracy) of the MeMed BV was based on an adjudication-based reference standard from the Apollo study. The document doesn't specify the exact adjudication method (e.g., 2+1, 3+1), but implies a consensus or majority decision by the experts based on comprehensive patient data.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, an MRMC comparative effectiveness study was not mentioned as part of this 510(k) submission. This submission primarily focuses on analytical equivalency of whole blood samples to serum samples and simulated diagnostic accuracy, not human reader improvement with AI assistance. The MeMed BV is an in vitro diagnostic device that provides a numeric score, not an imaging AI algorithm designed to assist human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
The device's performance, represented by its numeric score and bin assignment, is inherently standalone in terms of its output. The analytical performance evaluations (LoQ, precision, linearity, etc.) and the clinical study's simulation of diagnostic accuracy (comparison of MeMed BV score to adjudicated ground truth) assess the algorithm's performance directly. The device is intended to be used "in conjunction with clinical assessments and other laboratory findings," meaning its score is an aid, but its performance itself is measured as a standalone diagnostic aid.
7. The Type of Ground Truth Used
- For Analytical Performance: Ground truth is established by the known concentrations of analytes in controls/calibrators, established reference methods, or through robust statistical measurements.
- For Clinical Performance (Diagnostic Accuracy Simulation): The ground truth was an etiological adjudication by experts provided with comprehensive patient data from the Apollo study. This is a form of expert consensus based on extensive clinical information.
8. The Sample Size for the Training Set
The document does not specify a separate "training set" sample size for the MeMed BV algorithm because it is an in vitro diagnostic device that measures specific biomarkers and computationally integrates them. The algorithm's "training" or development would have occurred prior to the studies presented for this 510(k) (which are validation studies). The previous 510(k) (K222332) for the serum-only version would have covered the initial development and validation, and this submission focuses on extending the indication to whole blood samples.
The phrase "new Master Calibration Curve (MCC)" suggests a change to the underlying measurement calculation, which might involve a new calibration dataset for the algorithm, but this is an analytical validation, not a "training set" in the sense of machine learning model development. For the calibration scheme comparison, 100 serum specimens were used as a test set.
9. How the Ground Truth for the Training Set Was Established
As noted above, a distinct "training set" for the MeMed BV algorithm itself (as a machine learning model might have) is not described in this regulatory submission. For the analytical validations:
- Calibration: Established against reference standards and through controlled experiments to define the relationship between measured signals (RLU) and analyte concentrations. The "Master Calibration Curve" is related to how the instrument translates raw signals into quantitative measurements and ultimately into the BV score.
- Clinical Utility (Reference Standard): If earlier development involved classification algorithms, their "ground truth" would have similarly been derived from expert adjudication or robust clinical diagnoses in previous studies (like the Apollo study mentioned, which provided the original basis for serum clearance). The current "clinical studies" section primarily describes validation of the expanded indication.
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(233 days)
The MeMed BV test is an automated semi-quantitative immunoassay that measures three non-microbial (host) proteins (TRAIL, IP-10, and CRP) in adult and pediatric serum samples and is intended for use in conjunction with clinical assessments and other laboratory findings as an aid to differentiate bacterial from viral infection. The MeMed BV is indicated for use in patients presenting to the emergency department or urgent care center and with samples collected at hospital admission from patients with suspected acute bacterial or viral infection, who have had symptoms for less than seven days. The MeMed BV test generates a numeric score that falls within discrete interpretation bins based on the increasing likelihood of bacterial infection.
The Med BV® ("BV Test" or the "Test") is an In-Vitro-Diagnostic device that measures in parallel the blood concentrations of TRAIL, IP-10 and CRP. The Test consists of an automated analyzer with built-in hardware and software that conduct chemiluminescencebased analyte measurements of patient serum samples and their computational integration (MeMed Key®), and a disposable cartridge that contains the reagents and controls needed to detect the analytes of interest (MeMed BV® cartridge). The Test generates an answer to each sample, with a test run time of approximately 15 minutes.
The provided text is a 510(k) Summary for a modified medical device, the MeMed BV. It describes the device, its intended use, technological characteristics, and a comparison to a previously cleared predicate device. However, it explicitly states that the purpose of this specific 510(k) notice is for a modification to the already cleared device, primarily concerning an alternative manufacturing process for a component (Antibody-Alkaline Phosphatase conjugation chemistry) and a new buffer formulation.
