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Simplexa C. difficile Direct: The Focus Diagnostics Simplexa™ C. difficile Direct assay is intended for use on the Integrated Cycler instrument for the detection of Clostridium difficile toxin B gene (tcdB) present in liquid or unformed stool samples from individuals suspected of C. difficile infection (CDI). This test aids in the diagnosis of illness resulting from CDI. The assay is for professional and prescription use only.

Simplexa C. difficile Positive Control Pack: The Simplexa™ C. difficile Positive Control Pack is intended to be used as a control with the Simplexa™ C. difficile Direct kit. This control is not intended for use with other assays or systems.

The Simplexa™ C. difficile Direct assay system is a real-time PCR system that enables the direct amplification and detection of toxigenic C. difficile DNA from unprocessed liquid or unformed stool specimens that have not undergone nucleic acid extraction. The system consists of the Simplexa™ C. difficile Direct assay, the Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories. In the Simplexa™ C. difficile Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify C. difficile and DNA internal control targets. The assay targets a sequence which is in a well conserved region of C. difficile toxin B gene (todB). A DNA internal control is used to detect PCR failure and/or inhibition

Acceptance Criteria and Device Performance for Simplexa C. difficile Direct

1. Table of Acceptance Criteria and Reported Device Performance

The provided document describes the performance of the Simplexa C. difficile Direct assay in comparison to various gold standards and other NAATs. The acceptance criteria are implicit in the presented tables.

Acceptance Criteria for Simplexa C. difficile Direct (versus Combined Culture + Toxin Assay):

Additional Performance (versus other FDA-cleared NAATs for reference):

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

The primary clinical performance study (method comparison) used 2351 samples prospectively collected.

• Data Provenance: Samples were prospectively collected from five (5) geographically diverse sites in the USA between December 3, 2015, and June 10, 2016.
• Evaluable Samples: 2330 samples were evaluable on Simplexa C. difficile Direct & the Direct Culture method, and 2336 were evaluable on Simplexa C. difficile Direct & the Combination of Direct/Enriched Culture methods.
• Invalid Rate: The initial invalid rate was 0.64% (15/2351), reduced to a final invalid rate of 0.13% (3/2351) after repeat testing.

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" involved in establishing the ground truth for the clinical sample test set. However, the ground truth was based on Direct Culture + Toxin Assay and Combined Culture (Direct & Enriched) + Toxin Assay, with confirmatory testing using FDA cleared nucleic acid amplification test (NAAT) results for discrepant analysis. This implies that the ground truth was established by laboratory methods and not by individual expert interpretation.

4. Adjudication Method for the Test Set

For discrepant samples in the clinical study, discrepant analysis was performed using FDA cleared nucleic acid amplification test (NAAT) results provided by the sites.

• For the "Simplexa C. difficile Direct versus Direct Toxigenic Culture Method" table:
  • 116/163 discrepant Simplexa-positive/Culture-negative samples were positive, and 46/163 were indeterminate for C. difficile Toxin B gene DNA when tested using an FDA cleared molecular test.
  • 8/12 discrepant Simplexa-negative/Culture-positive samples were negative, and 4/12 were positive for C. difficile Toxin B gene DNA when tested using an FDA cleared molecular test.
• For the "Simplexa C. difficile Direct versus Combined Direct and Enriched Toxigenic Culture Methods" table:
  • 59/96 discrepant Simplexa-positive/Culture-negative samples were positive, and 37/96 were negative for C. difficile Toxin B gene DNA when tested using an FDA cleared molecular test.
  • 43/55 discrepant Simplexa-negative/Culture-positive samples were negative for C. difficile Toxin B gene DNA when tested using an FDA cleared molecular test.

This indicates an adjudication process involving a third, independent, FDA-cleared NAAT for resolving discrepancies between the investigational device and the culture methods.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study was not explicitly described in the provided text. The study focuses on the performance of the analytical device rather than human reader interpretation with or without AI assistance.

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

Yes, the studies presented are standalone performance evaluations of the Simplexa C. difficile Direct assay. The assay is an automated real-time PCR system designed for direct detection of C. difficile toxin B gene, meaning its performance is measured independently of human interpretation of its results, although trained lab personnel would operate the instrument.

7. The Type of Ground Truth Used

The ground truth for the clinical performance study was established using:

• Direct Culture + Toxin Assay
• Combined Culture (Direct & Enriched) + Toxin Assay
• FDA cleared molecular tests (NAATs) for discrepant analysis.

This represents a composite reference standard based on microbiological culture techniques and molecular detection for toxigenic C. difficile, with additional molecular confirmation for discordant results.

8. The Sample Size for the Training Set

The document does not specify a separate "training set" sample size. The studies described are performance evaluations of the device, implying that the device's development and internal optimization would have occurred prior to these validation studies. Therefore, information regarding a training set is not provided as this is a diagnostic assay, not a machine learning algorithm that requires a separate training and test set in the same way.

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

As no specific training set is mentioned for the device (which is a molecular diagnostic assay), the method for establishing ground truth for such a set is not applicable or described in this document. The focus is on the analytical and clinical validation of the completed product.

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The Focus Diagnostics Simplexa™ Flu A/B & RSV Direct assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and differentiation of influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Focus Diagnostics' Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the Simplexa™ Flu A/B & RSV Direct kit. This control is not intended for use with other assays or systems.

The Simplexa™ Flu AB & RSV Direct assay system is a real-time RT-PCR system that enables the direct amplification, detection and differentiation of human influenza A (Flu A) virus RNA, human influenza B (Flu B) virus RNA and RSV RNA from unprocessed nasopharyngeal swabs that have not undergone nucleic acid extraction. The system consists of the Simplexa™ Flu A/B & RSV Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories.

