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VIDAS® C. difficile GDH (GDH) is an automated test based on the Enzyme Linked Fluorescent Assay technique (ELFA), for use on the VIDAS family instruments. The VIDAS C. difficile GDH (glutamate dehydrogenase) assay is a qualitative test that detects the C. difficile antigen, glutamate dehydrogenase, as a screen for the presence of C. difficile in fecal specimens from persons suspected of having C. difficile infection (CDI). The test does not distinguish toxigenic from non-toxigenic strains of C. difficile. With the use of additional tests that detect C. difficile toxins, the test is to be used as an aid in the diagnosis of C. difficile infection. As with other C. difficile tests, results should be considered in conjunction with the patient history.

The VIDAS® C. difficile GDH assay principle combines a two-step enzyme immunoassay sandwich method with a final fluorescent detection (ELFA). The Solid Phase Receptacle (SPR®) serves as the solid phase as well as the pipetting device. Reagents for the assay are ready-to-use and are pre-dispensed in the sealed reagent strips. All of the assay steps are performed automatically by the instrument. The reaction medium is cycled in and out of the SPR several times. Each step is followed by a wash cycle which eliminates unbound components. Specific binding of GDH present in the sample with mouse monoclonal anti-GDH antibody coated on the interior of the SPR. Binding between GDH and mouse monoclonal anti-GDH antibody conjugated with alkaline phosphatase (ALP). Detection: alkaline phosphatase catalyzes the hydrolysis of the substrate (4-Methylumbellifery! phosphate) into a fluorescent product (4-Methy-umbelliferone) the fluorescence of which is measured at 450 nm. The intensity of the fluorescence increases according to the quantity of GDH in the sample. When the VIDAS C. difficile GDH test is completed, the results are analyzed automatically by the instrument, a test value is generated, and a result is printed for each sample.

The provided document describes the VIDAS® C. difficile GDH assay, intended for the detection of C. difficile antigen glutamate dehydrogenase in fecal specimens.

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 document does not explicitly state pre-defined acceptance criteria for clinical performance (sensitivity and specificity) in a pass/fail format. However, it presents the results of clinical studies against two different reference methods. The "Performance" rows in the tables below can be considered the reported device performance.

Against CCFA Bacterial Culture (Reference Standard)

Against C. difficile Chromogenic Media Bacterial Culture (Reference Standard)

Against a Commercially Available C. difficile GDH Assay (Comparison Study)

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: 1904 stool samples (1891 prospective and 13 retrospective).
• Data Provenance: The samples were collected from patients suspected of having C. difficile infection (CDI) at three sites across the USA and Europe.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

The document does not specify the exact number of experts involved in establishing the ground truth or their specific qualifications (e.g., radiologist with X years of experience). The ground truth was established by bacterial culture tests (CCFA and C. difficile chromogenic media) performed "according to the instructions for use." This implies standard laboratory practices would have been followed, likely by trained laboratory personnel.

4. Adjudication Method for the Test Set

The document does not mention any adjudication method for resolving discordant results between the device and the ground truth. It presents the raw comparison data against the reference methods.

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 study is for a diagnostic assay, and the studies described are evaluations of the assay's performance against reference methods and another commercially available assay.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

Yes, a standalone performance study was done. The VIDAS® C. difficile GDH assay is an automated test, and the reported clinical sensitivity, specificity, and agreement data reflect the performance of the algorithm only (the automated instrument) without additional human interpretation or intervention in the diagnostic decision once the test is run. The instrument generates a test value and prints a result for each sample automatically.

7. The Type of Ground Truth Used

The primary ground truth used for the clinical performance evaluation was bacterial culture:

• CCFA bacterial culture test
• C. difficile chromogenic medium bacterial culture test

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" or its size. This is common for diagnostic assays where the development process typically involves internal optimization and validation, and then external clinical validation (the "test set" described) against a gold standard. The clinical study described served as the validation (test) set.

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

As no specific training set is outlined in the document, there's no information on how its ground truth might have been established. However, for diagnostic assays, internal development and optimization would generally rely on well-characterized samples with confirmed positive and negative status, likely through similar gold standard methods like bacterial culture, to establish parameters like cut-off values.

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ImmunoCard C. difficile GDH is a rapid qualitative enzyme immunoassay screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from persons suspected of having C. difficile infection (CDI). This test does not distinguish between toxigenic and non-toxigenic strains of C. difficile. Samples from patients that produce positive results with this test must be further tested with an assay designed to detect toxigenic C. difficile strains and assist with the diagnosis of CDI.