The document does not provide detailed acceptance criteria or the full study findings that would typically be presented for a de novo clearance or a 510(k) for a novel device. Instead, it refers to prior studies for the original cleared device and asserts that the modified device's performance is equivalent.
Therefore, many of the requested details about acceptance criteria, detailed study results, sample sizes, ground truth establishment, and expert involvement are not present in the provided document for this specific submission (K222332). The document focuses on demonstrating that the modification does not negatively impact the performance, based on studies referencing the original device's validation.
Here's a breakdown of what can be extracted and what is missing:
1. Acceptance Criteria and Reported Device Performance
The document states: "The modified version of the MeMed BV has been tested according to the methods, protocols, and acceptance criteria used to support the previously 510(k)-cleared device. These methods apply to the device that is the subject of this Special 510(k) and were used in verification and validation ("V&V") of the modifications. The studies tested the performance of the measurement procedure for each individual measurand - CRP, IP-10, and TRAIL, as well as the performance of the measurement procedure for the MeMed BV® test score that is based on the computational integration of the three measurands. Testing included precision/reproducibility, LoQ, linearity, hook effect, interference/cross-reactivity, and method comparison testing. All testing indicated equivalent performance to the 510(k)-cleared MeMed BV."
This document does not list the specific numerical acceptance criteria or detailed results for performance metrics like sensitivity, specificity, or AUC as it is a Special 510(k) for a modification, not an initial clearance. It merely states that the modified device's performance was equivalent to the previously cleared predicate device, and the types of tests conducted for V&V.
| Performance Metric (Types of Studies Conducted) | Acceptance Criteria (Not Explicitly Stated in Document) | Reported Device Performance (as stated in document) |
|---|---|---|
| Precision/Reproducibility | (Presumed to be within pre-defined limits for predicate) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| Limit of Quantitation (LoQ) | (Presumed to be within pre-defined limits for predicate) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| Linearity | (Presumed to be within pre-defined limits for predicate) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| Hook Effect | (Presumed to be within pre-defined limits for predicate) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| Interference/Cross-Reactivity | (Presumed to be within pre-defined limits for predicate) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| Method Comparison | (Presumed to demonstrate agreement with predicate) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| Measurement of TRAIL, IP-10, CRP | (Quantitative limits for immunoassays, not specified) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
| MeMed BV® test score | (Algorithm output performance, not specified) | Indicated equivalent performance to 510(k)-cleared MeMed BV |
2. Sample Size Used for the Test Set and Data Provenance
The document does not provide details on the specific sample sizes used for the test set or the data provenance (country of origin, retrospective/prospective). It refers to the validation done for the previously cleared device.
3. Number of Experts Used to Establish Ground Truth and Qualifications
The document does not provide details on the number or qualifications of experts used to establish ground truth because it's a submission for a modification, not a de novo clearance. Ground truth would have been established during the original device's clearance.
4. Adjudication Method for the Test Set
The document does not provide details on any adjudication method.
5. Multi Reader Multi Case (MRMC) Comparative Effectiveness Study
The document does not mention or describe an MRMC comparative effectiveness study or any effect size related to human readers improving with AI vs. without AI assistance. The MeMed BV is an in-vitro diagnostic (IVD) device measuring biomarkers, not an AI imaging or diagnostic algorithm designed to assist human readers in image interpretation.
6. Standalone (Algorithm Only) Performance Study
The document describes the device as an "automated semi-quantitative immunoassay that measures three non-microbial (host) proteins (TRAIL, IP-10, and CRP)... The MeMed BV test generates a numeric score that falls within discrete interpretation bins." This indicates it is a standalone algorithm in the sense that it processes the biomarker measurements and outputs a score. However, it's not a standalone AI performance study in the context of, for example, a diagnostic imaging algorithm being compared to expert interpretation. It's a measurement technology combined with a computational integration.
The performance studies mentioned ("precision/reproducibility, LoQ, linearity, hook effect, interference/cross-reactivity, and method comparison testing") are typical for standalone IVD device performance.
7. Type of Ground Truth Used
The document indicates the device "is intended for use in conjunction with clinical assessments and other laboratory findings as an aid to differentiate bacterial from viral infection." This strongly implies that the ground truth for the original validation studies would have been established based on clinical diagnoses, confirmed microbiological cultures/PCR, and a thorough review of patient outcomes and medical records by expert clinicians. However, the exact methodology for ground truth establishment for the original device is not detailed in this document.