In the Simplexa™ Flu A/B & RSV Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Flu A, Flu B, RSV and internal control RNA. The assay provides three results; conserved regions of influenza A viruses (matrix gene), influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to detect RT-PCR failure and/or inhibition.

Here's a summary of the acceptance criteria and the study information for the Simplexa™ Flu A/B & RSV Direct device, based on the provided document:

Acceptance Criteria and Device Performance Study

The purpose of this Special 510(k) (K152408) is to expand the analytical reactivity of the Simplexa™ Flu A/B & RSV Direct assay to include 53 additional strains. Therefore, the primary acceptance criteria for this specific submission relate to the successful detection of these new strains.

1. Table of Acceptance Criteria and Reported Device Performance

The core acceptance criterion for the additional strains is detection by the Simplexa™ Flu A/B & RSV Direct assay. All tested strains were successfully detected.

Note: The document explicitly states: "Fifty-three strains met the established acceptance criteria and passed validation testing. Analytical Reactivity will be expanded to add 53 additional strains." This confirms that the acceptance criteria for these specific strains was successful detection.

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

• Test Set Sample Size: For each of the 53 additional strains, the testing was performed in triplicate. This means a total of 53 strains * 3 replicates = 159 individual tests were performed for this specific analytical reactivity study.
• Data Provenance: The strains were sourced from various locations and historical periods, indicating a focus on analytical validity and strain diversity rather than clinical performance from a specific population or region. Examples include strains like "A/California/4/2009", "A/Massachusetts/15/2013", "A/Japan/305/57", "B/Brisbane/33/2008", and "ATCC-2012-10". The study itself is an analytical study conducted in a lab setting, not a direct clinical study. The document doesn't specify the country of origin where the testing took place, but it's likely a controlled lab environment.

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

This study focuses on analytical reactivity, where the "ground truth" is the presence and identification of a specific viral strain at a known concentration. This type of ground truth does not typically involve expert clinical adjudication. The ground truth (i.e., confirmation of the viral strain and its concentration) would have been established by standard laboratory methods for viral culture, quantification (e.g., TCID50/mL, CEID50/mL, PFU/mL), and characterization, prior to being used in the Simplexa™ assay. The document does not specify the number or qualifications of experts involved in establishing this initial ground truth, as it's a standard process in virology.

4. Adjudication Method for the Test Set

No adjudication method (e.g., 2+1, 3+1) is described, as this is an analytical study evaluating device performance against known quantities of target analytes, not a clinical study requiring human interpretation or consensus for diagnosis. The "result" is the output of the RT-PCR system ("Flu A Detected," "Flu B Detected," "RSV Detected").

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

No MRMC comparative effectiveness study was done for this particular submission. This 510(k) is a "Special 510(k)" to expand analytical reactivity, not to re-evaluate or compare clinical effectiveness with human readers. The clinical performance characteristics were established in a previous submission (K142365).

6. Standalone Performance Study (Algorithm Only Without Human-in-the-Loop)

Yes, a standalone performance study was done for the analytical reactivity. The study evaluated the ability of the Simplexa™ Flu A/B & RSV Direct assay system (algorithm/device only) to detect the specified viral strains. The results presented ("Flu A Detected," "Flu B Detected," "RSV Detected") are direct outputs from the device, with no human intervention in the detection process itself.

7. Type of Ground Truth Used

The ground truth used for this analytical reactivity study was based on known quantified viral material. This means:

• Viral Culture/Quantification: Viral samples were quantified using methods like TCID50/mL (Tissue Culture Infectious Dose 50%), CEID50/mL (Chicken Embryo Infectious Dose 50%), PFU/mL (Plaque Forming Units/mL), or using purified RNA at known concentrations (e.g., ng/µL, IU/mL).
• Strain Identification: The specific identity and subtype of each viral strain were confirmed through standard virological methods.
• These known viral materials were then spiked into a negative swab matrix to simulate clinical samples for testing.

8. Sample Size for the Training Set

The document does not provide details about the training set sample size. This submission (K152408) is an expansion of analytical reactivity and refers to the predicate device K142365 for most other performance characteristics, including clinical studies. RT-PCR assays typically do not have a "training set" in the machine learning sense, but rather a development and validation process during which assay parameters are optimized and locked.

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

Similar to point 8, the document does not specifically detail how a "training set ground truth" was established, as it's not a machine learning algorithm in the typical sense that would require a distinct training phase with labeled data in the way, for example, an image recognition AI would. The development of an RT-PCR assay involves optimization and validation studies using characterized viral isolates and clinical samples, where the "ground truth" for these samples is derived from:

• Reference Methods: Such as viral culture, sequencing, or other FDA-cleared assays.
• Expert Consensus: For clinical samples, expert microbiologists or virologists would confirm the presence/absence of target viruses using gold standard methods.

The current document focuses singularly on the analytical reactivity towards an expanded panel of viral strains, relying on the already established methodologies from the predicate device (K142365) for other aspects of performance.

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The Focus Diagnostics Simplexa™ Group A Strep Direct assay is intended for use on the 3M Integrated Cycler for the in vitro qualitative detection of Group A Streptococcus (GAS) from throat swabs collected from human patients with signs and symptoms of pharyngitis, such as sore throat. This test is intended for use as an aid in the diagnosis of GAS infection. The assay is intended for use in hospital, reference, or state laboratory settings. The device is not intended for point-of-care use.

The Simplexa™ Group A Strep Direct assay system is a real-time PCR system that enables the direct amplification and qualitative detection of Group A Strep bacterial DNA from throat swabs that have not undergone a nucleic acid extraction. The system consists of the Simplexa™ Group A Strep Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc (DAD) and associated accessories.