ImmunoCord C. difficile GDH is a rapid qualitative enzyme immunoassay screening test to detect Clostridium difficile antigen, glutamate dehydrogenase (GDH), in fecal specimens from persons suspected of having C. difficile infection. The assay consists of ImmunoCard C. difficile GDH Test Cards containing immobilized polyclonal anti-C. difficile GDH antibodies, ImmunoCard C. difficile GDH Positive Control, ImmunoCard C. difficile GDH Sample Diluent/Negative Control, ImmunoCard C. difficile GDH Enzyme Conjugate, ImmunoCard Wash Buffer I, and ImmunoCard Substrate I.

Here's an analysis of the ImmunoCard C. difficile GDH device based on the provided document, addressing the requested information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for sensitivity and specificity are not explicitly stated as distinct "acceptance criteria" beyond the presented performance metrics. However, based on the desire to demonstrate substantial equivalence, the reported performance of the ImmunoCard C. difficile GDH is compared to bacterial culture as the reference.

(Note: The document implies these performance levels are the acceptance criteria for regulatory submission as they are the key clinical performance results presented for review.)

2. Sample size used for the test set and the data provenance

• Sample Size (Clinical Test Set): 975 qualified patient samples.
• Data Provenance:
  • Country of Origin: United States (Midwestern, Southwestern, and Western regions).
  • Retrospective or Prospective: Prospectively collected.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts

The document does not explicitly state the number or qualifications of "experts" used to establish the ground truth. The ground truth was established by bacterial C. difficile culture, which is a laboratory-based method. The performance of the culture itself would typically be overseen by trained laboratory personnel, but no specific "experts" for truth adjudication are mentioned outside of the methodology.

4. Adjudication method for the test set

There is no mention of an adjudication method like 2+1 or 3+1 for the clinical test set. The ImmunoCard C. difficile GDH assay results were directly compared to the results of bacterial C. difficile culture.

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 was not done. This is not an AI-based device, but rather a rapid qualitative enzyme immunoassay (EIA) intended for screening.

6. If a standalone (i.e. algorithm only without human-in-the loop performance) was done

This question is not applicable in the context of this device. The ImmunoCard C. difficile GDH is itself a "standalone" diagnostic test (an EIA) that produces a visual read (positive/negative) which is then interpreted by a human. There is no separate "algorithm only" performance reported, as the human interpretation of the visual reaction is an inherent part of the device's function.

7. The type of ground truth used

The type of ground truth used for the clinical performance comparison was bacterial C. difficile culture.

8. The sample size for the training set

The document does not explicitly mention a "training set" in the context of machine learning or AI. This is a traditional immunoassay. However, if we interpret "training set" as the samples used for initial development and optimization of the assay prior to clinical validation, that information is not detailed here. The analytical studies (sensitivity, interference, cross-reactivity, strain reactivity) involved various spiked and natural samples, but these are not referred to as a "training set" in the sense of a machine learning model.

9. How the ground truth for the training set was established

As there is no distinct "training set" described in the machine learning sense, the establishment of its ground truth is not applicable. For the analytical studies (e.g., sensitivity, cross-reactivity), the ground truth was established by:

• Known concentrations of C. difficile GDH antigen (for analytical sensitivity/limit of detection).
• Known presence or absence of specific microorganisms/substances (for interference and cross-reactivity studies).
• Confirmed C. difficile stock cultures (for strain reactivity).

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Premier C. difficile GDH is a qualitative enzyme immunoassay screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from symptomatic persons suspected of having C. difficile infection (CDI). This test does not distinguish between toxigenic strains of C. difficile. Samples from symptomatic patients that produce positive results with this test must be further tested with an assay designed to detect toxigenic C. difficile strains and assist with the diagnosis of CDI.

Premier C. difficile GDH is a qualitative enzyme immunoassay screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from symptomatic persons suspected of having C. difficile infection (CDI). The assay consists of Premier C. difficile GDH Microwells coated with polyclonal antibodies specific to C. difficile GDH, Premier C. difficile GDH Enzyme Conjugate, Premier 20X Wash Buffer II, Premier Substrate I, Premier Stop Solution I, Premier C. difficile GDH Sample Diluent/Negative Control, and Premier C. difficile GDH Positive Control.