8. Sample Size for the Training Set
The document does not provide any information regarding the sample size for a training set. As this is an IVD device and not explicitly an AI/machine learning model where "training sets" are typically discussed, this information might not be presented in this format, or it would have been part of the original device's clearance. The "computational integration" aspect implies an algorithm, but training details are not given.
9. How the Ground Truth for the Training Set Was Established
Similarly, the document does not provide any information on how the ground truth for any training set was established.
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(210 days)
The DiaSorin LIAISON® MeMed BV® is an automated in vitro diagnostic semi-quantitative assay that uses chemiluminescent immunoassay (CLIA) technology to measure three non-microbial (host) proteins (TRAIL, IP-10, and CRP) in adult and pediatric serum samples and is intended for use in conjunction with clinical assessments and other laboratory findings as an aid to differentiate bacterial from viral infection. The LIAISON® MeMed BV® assay is indicated for use in patients presenting to the emergency department or urgent care center and with samples collected at hospital admission from patients with suspected acute bacterial or viral infection, who have had symptoms for seven days or less. The LIAISON® MeMed BV® assay generates a numeric score that falls within discrete interpretation ranges based on the increasing likelihood of bacterial infection. The assay has to be performed on the automated LIAISON® XL Analyzer.
The DiaSorin LIAISON® MeMed BV® Control Set is intended for use as assayed quality control to monitor the performance of the DiaSorin LIAISON® MeMed BV® assay. The performance characteristics of the LIAISON® controls have not been established for any other assays or instrument platforms different from the automated LIAISON® XL Analyzer. The control set is intended for in vitro diagnostic use in a professional laboratory only.
The LIAISON MeMed BV assay consists of three individual chemiluminescence immunoassay (CLIA) for quantitative determination of TRAIL, IP-10, and CRP. The LIAISON MeMed BV test result is a score between 0 and 100 derived from computational integration of the measurements of the three proteins TRAIL, IP-10, and CRP, where low scores are indicative of viral infection and high score of bacterial infection. All three reagent packs must be the same lot and present at the same time on the same instrument used for sample testing. All three reagent packs are individually calibrated and quality controlled. Specimens are to be assigned to the MMBV assay protocol where all three reagent packs will be utilized to provide combined results and a final score.
The TRAIL reagent pack uses a monoclonal antibody for capture of TRAIL and a polyclonal antibody for the detection of TRAIL. The assay incubates sample, calibrator or control with assay buffer and paramagnetic particles coated with a monoclonal antibody that specifically recognizes the TRAL. Following the incubation, an isoluminol conjugated polyconal antibody that recognizes TRAIL is then added to the reaction and incubated. The unbound conjugate is removed with a wash step. Starter reagents are then added and a flash chemiluminescent reaction is initiated. The light signal is measured by a photomultiplier as relative light units (RLU) and is proportional to the concentration of TRAL present in the calibrators, controls or samples. The result of the TRAIL reagent pack is only used to calculate a final LIAISON MeMed BV Score and should not be used individually for diagnosis.
The IP-10 reagent pack uses a monoclonal antibody for the capture of IP-10 and a polyclonal antibody for the detection of IP-10. The assay incubates sample, calibrator or control with assay buffer and paramagnetic particles coated with a monoclonal antibody that specifically recognizes the IP-10. Following the incubation, an isoluminol conjugated polyclonal antibody that recognizes IP-10 is then added to the reaction and incubated. The unbound conjugate is removed with a wash step. Starter reagents are then added and a flash chemiluminescent reaction is initiated. The light signal is measured by a photomultiplier as relative light units (RLU) and is proportional to the concentration of IP-10 present in the calibrators, controls or samples. The result of the IP-10 reagent pack is only used to calculate a final LIAISON MeMed BV Score and should not be used individually for diagnosis.
The CRP reagent pack uses monoclonal antibodies for capture and detection of CRP. First the patient serum sample is pre-diluted 1:196 with assay buffer. The assay incubates the pre-diluted sample, calibrator or control with assay buffer and paramagnetic particles coated with a monoclonal antibody that specifically recognizes the CRP. Following the incubation, an isoluminol conjugated monoclonal antibody that recognizes CRP is then added to the reaction and incubated. The unbound conjugate is removed with a wash step. Starter reagents are then added and a flash chemiluminescent reaction is initiated. The light signal is measured by a photomultiplier as relative light units (RLU) and is proportional to the concentration of CRP present in the calibrators, controls or samples. The result of the CRP reagent pack is only used to calculate a final LIAISON MeMed BV Score and should not be used individually for diagnosis.