In the Simplexa™ Group A Strep Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Group A Strep bacterial DNA and the Internal Control (DNA IC). The assay targets a conserved region of Group A Strep (pyroqenic exotoxin B gene) to identify this bacteria in the specimen. The DNA IC is used to detect PCR failure and/or inhibition.

Here is a summary of the acceptance criteria and study information for the Simplexa™ Group A Strep Direct device, based on the provided text:

Acceptance Criteria and Device Performance for Simplexa™ Group A Strep Direct

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly state pre-defined acceptance criteria for the clinical study's sensitivity and specificity. However, the performance characteristics of the device and its predicate device are compared. For the purpose of this response, we will consider the reported "Performance Characteristics" of the predicate device as a benchmark or implicit acceptance criteria, though the device has slightly lower specificity than the predicate.

Note: The device's sensitivity (97.4%) is numerically higher than the predicate's (96.5%), and its specificity (95.2%) is numerically lower than the predicate's (98.0%). The FDA's substantial equivalence determination implies these results were acceptable.

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

• Sample Size for Test Set: 1352 evaluable samples.
• Data Provenance: Prospectively collected from four geographically diverse sites. The country of origin is not explicitly stated but can be inferred to be the USA given the FDA submission document.

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

The document does not mention the use of "experts" in the traditional sense (e.g., radiologists) for establishing ground truth. Instead, for the clinical prospective study, the comparator culture method was used as the primary reference for ground truth, and discrepant results were further analyzed.

4. Adjudication Method for the Test Set

The primary comparison was against a "comparator culture method" performed at one central laboratory.
For discrepant analysis, a "validated bidirectional sequencing assay" was performed.

• 46 out of 57 samples where Simplexa™ was Positive and Culture was Not Detected were confirmed as Group A Strep Positive by sequencing.
• 2 out of 4 samples where Simplexa™ was Not Detected and Culture was Detected were confirmed as Group A Strep Positive by sequencing.

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

No, a multi-reader multi-case (MRMC) comparative effectiveness study was not performed. This device is a molecular diagnostic assay (PCR-based system) for the qualitative detection of Group A Streptococcus, not an imaging device requiring human reader interpretation. Therefore, the concept of improving human readers with AI assistance is not applicable here.

6. Standalone Performance Study

Yes, a standalone performance study (algorithm only without human-in-the-loop performance) was performed. The entire clinical prospective study and analytical studies evaluate the device's performance independently. The device's results are compared directly against a culture method and a sequencing assay, not against human interpretation of the device's output.

7. Type of Ground Truth Used

• Primary Ground Truth: Comparator culture method.
• Confirmatory Ground Truth for Discrepancies: Validated bidirectional sequencing assay.

8. Sample Size for the Training Set

The document describes the performance of the device and does not explicitly mention a "training set" in the context of machine learning. The studies described are validation studies (e.g., Limit of Detection, Analytical Reactivity, Cross Reactivity, Interference, Clinical Prospective Study) that assess the device's performance characteristics. If the device's internal algorithms underwent a "training" phase during its development, the details are not provided in this regulatory summary.

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

As no specific "training set" is mentioned for an algorithm, the method for establishing its ground truth is not provided. The document focuses on the validation of the finalized device.

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The Focus Diagnostics' STRATIFY JCV® DxSelect™ assay is intended for the qualitative detection of antibodies to JC virus in human serum or plasma. The assay is intended for use in conjunction with other clinical data, in multiple sclerosis patients receiving or considering natalizumab therapy, as an aid in risk stratification for progressive multifocal leukoencephalopathy development. The assay is for professional use only.

The assay is not intended for donor screening. The performance of this assay has not been established for use in other immunocompromised patient populations or patients with different disease conditions or undergoing other treatments or in neonates and pediatric patient populations.

The Focus Diagnostics' STRATIFY JCV® DxSelect™ test is an ELISA assay. JC virus-like particles (VLP) are pre-coated onto 96-well microiter plates. Diluted serum or plasma specimens and controls are incubated in the wells to allow JCV-specific antibodies present in the specimens to react with the JC VLP antigen. Nonspecific reactants are removed by washing. Peroxidase-conjugated anti-human antibodies are added to react with JCV-specific antibodies. Excess conjugate is removed by washing. Enzyme substrate and chromogen are added, and the color is allowed to develop. After adding the Stop Reagent, the resultant color change is quantified by a spectrophotometric reading of optical density (OD). Specimen OD readings are compared with Cut-Off Calibrator OD readings to determine results. Each specimen result is reported as an index value. A specimen with an index value that is greater than a specified upper cut-off is reported as positive for detectable JCV-specific antibodies, whereas a specimen with an index value less than the specified lower cut-off is reported as negative for detectable JCV-specific antibodies. A specimen with an index value that is equal to or between the upper and lower cut-off values is reported as indeterminate. An indeterminate result requires further evaluation in the confirmation (inhibition) assay.

In the confirmation assay, soluble JC VLP antigen will compete with plate bound JC VLP antigen for the JCV-specific antibodies present in the serum or plasma specimens. After washing away the unbound antibodies, peroxidase-conjugated anti-human antibodies are added and bind to any captured JCVspecific antibodies. Excess conjugate is removed by washing. Enzyme substrate and chromagen are added, and the color is allowed to develop. After adding the Stop Reagent, the resultant color change is quantified by a spectrophotometric reading of OD. The percent inhibition is calculated to confirm presence of JCV-specific antibodies in the specimens with a percent inhibition value that is greater than the specified cut-off are reported as positive for detectable JCV-specific antibodies, whereas specimens with percent inhibition values less than or equal to the cut-off are reported as negative for detectable JCV-specific antibodies.

