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The Aptima Neisseria gonorrhoeae (GC) Assav is an in vitro qualitative nucleic acid amplification (NAAT) the detection of ribosomal RNA (rRNA) from Neisseria gonorrhoeae (GC) to aid in the diagnosis of gonocccal urogenital disease using the Panther System. The assay may be used to test male urine specimens from symptomatic and asymptomatic individuals.

The Aptima GC assay is a target amplification nucleic acid probe test for in vitro qualitative detection of ribosomal RNA (rRNA) from Neisseria gonorrhoeae (GC). The Aptima Neisseria gonorrhoeae Assay combines the technologies of target capture, transcription-mediated amplification (TMA), and hybridization protection assay (HPA). Specimens are collected and transferred into their respective specimen transport tubes. The transport solution in these tubes releases the rRNA target and protects it from degradation during storage. When the Aptima Neisseria gonorrhoeae Assay is performed in the laboratory, the target rRNA molecule is isolated from the specimens by use of a capture oligomer via target capture that utilizes magnetic microparticles. The capture oligomer contains a sequence complementary to a specific region of the target molecule as well as a string of deoxyadenosine residues. During the hybridization step, the sequence specific region of the capture oligomer binds to a specific region of the target molecule. The capture oligomer:target complex is then captured out of solution by decreasing the temperature of the reaction to room temperature. This temperature reduction allows hybridization to occur between the deoxyadenosine region on the capture oligomer and the poly-deoxythymidine molecules that are covalently attached to the magnetic particles. The micro particles, including the captured target molecule bound to them, are pulled to the side of the reaction vessel using magnets and the supernatant is aspirated. The particles are washed to remove residual specimen matrix that may contain amplification reaction inhibitors. After the target capture steps are completed, the specimens are ready for amplification. Target amplification assays are based on the ability of complementary oligonucleotide primers to specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The Hologic TMA reaction replicates a specific region of the 16S rRNA from GC via DNA intermediates. A unique set of primers is used for the target molecule. Detection of the rRNA amplification product sequences (amplicon) is achieved using nucleic acid hybridization. A single-stranded chemiluminescent DNA probe, which is complementary to a region of the target amplicon, is labeled with an acridinium ester molecule. The labeled DNA probe combines with amplicon to form stable RNA:DNA hybrids. The Selection Reagent differentiates hybridized from unhybridized probe, eliminating the generation of signal from unhybridized probe. During the detection step, light emitted from the labeled RNA:DNA hybrids is measured as photon signals in a luminometer, and are reported as Relative Light Units (RLU). The device reagents are identical to the Aptima Neisseria gonorrhoeae Assay reagents for use on the Tigris DTS system but are intended for use on the Panther system with different specimen type indications. The Panther and Tigris DTS systems use the same principles of operation.

Here's a breakdown of the acceptance criteria and study details for the Aptima Neisseria gonorrhoeae Assay, based on the provided FDA 510(k) summary:

This device is an in vitro qualitative nucleic acid amplification test (NAAT) for the detection of Neisseria gonorrhoeae (GC) rRNA to aid in the diagnosis of gonococcal urogenital disease in male urine specimens using the Panther System. It does not appear to involve AI assistance or human reader studies.

1. Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state pre-defined acceptance criteria for clinical performance (sensitivity and specificity) as a set of numerical thresholds. Instead, it states that the study data demonstrate that performance of the Aptima Neisseria gonorrhoeae Assay on the Panther system is substantially equivalent to that of currently FDA-cleared assays for male urine specimens.

However, analytical studies do present performance metrics that implicitly act as acceptance criteria, for example, for Limit of Detection (LoD), precision, and specificity (no interference).

Here's a summary of reported device performance based on the provided text:

Table of Reported Device Performance

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

• Clinical Test Set:
  • Total Enrolled Subjects: 2085 male subjects.
  • Evaluable Subjects: 1959 male subjects (126 subjects not evaluable).
  • Specimens Included in Performance Analysis: 1958 male urine specimens (one specimen with final GC equivocal result was excluded).
  • Data Provenance: Prospective, multi-center clinical study conducted at 11 geographically and ethnically diverse US clinical sites.
    • Sites included obstetrics and gynecology, family planning, and STI clinics.
    • Specimens were collected from symptomatic and asymptomatic men.