Here's a summary of the acceptance criteria and study findings for the Premier C. difficile GDH assay, based on the provided text:

Acceptance Criteria and Device Performance

The document implicitly defines acceptance criteria through the reported performance characteristics. The primary measure of clinical performance is the comparison to bacterial C. difficile culture.

Table 1: Acceptance Criteria and Reported Device Performance (Clinical Study)

Study Information

1. Sample sizes used for the test set and the data provenance:

   • Test Set Sample Size: 733 qualified patient samples.
   • Data Provenance: The data was collected prospectively (clinical trials conducted from November 2011) from independent clinical test sites located in the Midwestern and Southwestern regions of the United States. Gender and age ranges were reported (22 days to 99 years).

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

   • The document states that the performance characteristics were determined by comparison to bacterial C. difficile culture. It does not mention the use of human experts to establish ground truth for the clinical test set; rather, the gold standard for diagnosis was a laboratory method (bacterial culture).

3. Adjudication method for the test set:

   • Since the ground truth was established by bacterial C. difficile culture, an expert adjudication method (like 2+1, 3+1) was not described or necessary. The comparison was directly against the culture results.

4. 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:

   • No MRMC comparative effectiveness study was done. This device is an Enzyme Immunoassay (ELISA) kit, which is a laboratory test where results are read spectrophotometrically or visually from a microplate, not an imaging device requiring human interpretation of complex visual data. Therefore, the concept of "human readers improve with AI vs without AI assistance" is not applicable.

5. If a standalone (i.e. algorithm only without human-in-the loop performance) was done:

   • Yes, the clinical performance described (sensitivity, specificity, correlation) represents the standalone performance of the Premier C. difficile GDH assay. It is an "algorithm only" in the sense that it is a biochemical assay designed to yield a direct result (positive/negative) based on antigen detection, without human interpretation influencing the diagnostic outcome beyond standard laboratory procedures (e.g., pipetting, reading the spectrophotometer).

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • The ground truth used for the clinical performance evaluation was bacterial C. difficile culture.

7. The sample size for the training set:

   • The document does not explicitly state a "training set" in the context of machine learning or AI models. For an ELISA kit, development typically involves analytical studies (sensitivity, specificity, interference, cross-reactivity, strain reactivity) and then clinical validation. The "analytical sensitivity" study used 45 replicates for each measurand. The "reproducibility" panels involved blind-coded samples tested multiple times. These studies contribute to the device's development and validation but are not a "training set" in the common AI sense.

8. How the ground truth for the training set was established:

   • Again, the concept of a "training set" in the AI sense is not directly applicable. For the analytical studies, the "ground truth" (e.g., known concentration of C. difficile GDH antigen, presence/absence of interfering substances, known microorganisms) was established through controlled laboratory spiking and preparation of contrived samples. For the broader validation, bacterial C. difficile culture served as the reference standard.

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The C. DIFF QUIK CHEK™ test is a rapid membrane enzyme immunoassay for use as a screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from persons suspected of having C. difficile disease. The test does not distinguish toxigenic from nontoxigenic strains of C. difficile. With the use of additional tests that detect C. difficile toxins, the test is to be used as an aid in the diagnosis of C. difficile disease. As with other C. difficile tests, results should be considered in conjunction with the patient history. FOR IN VITRO DIAGNOSTIC USE.

The C. DIFF QUIK CHEK™ test uses antibodies specific for glutamate dehydrogenase (GDH) of C. difficile. The device contains a Reaction Window with two lines of immobilized antibodies. The test line ("T") contains antibodies against C. difficile GDH. The other, representing a control line ("C"), contains anti-IgG antibodies. The Conjugate consists of antibody to GDH coupled to horseradish peroxidase. To perform the test, the fecal specimen is diluted with Diluent, and Conjugate is added to the diluted sample. The diluted sample conjugate mixture is added to the Sample Well and the device is allowed to incubate at room temperature for 15 minutes. During the incubation, any GDH in the sample binds to antibodyperoxidase conjugate. The antigen-antibody complexes migrate through a filter pad to a membrane where they are captured by the immobilized anti-GDH antibody in the line. The Reaction Window is subsequently washed with Wash Buffer, followed by the addition of Substrate. After up to a 10-minute incubation, the "T" reaction is examined visually for the appearance of a blue line indicates a positive test. A positive "C" reaction, indicated by a blue line, confirms that sample and all reagents were added in proper sequence and volume, that reagents were active at the time of performing the assay, and that proper sample migration occurred.