The provided document describes the FDA clearance (K213936) for the DiaSorin LIAISON® MeMed BV® assay, which aids in differentiating bacterial from viral infections. Here's a breakdown of the acceptance criteria and study details:
1. Table of Acceptance Criteria and Reported Device Performance
The document primarily focuses on demonstrating substantial equivalence to a predicate device rather than explicitly listing predefined acceptance criteria with numerical targets. However, the performance data presented implies a set of internal acceptance criteria related to statistical significance, agreement with expert adjudication, and reproducibility.
Given the information provided, here's a table summarizing the reported device performance, with implicit acceptance criteria derived from the study's conclusions:
| Performance Metric | Implicit Acceptance Criteria (based on stated conclusions) | Reported Device Performance (LIAISON MeMed BV) |
|---|---|---|
| Clinical Agreement (Primary Endpoint) | Significant trend between SCORE and likelihood of bacterial infection; high percentage of patients in outer bins. | Significant trend demonstrated between LIAISON MeMed BV SCORE and increasing likelihood of bacterial infections across SCORE bins. High percentage of patients found in outer bins (Bin 1 and 5). |
| Likelihood Ratio for Bacterial Basis (Bin 5: High Bacterial) | High Likelihood Ratio indicating strong association with bacterial infection. | 13.00 (7.09-25.83) |
| Likelihood Ratio for Bacterial Basis (Bin 1: Viral) | Low Likelihood Ratio indicating strong association with viral/non-infection. | 0.043 (0.002-0.180) |
| Clinical Agreement (Secondary Endpoint) | Significant trend between SCORE and likelihood of bacterial infection; high percentage of patients in outer bins. | Significant trend demonstrated between LIAISON MeMed BV SCORE and increasing likelihood of bacterial infections across SCORE bins. High percentage of patients found in outer bins (Bin 1 and 5). |
| Likelihood Ratio for Bacterial Basis (Bin 5: High Bacterial) | High Likelihood Ratio. | 52.97 (19.90-214.87) |
| Likelihood Ratio for Bacterial Basis (Bin 1: Viral) | Low Likelihood Ratio. | 0.051 (0.003-0.214) |
| Method Correlation (Primary Endpoint) | High overall agreement and high agreement in outer bins with predicate device. | Overall Agreement: 79.3% (95% CI: 74.2% - 83.6%). Bin 1: 91.8%; Bin 5: 96.7%. |
| Method Correlation (Secondary Endpoint) | High overall agreement and high agreement in outer bins with predicate device. | Overall Agreement: 79.0% (95% CI: 73.6% - 83.5%). Bin 1: 92.2%; Bin 5: 100%. |
| Reproducibility (SCORE) | Acceptable coefficient of variation (CV) across laboratories and within-laboratory. | Reproducibility CV for Score: KC1 (2.24): 0.688 (N/A); KC2 (98.3): 0.491 (N/A); MMBV-PREC3 (55.0): 2.765 (N/A); MMBV-PREC4 (7.84): 1.072 (N/A). |
| Matrix Equivalence (Fresh vs. Frozen Serum) | Strong correlation (slope ~1, intercept ~0, high R-squared) between fresh and frozen samples. | SCORE: Slope 1.00, Intercept 0.00, R-squared 0.9843, R 0.992. |
| Limit of Blank (LoB) | Quantifiable low limit. | CRP: 0.024 mg/L; IP-10: 0.578 pg/mL; TRAIL: 5.33 pg/mL. |
| Limit of Detection (LoD) | Quantifiable low limit. | CRP: 0.067 mg/L; IP-10: 4.31 pg/mL; TRAIL: 7.03 pg/mL. |
| Limit of Quantitation (LoQ) | Quantifiable low limit. | CRP: 1.0 mg/L; IP-10: 100 pg/mL; TRAIL: 15.0 pg/mL. |
| Cross-Reactivity | No significant cross-reactivity with specified substances. | Testing performed; implies no significant cross-reactivity observed (conclusion not explicitly stated but implied by study inclusion). |
| Interfering Substances | No interference observed for specified substances. | "No interference was observed for substances." |
2. Sample Sizes Used for the Test Set and Data Provenance
- Clinical Agreement Test Set: 285 serum samples.