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

Acceptance Criteria and Device Performance for STRATIFY JCV® DxSelect™

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present a "table of acceptance criteria" in the traditional sense, but rather demonstrates performance against the predicate device and established clinical guidelines. The key performance metrics evaluated are Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) with a validated laboratory methodology (the predicate device) and JCV antibody positivity rate in certain patient populations.

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The Focus Diagnostics Simplexa™ Flu A/B & RSV Direct assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and differentiation of influenza A virus, influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza A, influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established with clinical specimens collected during the 2010/2011 influenza season when 2009 H1N1 influenza and H3N2 were the predominant influenza A viruses in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Focus Diagnostics' Simplexa™ Flu A/B & RSV Positive Control Pack is intended to be used as a control with the Simplexa™ Flu A/B & RSV Direct kit. This control is not intended for use with other assays or systems.

The Simplexa™ Flu A/B & RSV Direct assay system is a real-time RT-PCR system that enables the direct amplification, delection and differentiation of human influenza A (Flu A) virus RNA, human influenza B (Flu B) virus RNA and RSV RNA from unprocessed nasopharyngeal swabs that have not undergone nucleic acid extraction. The system consists of the Simplexa™ Flu A/B & RSV Direct assay, the 3M Integrated Cycler (with Integrated Cycler Studio Software), the Direct Amplification Disc and associated accessories.

In the Simplexa™ Flu A/B & RSV Direct assay, bi-functional fluorescent probe-primers are used together with corresponding reverse primers to amplify Flu A, Flu B, RSV and internal control RNA. The assay provides three results; conserved regions of influenza A viruses (matrix gene) influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to detect RT-PCR failure and/or inhibition.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio software.

Here's a breakdown of the acceptance criteria and study details for the Simplexa™ Flu A/B & RSV Direct assay, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the document. However, the reported performance data from the clinical studies serve as the basis for demonstrating the device's acceptable performance. For clarity, I've listed the reported performance as if those were the implicit acceptance targets for the study.

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The Focus Diagnostics Simplexa™ C. difficile Universal Direct is a real-time polymerase chain reaction (PCR) assay and is intended for use on the 3M Integrated Cycler instrument for the detection of toxigenic Clostridium difficile toxin B gene (tcdB) in liquid or unformed stool samples from individuals suspected of C. difficile infection. This test aids in the diagnosis of Clostridium difficile associated disease (CDAD).

The test is a real-time polymerase chain reaction (PCR) amplification system that utilizes bifunctional fluorescent probe-primers for the detection of C. difficile in liquid or unformed stool. The Simplexa™ C. difficile Universal Direct kit contains primes, buffers and controls. The assay is composed of two principal steps: (1) Heat treatment of stool samples, (2) Amplification of the C. difficile DNA and internal control DNA using bi-functional fluorescent probe-primers together with reverse primers. The DNA internal control is used to monitor potential presence of PCR inhibitors. The assay targets a sequence which is in a well conserved region of C. difficile toxin B gene (tcdB).

1. Acceptance Criteria and Reported Device Performance

Note: For clinical performance, the acceptance criteria are not explicitly stated as numerical targets within the document provided. Instead, the performance is reported and implicitly compared to predicate devices or considered acceptable for the intended use. The reproducibility acceptance criteria are inferred from the 100% or >90% agreement shown in the predicate device data section of the comparison table.

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

• Reproducibility: A "panel" of contrived samples (high negative, medium positive) spiked with C. difficile bacterial stock was used. For each of the three sites, the Low Positive, Positive Control, High Negative, and No Template Control samples were tested in 30 replicates each (with 29 replicates for one medium positive sample at one site).
• Limit of Detection (LoD): The LoD was determined using three replicates in an initial screening phase, followed by confirmation using twenty replicates for two C. difficile bacterial strains.
• Analytical Reactivity: 20 different C. difficile strains were tested, each in triplicate.
• Cross-Reactivity: A total of 119 potential cross-reactants were tested. Each cross-reactant and baseline sample was tested in multiple replicates (implied at least 3, as mentioned in the interference section that "One replicate reported as "Invalid"... in initial run of three replicates").
• Interference: 21 potentially interfering substances were spiked into low positive C. difficile samples and tested. The results typically show 3/3 replicates detected for each substance and strain, with some exceptions tested in 5/5 or with repeat runs for invalid/not detected results.
• Clinical Studies: A total of 970 prospectively collected stool specimens were obtained.
  • Data Provenance:
    • Site 1: Prospectively collected fresh specimens from the East Coast of the US.
    • Site 2: Prospectively collected fresh specimens (and performed toxigenic culture for all specimens, including those from other sites) from the East Coast of the US.
    • Site 3: Prospectively collected clinical specimens from the West Coast of the US and Upper Mid-West of the US.

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

• Reproducibility, LoD, Analytical Reactivity, Cross-Reactivity, Interference: Ground truth for these analytical studies was established by preparing bacterial stocks and contrived samples with known concentrations and identities. This does not typically involve human experts in the same way clinical ground truth does. The experiments were likely designed and performed by trained laboratory personnel. The document does not specify the number or qualifications of these individuals.
• Clinical Studies:
  • Ground Truth Method: "Toxigenic Culture" (Direct Culture + Toxin Assay and Enriched Culture + Toxin Assay) was used as the reference method. This is a laboratory-based method.
  • Experts: The document does not specify the number of experts or their qualifications for establishing the toxigenic culture results. It states that "Site 2 conducted all direct and enriched toxigenic culture testing for all specimens," implying trained laboratory personnel rather than a panel of clinical experts for interpretation.