Here's a summary of the acceptance criteria and the study that proves the device meets them, based on the provided text:

Device: C. DIFF QUIK CHEK™ test

Intended Use: A rapid membrane enzyme immunoassay for use as a screening test to detect Clostridium difficile antigen, glutamate dehydrogenase, in fecal specimens from persons suspected of having C. difficile disease. The test does not distinguish toxigenic from nontoxigenic strains of C. difficile. With the use of additional tests that detect C. difficile toxins, the test is to be used as an aid in the diagnosis of C. difficile disease. Results should be considered in conjunction with the patient history.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the document. However, the study aims to demonstrate substantial equivalence to previously cleared devices and clinical correlation. Based on the "Clinical Performance Comparing C. DIFF QUIK CHEK™ Test to Presumptive Bacterial Culture" table and the "Clinical Performance of C. DIFF QUIK CHEK™ Test versus Bacterial Culture Assay after Resolution by another GDH Test" table, the implied acceptance range would be within the 95% Confidence Limits of the reported performance metrics.

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size: 979 fecal specimens.
• Data Provenance: The document states that "Results from 3 studies are included in the summary," and the protocols are in Appendix A and D. It does not specify the country of origin of the data or whether it was retrospective or prospective.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts

The document does not explicitly state the number or qualifications of experts used to establish initial ground truth. The primary comparator was "Presumptive Bacterial Culture."

4. Adjudication Method for the Test Set

The document describes an adjudication method for discrepant samples:

• "The discrepant samples generated from the C. DIFF QUIK CHEK™ test and the presumptive bacterial culture assay were resolved using a PCR assay, an ELISA for the antigen, or a membrane test for the antigen, as described in the individual studies."
• This indicates a "discrepant analysis" approach, where discrepancies between the index test (C. DIFF QUIK CHEK) and the initial comparator (presumptive bacterial culture) were sent for re-evaluation using one or more additional, often more sensitive or specific, methods (PCR, ELISA, membrane test).

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

No, a multi-reader, multi-case (MRMC) comparative effectiveness study was not done. This device is an in-vitro diagnostic test (a rapid membrane enzyme immunoassay) and not an AI-assisted diagnostic tool designed to aid human readers in interpreting images or other complex data. Therefore, the concept of human readers improving with AI assistance does not apply.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

Yes, a standalone performance study was done. The C. DIFF QUIK CHEK™ test is presented as a standalone diagnostic device, where the visual interpretation of a distinct blue line (or lack thereof) is the final output. The performance metrics (sensitivity, specificity, etc.) presented are for the device operating independently.

7. The Type of Ground Truth Used

The primary initial ground truth was presumptive bacterial culture (Clostridium difficile Culture media such as cycloserine cefoxitin fructose agar (CCFA)).

For discrepant results, the refined ground truth was established using consensus or advanced methods including:

• PCR assay
• ELISA for the antigen
• Another membrane test for the antigen

This is a form of resolved gold standard, where a more definitive test is used to resolve disagreements between the index test and the initial comparator.

8. The Sample Size for the Training Set

The document does not provide information regarding a specific "training set" or its sample size. This type of regulatory submission (510(k)) for an in-vitro diagnostic typically focuses on clinical validation of the final device, rather than the developmental or training phases that might involve machine learning algorithms. The development of an immunoassay involves laboratory optimization and verification, but not typically a "training set" in the context of AI.

9. How the Ground Truth for the Training Set was Established

As no specific training set information is provided, how its ground truth was established is not applicable and not described in this document.

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The Triage® C. difficile test is an enzyme immunoassay used for the detection of Clostridium difficile antigen (glutamate dehydrogenase or common antigen) and Toxin A in human fecal specimens. The test will be offered as two singular tests for each protein. This test is used as an aid in the diagnosis of C. difficile associated disease.

The Triage® C. difficile test is an enzyme immunoassay.

The provided document is an FDA 510(k) clearance letter for the Triage® C difficile Panel. It confirms that the device is substantially equivalent to a legally marketed predicate device. However, this document does not contain any information regarding acceptance criteria, study details, or performance data for the device.

Therefore, I cannot provide the requested information based on the given text. The letter only acknowledges the device's clearance for marketing.

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