- Provenance: Collected at hospital admission, Emergency Department, and Urgent Care Centers. Patients ranged in age from 5 months to 92 years. The origin country is not explicitly stated, but the mention of "21 international experts" suggests a multi-national or at least internationally adjudicated dataset. The study is retrospective in the sense that samples were likely collected before the adjudication process and testing with the device.
- Method Correlation Test Set:
- Primary Endpoint analysis: 285 clinical samples (the same as the clinical agreement test set).
- Secondary Endpoint analysis: 257 clinical samples (28 of the 285 were excluded).
- Expected Values Test Set: 150 serum samples from apparently healthy asymptomatic adults.
- Provenance: Collected in the Southwestern U.S.
- Reproducibility Study Test Set: 4 serum samples (1 normal, 1 viral, 1 bacterial, 1 equivocal) plus kit controls.
- Cross-Reactivity Study Test Set: Two (2) serum samples (one low, one high SCORE) for each cross-reactant being tested.
- Interfering Substances Study Test Set: Two (2) serum samples (one low, one high SCORE) for each interfering substance being tested.
- Matrix Equivalence Study Test Set: 43 fresh serum samples from individual patients, with 20 spiked for range coverage.
- Limit of Blank, Detection, Quantitation Test Set: Varied based on particular limit, ranging from 4-8 serum/spiked matrix samples for LoD/LoQ studies and 5 calibrator matrix samples for LoB.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Number of Experts: A pool of 21 international experts.
- Qualifications of Experts: Clinicians with at least 7 years of relevant clinical experience. Each panel comprised at least three experts.
4. Adjudication Method for the Test Set
- Method: Expert adjudication.
- Process: Panelists for each subject adjudication were drawn from the pool of 21 international experts. Each panel comprised at least three experts who independently adjudicated the etiologic label for each patient. The etiologic label was determined as bacterial, viral, or non-infectious. The adjudication was based on anonymized patient data. Critically, the adjudicators were blinded to the MeMed BV result (for the primary endpoint) and to CRT and PCT results (for the primary endpoint). For the secondary endpoint, adjudicators were un-blinded to PCT and CRP results.
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 document describes the analytical and clinical performance of an in vitro diagnostic assay (a laboratory test that measures protein levels and computes a score), not an AI-assisted diagnostic tool that human readers interpret. Therefore, an MRMC comparative effectiveness study involving human readers assisting with AI is not applicable and was not performed. The device itself is the "AI" (computational algorithm) that processes biomarker data.
6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done
- Yes, the performance presented for the "LIAISON MeMed BV" assay is a standalone performance of the device (assay and its integrated computational scoring). The "SCORE" is generated by the device's algorithm based on the measured protein levels (TRAIL, IP-10, and CRP), without a human in the loop for the scoring itself. The clinical utility is then evaluated by comparing this score to expert adjudication.
7. The Type of Ground Truth Used
- Type of Ground Truth: Expert consensus (physician expert adjudication). Specifically, physicians were forced to make a bacterial, viral, or non-infectious diagnosis.
8. The Sample Size for the Training Set
- The document does not specify the sample size used for training the algorithm (the "SCORE" computation). This document focuses on the validation of the device for FDA clearance. Typically, details of the training dataset are considered proprietary or part of the algorithm development process prior to clinical validation.
9. How the Ground Truth for the Training Set was Established
- Since the training set size and details are not provided, information on how its ground truth was established is also not available in this document. It is typical for such algorithms to be trained on large, well-characterized datasets, often with similar expert-adjudicated ground truth, but these details are not part of the premarket notification summary.
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(215 days)
The MeMed BV™ test is an automated semi-quantitative immunoassay that measures three non-microbial (host) proteins (TRAIL, IP-10, and CRP) in adult and pediatric serum samples and is intended for use in conjunction with clinical assessments and other laboratory findings as an aid to differentiate bacterial from viral infection. MeMed BV™ is indicated for use in patients presenting to the emergency department or urgent care center and with samples collected at hospital admission from patients with suspected acute bacterial or viral infection, who have had symptoms for less than seven days. The MeMed BV™ test generates a numeric score that falls within discrete interpretation bins based on the increasing likelihood of bacterial infection.