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

• The document does not explicitly state the number of experts used to establish ground truth for the clinical test set.
• The ground truth (Patient Infected Status - PIS) was established using up to 3 FDA-cleared NAATs (Nucleic Acid Amplification Tests). This implies that a consensus or reference standard approach using multiple existing, cleared diagnostic methods was used, rather than individual expert review or pathological examination for individual cases.

4. Adjudication Method for the Test Set

• The document states that the Patient Infected Status (PIS) was established using "up to 3 FDA-cleared NAATs". This indicates a composite reference standard approach.
• The specific adjudication rule (e.g., 2/3 positive, 3/3 positive) is not detailed, but the use of multiple FDA-cleared methods implies a robust, multi-test consensus for the ground truth.

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

• No, an MRMC comparative effectiveness study was not done.
• This device is an in vitro diagnostic (IVD) assay (a qualitative nucleic acid amplification test), not an imaging AI device that assists human readers. Therefore, there is no "human-in-the-loop" component or an effect size for human readers improving with AI assistance.

6. Standalone Performance

• Yes, standalone performance was done.
• The described clinical study evaluates the performance of the "Aptima Neisseria gonorrhoeae Assay on the Panther System" directly against a composite reference standard (PIS derived from FDA-cleared NAATs). This is a standalone performance assessment of the algorithm/device itself, without human intervention in the result interpretation.

7. Type of Ground Truth Used

• The ground truth used for the clinical test set was a composite reference standard, referred to as "Patient Infected Status (PIS)".
• PIS was established by testing male urine specimens with "up to 3 FDA-cleared NAATs". This is a highly robust method, relying on multiple well-validated diagnostic tests to determine the true infection status.

8. Sample Size for the Training Set

• The document does not specify the sample size for the training set.
• This document is a 510(k) summary for premarket notification, focusing on the validation of the device for its intended use. Information regarding the development and training of the assay (e.g., specific molecular sequences, probe design) is generally proprietary and not included in this type of submission. The focus is on the performance of the final, locked version of the device.

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

• The document does not specify how the ground truth for any potential training set was established, nor explicitly mention a distinct training set.
• For an IVD such as this, the "training" (or development and optimization) typically involves extensive analytical studies (e.g., primer design, probe specificity, optimization of reaction conditions, LoD determination, cross-reactivity testing) rather than machine learning-style "training data" with a "ground truth" in the same sense as an AI imaging algorithm. The core of the assay relies on well-established molecular biology principles and target identification.

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The Aptima Combo 2® Assay is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection and differentiation of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (GC) to aid in the diagnosis of chlamydial and/or gonococcal urogenital disease using the Panther® System as specified.

On the Panther System, the assay may be used to test the following specimens from symptomatic and asymptomatic individuals: clinician-collected endocervical, vaginal and male urethral swab specimens, clinician-collected gynecological specimens collected in the PreservCyt® Solution, patient-collected vaginal swab specimens, 1 and female and male urine specimens.

1 Patient-collected vaginal swab specimens are an option for screening women when a pelvic exam is not otherwise indicated. The vaginal and multitest swab specimen collection kits are not for home use.

Clearance of this pre-market application will add female urine as an acceptable specimen type using the Aptima Combo 2 assay on the Panther system.

The Aptima Combo 2 Assay combines the technologies of target capture, Transcription-Mediated Amplification (TMA), and Dual Kinetic Assay (DKA). Specimens are collected and transferred into their respective specimen transport tubes. The transport solutions in these tubes release the rRNA targets and protect them from degradation during storage. When the Aptima Combo 2 Assay is performed in the laboratory, the target rRNA molecules are isolated from specimens by use of capture oligomers via target capture that utilizes magnetic microparticles. The capture oligomers contain sequences complementary to specific regions of the target molecules as well as a string of deoxyadenosine residues. A separate capture oligomer is used for each target. During the hybridization step, the sequence specific regions of the capture oligomers bind to specific regions of the target molecules. The capture oligomer:target complex is then captured out of solution by decreasing the temperature of the reaction to room temperature. This temperature reduction allows hybridization to occur between the deoxyadenosine region on the capture oligomer and the poly-deoxythymidine molecules that are covalently attached to the magnetic particles. The microparticles, including the captured target molecules bound to them, are pulled to the side of the reaction vessel using magnets and the supernatant is aspirated. The particles are washed to remove residual specimen matrix that may contain amplification reaction inhibitors. After the target capture steps are completed, the specimens are ready for amplification.