4. Adjudication Method for the Test Set

• Analytical Studies (Reproducibility, LoD, Analytical Reactivity, Cross-Reactivity, Interference): Adjudication methods are not explicitly described for these laboratory experiments. The results are typically quantitative or categorical (detected/not detected) based on the assay's output. Any "invalid" results (e.g., in reproducibility and interference sections) led to retesting or were noted.
• Clinical Studies: The reference method for clinical studies was "Toxigenic Culture." The document does not describe any specific adjudication process involving multiple experts for the toxigenic culture results. "Site 2 conducted all direct and enriched toxigenic culture testing."

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 performed. This study focuses on an in vitro diagnostic (IVD) assay (PCR) for detecting a pathogen, not on human readers interpreting images or data with or without AI assistance. Therefore, there is no effect size of human readers improving with AI assistance.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

• Yes, this study primarily assesses the standalone performance of the Simplexa™ C. difficile Universal Direct assay (an algorithm-based PCR method) without human interpretation as part of the primary diagnostic output. The device itself is an automated real-time PCR system. While human operators are involved in sample preparation and running the instrument, the result (detected/not detected) is generated automatically by the "detection techniques" of "Real time PCR with bi-functional fluorescent probe-primers using the 3M Integrated Cycler."

7. The Type of Ground Truth Used

• Analytical Studies: Ground truth was established through known concentrations of bacterial strains and contrived samples for LoD, analytical reactivity, cross-reactivity, and interference studies.
• Clinical Studies: Ground truth for the clinical agreement study was established using Toxigenic Culture (Direct Culture + Toxin Assay and Enriched Culture + Toxin Assay). This is a laboratory-based gold standard for detecting toxigenic C. difficile.

8. The Sample Size for the Training Set

• The document describes premarket notification (510(k)) studies for a diagnostic device. It does not mention a "training set" in the context of machine learning. The studies described are validation studies (analytical and clinical) performed on the final device. Therefore, a specific sample size for a training set is not applicable in this context.

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

• As a "training set" for machine learning is not applicable in this context, the method for establishing its ground truth is also not applicable.

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The STRATIFY JCVTM Antibody ELISA testing service provided by Focus Diagnostics is intended for the qualitative detection of antibodies to John Cunningham virus in human serum or plasma. The assay is intended for use in conjunction with other clinical data, in multiple sclerosis and Crohn's disease patients receiving natalizumab therapy, as an aid in risk stratification for progressive multifocal leukoencephalopathy development. The assay is for professional use only and is to be performed only at Focus Diagnostics' Reference Laboratory.

The assay is not intended for donor screening. The performance of this assay has not been established for use in other immunocompromised patient populations or in neonates and pediatrics patient populations.

The STRATIFY JCV™ Antibody ELISA consists of two devices. The first is an initial detection ELISA and the second device is a confirmatory (inhibition) ELISA. Both tests utilize the same recombinant antigen which is used in two different formats as described in section L. The devices include the following reagents; Recombinant JC virus like particles (VLP), a JCV high and low positive controls, consisting of human sera that is positive for JCV antibodies, and JCV negative control consisting of human sera that is negative for JCV antibodies. The conjugate, substrate, wash buffers and blocking buffers needed for the test are not supplied with the device and are listed together with other reagents and consumables in the device labeling.

Here's a breakdown of the acceptance criteria and the studies that support the performance of the STRATIFY JCV™ Antibody ELISA, based on the provided 510(k) summary:

Acceptance Criteria and Reported Device Performance

Study Details

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

• Precision Studies (Detection & Confirmation):
  • Sample Size: 90 aliquots for each plasma and serum level (High Positive, Indeterminate, Low Positive, Negative) in the detection assay. The indeterminate pools then subjected to confirmation (90 plasma indeterminate, 86 serum indeterminate).
  • Data Provenance: Not explicitly stated, but likely from laboratory internal samples/controls, potentially spiked to achieve different concentrations.
• Analytical Specificity (Cross-Reactivity - Spiked Antibodies):
  • Sample Size: 3 replicates for each of 3 spiked antibodies (total 9 tests for serum, 9 for plasma).
  • Data Provenance: Laboratory, using commercially available human antibodies spiked into JCV negative serum/plasma.
• Analytical Specificity (Cross-Reactivity - Seroprevalence):
  • Sample Size: Panels of up to twenty remnant specimens (e.g., 20 for C. pneumoniae, HSV6, VZV, Candida, HSV1, HSV2; 4 for T. pallidum; 9 for M. pneumoniae; 15 for CMV; 20 for HIV1). Total 188 samples across various sero-positive groups.
  • Data Provenance: Remnant clinical specimens, likely retrospective from various patient populations.
• Analytical Specificity (Interferences - Endogenous Substances):
  • Sample Size: Not explicitly stated as a number of samples, but involved spiking a single low-concentration JCV antibody native serum and plasma panel with various interferents and comparing to baseline.
  • Data Provenance: Laboratory, using native serum/plasma samples and spiked interferents.
• Analytical Specificity (Interferences - Concomitant Medications):
  • Sample Size: Subset of 585 MS patients from the AFFIRM study.
  • Data Provenance: Prospective clinical trial (AFFIRM study) data, with serial samples collected over 30 months. Patients were treated for Multiple Sclerosis.
• False Negative Rate (JCV Viruric Patients):
  • STRATA Study: 204 viruric patients.
  • STRATIFY-1 Study: 186 urinary JCV DNA positive subjects (out of 1073 total subjects).
  • Data Provenance: Prospective clinical studies (STRATA and STRATIFY-1), involving MS patients.
• Method Comparison with LDT:
  • Sample Size: 200 samples (62 negative, 71 low positives near cut-point, 67 positive).
  • Data Provenance: Not explicitly stated, but presumably clinical samples, likely retrospective.
• Matrix Comparison:
  • Sample Size: 50 paired plasma and serum samples.
  • Data Provenance: Clinical samples (presumably from patients).
• Clinical Performance (PML Risk Stratification - Pre-PML Samples):
  • Sample Size: 37 available serum samples from confirmed PML patients.
  • Data Provenance: Retrospective collection of serum samples from patients who developed PML, collected specifically from clinical trials and post-marketing reports prior to PML diagnosis.
• Clinical Performance (PML Risk Stratification - MS Population JCV Positivity):
  • Sample Size: 5,896 MS patients.
  • Data Provenance: Clinical trials (AFFIRM, TYGRIS-US, STRATIFY-1) and a national MS registry (Sweden). This is a large, geographically diverse, retrospective and potentially prospective (from ongoing studies) cohort of MS patients.
• Clinical Performance (JCV Antibody Prevalence - CD Patients):
  • Sample Size: 313 CD patients.
  • Data Provenance: Two completed Phase 3 clinical trials (CD301 and CD303) of natalizumab in Crohn's disease patients. Retrospective.