The MeMed BV™ ("BV test" or the "test") is an In-Vitro-Diagnostic device that measures in parallel the blood concentrations of TRAIL, IP-10 and CRP. The test consists of an automated analyzer with built-in hardware and software that conduct chemiluminescence-based analyte measurements of patient serum samples and their computational integration (MeMed Key™), and a disposable cartridge that contains the reagents and controls needed to detect the analytes of interest (MeMed BV™ cartridge). The test generates an answer to each sample, with a test run time of approximately 15 minutes.
The MeMed BV™ test is an automated semi-quantitative immunoassay that measures three non-microbial (host) proteins (TRAIL, IP-10, and CRP) in adult and pediatric serum samples. It's intended for use in conjunction with clinical assessments and other laboratory findings to differentiate bacterial from viral infections in patients with suspected acute bacterial or viral infection, who have had symptoms for less than seven days, and are presenting to the emergency department or urgent care center or at hospital admission. The test generates a numeric score that falls within discrete interpretation bins based on the increasing likelihood of bacterial infection.
Here's a breakdown of the acceptance criteria and the study that proves the device meets them:
1. A table of acceptance criteria and the reported device performance:
The provided document details various analytical performance criteria and associated results. The primary clinical study acceptance criteria are related to the statistical significance of the trend and likelihood ratios.
| Acceptance Criteria Category | Specific Acceptance Criterion | Reported Device Performance |
|---|---|---|
| Analytical Performance | ||
| Limit of Quantitation (LoQ) | Total Error (TE) for TRAIL < 30%, IP-10 < 40%, CRP < 30%. | All tested samples passed the acceptance criteria for TE. Formal LLoQ established at TRAIL - 15 pg/mL, CRP - 1 mg/mL, IP-10 - 100 pg/mL. |
| Reproducibility/Precision (Measurands) | CV ≤ 15% for TRAIL, IP-10, and CRP (excluding healthy specimens for IP-10 and CRP where concentrations are below LoQ). | All measurands' CVs were within the acceptance criteria across repeatability, intermediate precision, and reproducibility studies (e.g., TRAIL CVs ranged from 6.6% to 12.7%, IP-10 CVs from 4.0% to 6.2%, CRP CVs from 4.9% to 11.6%). |
| Reproducibility/Precision (MeMed BV Score) | SD < 12.5 score units. | All scores' SDs were within the acceptance criteria (Repeatability SDs: 0.3-7.5; Intermediate Precision SDs: 0.3-7.7; Reproducibility SDs: 0.4-9.4). |
| Lot-to-Lot Reproducibility (Measurands) | CV ≤ 15% for TRAIL, IP-10, and CRP (excluding healthy specimens for IP-10 and CRP). | All measurands' CVs for between-lots analysis were within the acceptance criteria (e.g., TRAIL CVs 0.0-1.6%, IP-10 CVs 0.0-7.3%, CRP CVs 0.0-1.2%). |
| Lot-to-Lot Reproducibility (MeMed BV Score) | SD < 12.5 score units. | All scores' SDs for between-lots analysis were within the acceptance criteria (all 0.0). |
| Linearity | Measurement bias due to non-linearity < 10% or 10mg/L for CRP, 10% or 10 pg/mL for TRAIL, and 10% or 50 pg/mL for IP-10. | The degree of non-linearity for CRP and IP-10 (Lot 1 and Lot 2) was within the acceptance criteria. |
| Hook Effect | Responses obtained for concentrations up to Level 4 were no less than the response obtained for ULoQ. | No hook effect was observed for TRAIL up to 1,000 pg/mL, IP-10 up to 10,000 pg/mL, and CRP up to 500 mg/L. |
| Carry Over | Difference between average scores of high/low sequence no more than 12.5 score units. | Maximal difference in score was 1 score unit, demonstrating no carry-over. |
| Interference/Cross Reactivity | Bias between spiked and non-spiked score results was ± 12.5 score units. | The 95% confidence interval for the bias was within +/-12.5 score units for all tested interferents and cross-reactants. |
| HAMA Interference | TRAIL, CRP, and IP10 concentrations, when run on clinical serum sample mixed with HAMA positive sample, shall measure concentrations within +/- 10% compared to their nominal concentration. | For both HAMA samples, the recovery of TRAIL, IP-10, and CRP was within +/- 10%. |
| In-Use Stability | Mean values, regression lines, confidence intervals, and significance level of the difference of the slope from 0 were examined. | Allowable incubation time at room temperature before centrifugation was established at 120 minutes. |
| Freeze-Thaw Stability | All scores within the 95% confidence interval are within the same or adjacent score categories and do not result in a move between non-adjacent scores. | Frozen and fresh samples demonstrated score results corresponding to the same or adjacent scores within the 95% confidence interval, thus demonstrating equivalency. |