Target amplification assays are based on the ability of complementary oligonucleotide primers to specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The Aptima Combo 2 Assay replicates a specific region of the 23S rRNA from CT and a specific region of the 16S rRNA from GC via DNA intermediates. A unique set of primers is used for each target molecule. Detection of the rRNA amplification product sequences (amplicon) is achieved using nucleic acid hybridization. Single-stranded chemiluminescent DNA probes, which are complementary to a region of each target amplicon, are labeled with different acridinium ester molecules. The labeled DNA probes combine with amplicon to form stable RNA:DNA hybrids. The Selection Reagent differentiates hybridized from unhybridized probe, eliminating the generation of signal from unhybridized probe. During the detection step, light emitted from the labeled RNA:DNA hybrids is measured as photon signals in a luminometer, and are reported as Relative Light Units (RLU). In DKA, differences in the kinetic profiles of the CT and GC labeled probes allow for the differentiation of signal; kinetic profiles are derived from measurements of photon output during the detection read time. The chemiluminescent detection for CT signal has very rapid kinetics and has the "flasher" kinetic type. The chemiluminescent detection reaction for GC signal is relatively slower and has the "glower" kinetic type. Assay results are determined by a cut-off based on the total RLU and the kinetic curve type.

The Aptima Combo 2 assay has been designed for and validated on the Panther system. The Panther system is an integrated hardware and software system that together with the Aptima Combo 2 assay fully automates all the steps necessary to perform the assay from sample preparation through amplification of nucleic acid, detection, data reduction and amplicon inactivation.

Here's an analysis of the provided text regarding the Aptima Combo 2 Assay (Panther System), focusing on acceptance criteria and the supporting study:

The provided document describes a 510(k) premarket notification for the Aptima Combo 2 Assay (Panther System) to add female urine as an acceptable specimen type. The study aimed to demonstrate substantial equivalence to the predicate device, which already included other specimen types.

1. Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in a table format with numerical targets. Instead, it presents the Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA) of the device compared to a Composite Comparator Algorithm (CCA) for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) in female urine samples. For regulatory clearance, these performance metrics are implicitly the acceptance criteria; the observed performance must be deemed sufficient for the intended use and comparable to similar marketed devices.

Based on the performance tables provided, here's a summary of the reported device performance, which likely served as the basis for acceptance:

Reported Performance of Aptima Combo 2 Assay (Panther System) for Female Urine

Note: The confidence intervals provide the range within which the true PPA/NPA is likely to fall. For asymptomatic GC, the PPA has a wider confidence interval due to a smaller number of positive cases.

2. Sample Size and Data Provenance

• Sample Size for Test Set:
  • Total subjects initially enrolled: 2640
  • Subjects with valid Aptima Combo 2 Assay results on Panther System: 2581
  • Evaluable subjects for performance (conclusive CCA status): 2580
  • Final Sample Size for CT performance: 2572 (1379 symptomatic, 1193 asymptomatic) after accounting for equivocal results and non-evaluable subjects.
  • Final Sample Size for GC performance: 2579 (1383 symptomatic, 1196 asymptomatic) after accounting for equivocal results and non-evaluable subjects.
• Data Provenance: Retrospective study.
  • Specimens originated from women enrolled in a previously completed prospective study.
  • The study participants (women) were enrolled from 17 geographically and ethnically diverse US clinical sites, including family planning, academic centers, and public health clinics.

3. Number of Experts and Qualifications for Ground Truth

The document does not specify the number of experts used to establish the ground truth or their qualifications. The ground truth (Composite Comparator Algorithm, CCA) was established using multiple FDA-cleared NAATs, not directly by human experts adjudicating individual cases based on clinical information or pathology.

4. Adjudication Method for the Test Set

The adjudication method used to establish the Composite Comparator Algorithm (CCA) for the ground truth was:

• 2 out of 3 rule: When 2 out of 3 FDA-cleared CT/GC NAATs were positive, the CCA was considered positive. When 2 out of 3 NAATs were negative, the CCA was considered negative.
• Tie-breaker: If the results from the initial two comparator NAATs did not determine the CCA, a third FDA-cleared CT/GC NAAT was performed using remnant urine samples to determine the CCA.

This is a form of consensus-based ground truth, but using other diagnostic tests rather than direct clinical expert consensus.

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

No MRMC comparative effectiveness study was done. This study evaluated the standalone performance of a diagnostic assay (Aptima Combo 2 Assay) against a reference standard (CCA), not the effect of AI assistance on human readers.