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

• The document does not mention the use of experts to establish ground truth for the test sets (patient samples, viruric samples, etc.). The ground truth for these studies relies on other laboratory methods (e.g., urinary JCV DNA positivity for viruric patients) or clinical diagnoses (e.g., confirmed PML diagnosis for the pre-PML samples).

4. Adjudication method for the test set:

• The document does not describe an adjudication method involving experts for any of the test sets. Ground truth is established by laboratory results (e.g., confirmed urinary JCV DNA positivity) or clinical diagnosis of PML, not by expert consensus on the samples themselves.

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. This is an ELISA (Enzyme-Linked Immunosorbent Assay) for detecting antibodies, not an imaging device or AI-assisted diagnostic tool that would involve human readers. Therefore, an MRMC study is not applicable and was not performed.

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

• Yes, effectively. The STRATIFY JCV™ Antibody ELISA is a laboratory assay. Its performance characteristics (precision, specificity, false negative rates, and clinical performance) are evaluated as a standalone test, meaning the results are generated directly by the assay without real-time human interpretation or modification of the assay output. Human intervention occurs in performing the assay and interpreting the final quantitative (nOD, % Inhibition) or qualitative (Positive/Negative/Indeterminate) results based on predefined cut-offs.

7. The type of ground truth used:

• JCV Viruric Patients: JCV DNA positivity in urine (confirmed infection).
• PML Risk Stratification: Clinical diagnosis of Progressive Multifocal Leukoencephalopathy (PML), along with historical records of natalizumab treatment and prior immunosuppressant use.
• Method Comparison: The Laboratory Developed Test (LDT) served as the comparative method, acting as a de facto reference in that specific study.
• For other analytical studies (precision, cross-reactivity, interference), ground truth was established by known concentrations/statuses of analytes or known presence/absence of cross-reactants/interferents.

8. The sample size for the training set:

• The document does not explicitly describe a "training set" in the context of a machine learning algorithm. This is a traditional IVD ELISA kit.
• However, the cut-off for the assay (nOD > 0.25 positive,

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The Focus Diagnostics Simplexa™ Flu A/B & RSV assay is intended for use on the 3M Integrated Cycler instrument for the in vitro qualitative detection and discrimination of influenza A virus, influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS) from human patients with signs and symptoms of respiratory tract infection in conjunction with clinical and epidemiological risk factors. This test is intended for use as an aid in the differential diagnosis of influenza A, influenza B, and RSV viral infections in humans and is not intended to detect influenza C.

Negative results do not preclude influenza virus or RSV infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established during the 2010 influenza season when 2009 H1N1 influenza was the predominant influenza A virus in circulation. When other influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

The test is a real-time RT-PCR amplification system that utilizes a bi-functional fluorescent probe-primer for the detection and differentiation of human influenza A virus RNA, human influenza B virus RNA and respiratory syncytial virus RNA in nasopharyngeal swabs (NPS). The assay is composed of two principal steps: (1) extraction of RNA from patient specimens, (2) A bi-functional fluorescent probe-primer is used together with a reverse primer to amplify a specific target (for each analyte and the RNA internal control). The assay provides three results; conserved regions of influenza A viruses (matrix gene), influenza B viruses (matrix gene) and RSV (M gene) are targeted to identify these viruses in the specimen. An RNA internal control is used to monitor the extraction process and to detect RT-PCR inhibition.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio Software.

The Focus Diagnostics Simplexa™ Flu A/B & RSV assay is intended for the qualitative detection and discrimination of influenza A virus, influenza B virus, and respiratory syncytial virus (RSV) RNA in nasopharyngeal swabs (NPS).

Here's an analysis of the provided information:

1. Table of Acceptance Criteria and Reported Device Performance:

The document doesn't explicitly state "acceptance criteria" as distinct numerical thresholds for PPA/NPA. Instead, it provides the clinical agreement percentages, which are implicitly the performance targets for demonstrating substantial equivalence. The table below summarizes the reported clinical agreement from the clinical agreement study for both prospective and retrospective samples.

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

• Total Sample Size: 735 nasopharyngeal swabs (NPS).
• Provenance:
  • Prospective Samples: 558 specimens, collected from patients with signs and symptoms of viral respiratory tract infection.
  • Retrospective Samples: An unspecified number (the document mentions "banked specimens with signs and symptoms of viral respiratory tract infection," and the individual category summaries provide the counts for retrospective testing: 177 for Influenza A, 177 for Influenza B, and 177 for RSV). The combined numbers in the tables (e.g., 553 for prospective Flu A, 553 for prospective Flu B, etc.) indicate how the 558 prospective samples were distributed across the different analytes, and similarly for retrospective samples from the total of 735.
• Country of Origin: Not explicitly stated, but typically for FDA submissions, these studies are conducted in the US.