| Clinical Performance | ||
| Primary Objective Cohort: Cochran-Armitage (CA) Test | Significant trend in increasing probability of bacterial infection with higher MeMed BV™ score (p < 0.05). | p < 0.0001; trend in increasing probability of bacterial infection was demonstrated. |
| Primary Objective Cohort: Likelihood Ratio (LR) for bins | 95% CI of the LR for some bins (Bins 1,2,4,5) excluded 1. | 95% CI for Bins 1 (0.1-0.2), 2 (0.3-0.6), 4 (2.1-3.1), and 5 (6.3-10.5) excluded 1. |
| Secondary Objective Cohort: Cochran-Armitage (CA) Test | Significant trend in increasing probability of bacterial infection with higher MeMed BV™ score (p < 0.05). | p < 0.0001; trend in increasing probability of bacterial infection was demonstrated. |
| Secondary Objective Cohort: Likelihood Ratio (LR) for bins | 95% CI of the LR for some bins (Bins 1,2,4,5) excluded 1. | 95% CI for Bins 1 (0.0-0.1), 2 (0.0-0.3), 4 (1.5-4.0), and 5 (16.6-37.8) excluded 1. |
2. Sample sizes used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective):
- Clinical Study Test Set Sample Size:
- Primary Objective Cohort: 1016 infectious subjects. This included 476 prospectively recruited adult and pediatric patients and 540 archived cases.
- Secondary Objective Cohort: 872 subjects (after removing 144 indeterminate cases from the primary cohort).
- Prospectively recruited patients (subgroup analysis): 476 patients.
- Archived cases (subgroup analysis): 540 cases.
- Data Provenance: The study was a prospective, multicenter, observational, and blinded study. Patients were recruited from 11 medical centers (9 in the US and 2 in Israel). Therefore, the data originates from both the United States and Israel, and it includes both prospective and retrospective (archived cases) data.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
The document states that the ground truth for the clinical study was established using an "expert adjudication comparator method." It also mentions "experts blinded to C-reactive protein (CRP) and procalcitonin (PCT) values" for the primary objective, and "experts given CRP and PCT values" for the secondary objective.
The number of experts and their specific qualifications (e.g., "radiologist with 10 years of experience") are not explicitly detailed in the provided text.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:
The term "expert adjudication comparator method (forced diagnosis for indeterminate cases)" is used for the primary objective, and "expert adjudication comparator method (indeterminate cases removed from analysis)" for the secondary objective.
The specific method of adjudication (e.g., if multiple experts made independent decisions and how discrepancies were resolved like "2+1" or "3+1") is not explicitly stated in the provided text.
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:
A multi-reader multi-case (MRMC) comparative effectiveness study focusing on human readers' improvement with vs. without AI assistance was not described in the provided text. The clinical study assessed the standalone diagnostic performance of the MeMed BV™ test itself (algorithm only, as an aid to differentiate infection), not its impact on human reader performance.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
Yes, a standalone performance study was done. The "Apollo Clinical Study" evaluated the diagnostic performance of the MeMed BV™ test (an automated immunoassay with computational integration) in differentiating bacterial from viral infection. The results tabulated in Tables 17 and 18, and Figures 1 and 2, demonstrate the performance of the device's algorithmic output (numeric score and interpretation bins) against the expert-adjudicated reference standard, without human-in-the-loop interaction being part of the primary outcome measurement itself.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc):
The primary type of ground truth used for the clinical study was expert adjudication. For the primary objective cohort, it involved a "forced diagnosis for indeterminate cases" where experts were blinded to CRP and PCT values. For the secondary objective cohort, expert adjudication was used, but indeterminate cases were removed from the analysis, and experts were given CRP and PCT values.
8. The sample size for the training set:
The provided document does not specify the sample size used for the training set for the MeMed BV™ test's algorithm. The document focuses on the test set used for analytical and clinical validation.
9. How the ground truth for the training set was established:
The document does not provide information on how the ground truth for any potential training set was established. It only details the ground truth establishment method for the clinical study's test set.
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