6. Standalone Performance

Yes, a standalone performance study was done. The entire clinical study described evaluates the performance of the Aptima Combo 2 assay on the Panther System (the algorithm/device itself) directly against the Composite Comparator Algorithm (CCA) without human interpretation as part of the primary outcome measure. The PPA and NPA values reported are the standalone performance metrics.

7. Type of Ground Truth Used

The ground truth used was a Composite Comparator Algorithm (CCA), which was derived from the results of multiple (up to 3) FDA-cleared nucleic acid amplification tests (NAATs). While this is a common method for establishing a "gold standard" in diagnostic test evaluations, it is not direct pathology, clinical outcomes data, or expert consensus in the traditional sense of clinicians reviewing patient records or images. It establishes the "truth" based on a highly sensitive and specific panel of existing diagnostic tools.

8. Sample Size for the Training Set

The document does not provide information on the sample size for a training set. This is a diagnostic assay (a lab test), not an AI/machine learning model in the typical sense that would require a separate, explicit "training set" for model parameters. The "development" or "training" of such an assay involves reagent formulation, assay protocol optimization, and establishing cut-offs, typically done using characterized samples, but not usually reported with a distinct "training set" size in the same manner as an AI algorithm. The study described is a clinical validation or "test set" evaluation.

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

As mentioned above, there is no explicit "training set" described in the context of this 510(k) submission. The performance study evaluated the device against a CCA, as detailed in point 4 and 7.

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The cobas® CT/NG on the cobas® 6800/8800 system is an automated, qualitative in vitro nucleic acid diagnostic test, that utilizes real-time polymerase chain reaction (PCR), for the direct detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) DNA in male and female urine, clinician-instructed self-collected vaginal swab specimens (collected in a clinical setting), clinician-collected vaginal swab specimens, and endocervical swab specimens, all collected in cobas® PCR Media (Roche Molecular Systems, Inc.), and cervical specimens collected in PreservCyt® solution. This test is intended as an aid in the diagnosis of chlamydial and gonococcal disease in both symptomatic and asymptomatic individuals.

cobas® CT/NG is a new qualitative test performed on the cobas® 6800 System and cobas® 8800 System. cobas® CT/NG enables the detection of CT/NG DNA in endocervical, vaginal, urine and cervical specimens of infected female patients and urine specimens in infected male patients. Target-specific primers and two probes are used to detect but not discriminate between the CT cryptic plasmid and the ompA gene. Additionally, target-specific primers and two probes are used to detect but not discriminate between two conserved sequences in the NG DR-9 region. The DNA Internal Control, used to monitor the entire sample preparation and PCR amplification process, is introduced into each specimen during sample processing. In addition, the test utilizes a low titer positive and a negative control. cobas® CT/NG is based on fully automated sample preparation (nucleic acid extraction and purification) followed by PCR amplification and detection. The cobas® 6800/8800 Systems consist of the sample supply module, the transfer module, the processing module, and the analytic module. Automated data management is performed by the cobas® 6800/8800 software which assigns test results for all tests as positive, negative or invalid. Results can be reviewed directly on the system screen, exported, or printed as a report.

Here's a breakdown of the acceptance criteria and study information for the cobas® CT/NG for use on the cobas® 6800/8800 Systems device, extracted from the provided text:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the clinical performance and reproducibility study results. The device aims for high sensitivity, specificity, and reproducibility.

Table of Acceptance Criteria and Reported Device Performance

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

Clinical Performance Study:

• Total Subjects Enrolled: 5,197
• Eligible Subjects: 5,105
• Evaluable Subjects (Prospective): 5,053 (3,860 females, 1,193 males)
• Archived Specimens (Female): 371 urogenital samples from 295 female subjects (used for NG detection). These originated from a previous clinical study for cobas® CT/NG v2 test on the cobas® 4800 System.
• Total Samples Tested (across both CT & NG analyses, including prospective and archived): 17,169

Data Provenance:

• Geographic Origin: 9 geographically diverse sites in the US.
• Retrospective/Prospective: Primarily prospective data collection. Some female NG archived specimens were used, which were "archived prospectively collected" from a previous study.

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

The ground truth was established using a Patient Infected Status (PIS) algorithm, which relied on the results of multiple FDA-cleared NAATs (Nucleic Acid Amplification Tests) rather than human expert interpretation of images or clinical findings directly.

• Number of "Experts" (for constructing ground truth):
  • For females: A combination of results from 2 commercially available FDA-cleared NAATs.
  • For males: A combination of results from 3 commercially available FDA-cleared NAATs.
• Qualifications of "Experts": The "experts" in this context are the FDA-cleared NAATs themselves, which are established diagnostic tests for CT/NG. The text does not mention human experts delineating ground truth for individual cases.