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

This information is not provided in the document. The ground truth was established by laboratory methods, not expert visual assessment.

4. Adjudication method for the test set:

This information is not applicable as the ground truth was established by reference laboratory methods (high-performance NAT and culture/DFA), not by human interpretation requiring adjudication.

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:

Not applicable. This study is for an in vitro diagnostic device (RT-PCR assay), not an imaging-based AI diagnostic that typically involves human readers. Therefore, an MRMC study and analysis of human reader improvement with AI assistance were not performed.

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

Yes, this was effectively a standalone study. The Simplexa™ Flu A/B & RSV assay is an automated RT-PCR system. Its performance was compared directly against reference methods (high-performance NAT and culture/DFA) without human interpretation steps that would integrate with the device's output. The device itself is the "standalone algorithm/system."

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

• Influenza A Virus: High performance FDA cleared nucleic acid test (NAT).
• Influenza B Virus: High performance FDA cleared nucleic acid test (NAT).
• Respiratory Syncytial Virus (RSV): Culture/DFA (Direct Fluorescent Antibody).

8. The sample size for the training set:

The document does not explicitly mention a "training set" in the context of device development. This is typical for in vitro diagnostic assays like RT-PCR, where analytical performance (e.g., Limit of Detection, analytical reactivity, cross-reactivity) is established using characterized strains and then clinical performance is validated on clinical samples, rather than a machine learning training/validation split.

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

As no explicit "training set" or machine learning approach is described for the device, this information is not applicable. The analytical characteristics are determined using known concentrations of viral strains and the clinical performance is compared against established reference methods.

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The Integrated Cycler and accompanying Studio Software are intended for in vitro diagnostic use in conjunction with legally marketed Simplexa™ reagent kits and assay protocols labeled for in vitro diagnostic use.

The Integrated Cycler is a rapid real-time Polymerase Chain Reaction (PCR) thermocycler used for identification of nucleic acid from prepared biological samples. The instrument utilizes disc media to contain and to process samples. The instrument uses real-time flourometric detection to identify targets within the sample wells. The instrument's operation parameters are controlled by the use of an external personal computer and associated software. This instrument is intended to be used by laboratory professionals trained in laboratory techniques and in a laboratory environment.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio Software.

The provided document describes the 3M Integrated Cycler, a thermocycler for real-time PCR. However, the document, being a 510(k) Summary for a device, primarily focuses on establishing "substantial equivalence" to a predicate device rather than presenting detailed performance data from a specific clinical study with granular acceptance criteria and results for the device itself.

Here's an breakdown of the information requested, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not provide a table of acceptance criteria or specific numerical performance metrics for the 3M Integrated Cycler itself. Instead, it states that performance characteristics like Reproducibility, Limit of Detection, Analytical Reactivity, Cross-Reactivity, and Clinical Agreement "was assessed during the clearance of the assay (K100148) and will be addressed for each assay to be run on this system." This indicates that the performance criteria and their fulfillment are specific to the assays (reagent kits) used with the cycler, not the cycler hardware itself in this 510(k) submission.

Therefore, a table cannot be constructed from the provided text.

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

The document does not provide information on the sample size used for a test set for the 3M Integrated Cycler itself. It defers these details to the clearance of individual assays (reference K100148).
Data provenance (country of origin, retrospective/prospective) is also not mentioned for the cycler's evaluation.

3. Number of Experts Used to Establish Ground Truth and Qualifications

This information is not provided in the document. The document focuses on the device (thermocycler) and its equivalence to a predicate, not on the performance of a specific diagnostic assay that would typically involve expert-established ground truth.

4. Adjudication Method

This information is not provided in the document.

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

No mention of an MRMC comparative effectiveness study, human readers, or AI assistance is found in this document. The device is a thermocycler, not an AI-powered diagnostic tool requiring human reader comparison.

6. Standalone (Algorithm Only) Performance Study

The concept of "standalone performance" for an algorithm is not applicable here as the device is a hardware thermocycler, not an algorithm. The document speaks to the functionality of the thermocycler in conjunction with accompanying software and reagent kits.

7. Type of Ground Truth Used

The type of ground truth for performance metrics (Reproducibility, LOD, etc.) "was assessed during the clearance of the assay (K100148)". This implies that the ground truth would be established based on the specific assay being cleared, likely involving known positive and negative controls, spiked samples, and potentially clinical samples with confirmed diagnoses (pathology, clinical outcomes, etc.), but this is not detailed for the cycler itself in this document.

8. Sample Size for the Training Set

The document does not provide information about a training set sample size, as it describes a hardware device rather than a machine learning algorithm that would typically require a training set.

9. How Ground Truth for the Training Set Was Established

As there's no mention of a training set or machine learning algorithm, the establishment of ground truth for a training set is not applicable to this document.

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The Focus Diagnostics Simplexa™ Influenza A H1N1 (2009) assay is intended for use on the 3M Integrated Cycler as part of the Microfluidic Molecular System for the in vitro qualitative detection and differentiation of influenza A and 2009 H1N1 influenza viral RNA in nasopharyngeal swabs (NPS), nasal swabs (NS), and nasopharyngeal aspirates (NPA) from human patients with signs and symptoms of respiratory infection in conjunction with clinical and epidemiological risk factors.

Negative results do not preclude influenza virus infection and should not be used as the sole basis for treatment or other patient management decisions.