4. Adjudication Method for the Test Set

The adjudication method was a Patient Infected Status (PIS) algorithm based on the concordance of results from multiple FDA-cleared NAATs.

• For females:
  • Infected: One or more positive results in each of the two NAATs. A scenario where one NAAT is positive/negative and the other is positive/positive also leads to "Infected".
  • Not Infected: Varied combinations of negative results or discordant results between the two NAATs, where the majority are negative.
  • Indeterminate: If one or more sample types are invalid for the NAATs, or if there are discordant results with invalid/missing data, the PIS is indeterminate.
• For males:
  • Infected/Not Infected: At least 2 out of the 3 test results must be concordant positive or negative, respectively.
  • Indeterminate: If one test result is invalid/missing and the other two are discordant, or if 2 or 3 test results are invalid/missing, the PIS is indeterminate.

This method essentially acts as a "majority vote" or expert consensus (of diagnostic tests) ground truth.

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 explicitly performed or described in the provided text. This study focuses on the diagnostic accuracy of the device compared to a composite reference standard (PIS), not on how human readers' performance might improve with the AI (an in vitro diagnostic device) as an aid.

Effect Size: N/A (since an MRMC study was not described)

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

Yes, the study describes the standalone performance of the cobas® CT/NG system. The device is referred to as an "automated, qualitative in vitro nucleic acid diagnostic test" that uses real-time PCR. It directly detects CT/NG DNA, and the system software "assigns test results for all tests as positive, negative or invalid." This clearly indicates an algorithm-only standalone performance evaluation.

7. The Type of Ground Truth Used

The type of ground truth used was a composite reference standard known as Patient Infected Status (PIS).

• This PIS was determined by a combination of results from multiple FDA-cleared NAATs.
• Therefore, the ground truth is based on a consensus of highly accurate molecular diagnostic tests, which is a form of expert consensus (where the "experts" are established diagnostic technologies). It is not based on pathology reports, simple expert visual review, or patient outcomes data directly.

8. The Sample Size for the Training Set

The document does not provide information regarding a specific "training set" sample size. This is typical for a diagnostic device undergoing FDA clearance, where the focus is on validation against an independent test set rather than reporting on the development (training) phase of an AI or algorithm. The device is a PCR-based test, which generally involves laboratory optimization and locked-down algorithms rather than iterative machine learning training sets in the same way an image-based AI would.

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

As no specific training set and its associated ground truth establishment were described in this document, this information is not available / not applicable based on the provided text.

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The Xpert CT/NG Assay, performed on the GeneXpert Instrument Systems, is a qualitative in vitro real-time PCR test for the automated detection and differentiation of genomic DNA from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) to aid in the diagnosis of chlamydial and gonorrheal urogenital disease. The assay may be used to test the following specimens from asymptomatic individuals: female and male urine, endocervical swab, and patient-collected vaginal swab (collected in a clinical setting).

Ancillary Collection Kits:

Xpert Vaginal/Endocervical Specimen Collection Kit

The Cepheid Xpert Vaginal/Endocervical Specimen Collection Kit is designed to collect, preserve, and transport Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis DNA in endocervical swab specimens (collected by a clinician) and patient-collected vaginal swab specimens (collected in a clinical setting) from symptomatic and asymptomatic women prior to analysis with the Xpert CT/NG Assay and the Xpert TV Assay.

Xpert Urine Specimen Collection Kit

The Cepheid Xpert Urine Specimen Collection Kit is designed to preserve and transport Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis DNA in first-catch female and male urine specimens from symptomatic and asymptomatic individuals prior to analysis with the Xpert CT/NG Assay and the Xpert TV Assay.

The Xpert CT/NG Assay is a rapid, automated in vitro diagnostic test for qualitative detection and differentiation of DNA from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG). The assay is performed on the Cepheid GeneXpert Instrument Systems. The Xpert CT/NG Assay on the GeneXpert Instrument System automates and integrates sample purification, nucleic acid amplification and detection of the target sequences in simple or complex samples using real-time PCR. The system consists of an instrument, personal computer, and preloaded software for running the tests and viewing the results. The system requires the use of single-use disposable cartridges that hold the PCR reagents and host the PCR process. Because the cartridges are self-contained, crosscontamination between samples is minimized.