Performance characteristics for influenza A were established during the 2009-2010 influenza season when 2009 H1N1 influenza was the predominant influenza A virus in circulation. When other Influenza A viruses are emerging, performance characteristics may vary.

If infection with a novel Influenza A virus is suspected based on current clinical and epidemiological screening criteria recommended by public health authorities, specimens should be collected with appropriate infection control precautions for novel virulent Influenza viruses and sent to state or local health department for testing. Viral culture should not be attempted in these cases unless a BSL 3+ facility is available to receive and culture specimens.

Simplexa™ Influenza A H1N1 (2009) test kit is a nucleic acid amplification test that uses real-time reverse transcriptase polymerase chain reaction (RT-PCR) amplification to enable simultaneous and distinct detection of influenza A and 2009 H1N1 influenza in a single reaction from nasophayngeal swabs (NPS), nasal swabs (NS), and nasopharyngeal aspirates (NPA). The assay combines real-time PCR amplification with fluorescent signal detection technology. A bi-functional fluorescent probe-primer is used together with a reverse primer to amplify a specific target (for each analyte and internal control). A fluorescent signal is generated after the separation of the fluorophore from the quencher as a result of the binding of a probe element to the extended RNA fragment synthesized during amplification.

The 3M Integrated Cycler is a rapid real-time Polymerase Chain Reaction thermocycler used for the identification of nucleic acid from prepared biological samples. The instrument utilizes disk media to contain and to process samples. The instrument uses real time flourometric detection to identify targets within the sample wells. The instrument is controlled by an external computer running the Integrated Cycler Studio Software. Together, the instrument, software and test kit are referred to as the "Microfluidic Molecular System."

Here's a breakdown of the acceptance criteria and study details for the Simplexa™ Influenza A H1N1 (2009) assay based on the provided document:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a separate table with target values for clinical performance as commonly seen for medical devices. However, the reported performance metrics (Positive Percent Agreement - PPA, Negative Percent Agreement - NPA) from the clinical agreement studies serve as the de-facto acceptance criteria demonstrated by the device.

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

• Prospective Data:

  • Nasal/Nasopharyngeal Swabs: 299 specimens initially collected. After exclusions due to lack of consensus among reference assays (10 for Influenza A, 9 additional for H1N1 subtype sequencing), the sample sizes used for agreement calculations are:
    • H1N1 Detected: 101
    • H1N1 Not Detected: 179
    • Influenza A Detected: 116
    • Influenza A Not Detected: 173
  • Nasopharyngeal Aspirates: 112 specimens initially collected. After exclusions due to lack of consensus among reference assays (5 for Influenza A, 3 additional for H1N1 subtype sequencing), the sample sizes used for agreement calculations are:
    • H1N1 Detected: 24
    • H1N1 Not Detected: 80
    • Influenza A Detected: 31
    • Influenza A Not Detected: 76
  • Provenance: Collected from patients with signs and symptoms of influenza-like illness at three sites: Austin, TX (September 2009) and the New South Wales region of Australia (July - September 2009). The collected specimens were blinded and randomly distributed to 3 U.S. clinical laboratories for testing.

• Retrospective Data:

  • Nasal/Nasopharyngeal Swabs: 214 specimens initially collected from the Focus Sample Bank. After exclusions due to lack of consensus among reference assays (3 for Influenza A, 1 additional for H1N1 subtype sequencing), the sample sizes used for agreement calculations are:
    • H1N1 Detected: 57
    • H1N1 Not Detected: 153 (including 1 indeterminate)
    • Influenza A Detected: 132 (including 1 indeterminate)
    • Influenza A Not Detected: 79
  • Nasal Washes: 2 specimens (both positive for 2009 H1N1 influenza and Influenza A by both methods).
  • Provenance: Focus Sample Bank (implying archival samples). No specific country of origin is mentioned beyond "Focus Sample Bank."

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

The document does not specify the number of experts or their qualifications for establishing the ground truth. It refers to a "composite reference method" which includes multiple validated assays, but not human expert review for establishing ground truth.

4. Adjudication Method for the Test Set

The ground truth was established using a composite reference method which included:

• Luminex xTAG RVP Flu A target
• A validated PCR assay using primer and probe sequences published by the CDC
• A well-characterized PCR followed by sequencing.

Specimens were excluded from analysis if there was "no consensus among the reference assays" for the influenza A result or if sequencing data was not available for subtyping. This implies a form of consensus/adjudication among the reference methods, but not by human experts in the traditional sense as a separate step.

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 performed. This study evaluates the Simplexa™ Influenza A H1N1 (2009) assay in a standalone capacity against a composite reference (ground truth), not in comparison to or in assistance with human readers. Therefore, there is no effect size reported for human readers improving with AI vs without AI assistance.

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

Yes, this was a standalone performance study. The Simplexa™ Influenza A H1N1 (2009) assay's performance was evaluated by directly comparing its results to the established composite reference ground truth. There is no mention of human-in-the-loop involvement in the performance evaluation.

7. The Type of Ground Truth Used

The ground truth used was a composite reference method comprised of:

• Luminex xTAG RVP Flu A target
• A validated PCR assay using primer and probe sequences published by the CDC
• A well-characterized PCR followed by sequencing.

8. The Sample Size for the Training Set

The document does not explicitly mention a separate "training set" or its sample size for the development of the Simplexa™ Influenza A H1N1 (2009) assay. The provided studies focus solely on the performance of the developed assay, typically referring to validation or test sets.

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

Since a "training set" is not explicitly discussed, the method for establishing its ground truth is also not specified. It can be inferred that similar validated molecular methods would have been used during the assay's development phase.

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