The Xpert CT/NG Assay includes reagents for the detection and differentiation of CT and NG. A Sample Processing Control (SPC), a Sample Adequacy Control (SAC), and a Probe Check Control (PCC) are also included. The SPC is present to control for adequate processing of the target bacteria and to monitor the presence of inhibitors in the PCR reaction. The SAC reagents detect the presence of a single copy human gene and monitor whether the specimen contains human cells. The PCC verifies reagent rehydration, PCR tube filling in the cartridge, probe integrity, and dye stability.

The GeneXpert Instrument Systems, comprised of the GeneXpert Dx Systems, the GeneXpert Infinity-48 System and the GeneXpert Infinity-80 System, have 1 to 80 randomly accessible modules, depending upon the instrument, that are each capable of performing separate sample preparation and real-time PCR tests. Each module contains a syringe drive for dispensing fluids (i.e., the syringe drive activates the plunger that works in concert with the rotary valve in the cartridge to move fluids between chambers), an ultrasonic horn for lysing cells or spores, and a proprietary I-CORE® thermocycler for performing real-time PCR and detection.

The ancillary specimen collection kits for use with the Xpert CT/NG Assay are the Cepheid® Xpert® Vaginal/Endocervical Specimen Collection kit and the Cepheid® Xpert® Urine Specimen Collection kit.

The provided text describes a 510(k) premarket notification for the Xpert CT/NG Assay, a qualitative in vitro real-time PCR test for the detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG). This submission is primarily to support the removal of a limitation statement regarding the device's performance in pregnant women, building upon a previously cleared predicate device (K121710).

It's important to note that this document does not describe an AI/ML-based device. It is a molecular diagnostic test. Therefore, many of the requested criteria related to AI/ML device validation (e.g., number of experts for ground truth, MRMC study, training set details) are not applicable to this type of medical device submission.

However, I can extract the relevant information regarding performance criteria and the study conducted to support the change in the intended use.

Here's the breakdown based on the provided document:

Acceptance Criteria and Reported Device Performance

The "acceptance criteria" for this type of submission are typically demonstrating substantial equivalence to a predicate device and showing that the device performs as intended for its specified use. In this specific case, the main goal was to re-evaluate the device's performance in pregnant women to remove a previous limitation.

Since this is a diagnostic test and not an AI/ML device, the performance is typically measured by sensitivity and specificity against a confirmed ground truth, or by demonstrating equivalent performance to a legally marketed predicate device. The document refers back to the original 510(k) (K121710) for most of the detailed analytical and clinical performance characteristics, as the core technology of the device itself has not changed.

Table of Acceptance Criteria and Reported Device Performance (as inferred from the context of a 510(k) for a diagnostic test, particularly the focus within this document):

Note: For a molecular diagnostic test like this, the "acceptance criteria" are usually based on assay validation metrics (e.g., LOD, inclusivity, exclusivity, clinical agreement with a reference method) that would have been established in the predicate device's clearance. This submission focuses on a specific clinical population.

Study Details:

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

   • Test Set Sample Size: The document states "Reanalysis of the clinical data from 510(k) #K121710 was performed for the specimens collected from women who were pregnant at the time of collection." The exact number of pregnant women's specimens re-analyzed is not provided in this document but would be found in the K121710 submission details.
   • Data Provenance: The data comes from the original clinical study conducted for the predicate device (K121710). The document does not specify the country of origin, nor whether the original study was retrospective or prospective, but clinical studies for FDA clearance are typically prospective.

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

   • Not Applicable in the traditional sense for a PCR test. Ground truth for diagnostic tests like this is typically established by:
     • Reference standard methods: Usually a combination of culture, a highly sensitive and specific laboratory-developed test (LDT), or another gold standard for detecting the bacterial DNA/organism.
     • Discrepancy resolution algorithms: In many PCR studies, samples that show discordant results between the investigational device and a comparator method are further tested by a third, highly reliable method (e.g., an in-house PCR with different targets, sequencing).
   • The document does not specify the ground truth method or expert involvement in establishing it, as it refers back to the K121710 submission.

3. Adjudication method for the test set:

   • Not Applicable in the traditional sense of human reader adjudication. For molecular diagnostic tests, ground truth is established by laboratory methods, not by human interpretation of images. Discrepancy resolution for discordant results between methods is a common practice, but it's not "adjudication" by experts in the context of image interpretation. The document doesn't detail this process for the K121710 data reanalysis.

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:

   • Not Applicable. This is a molecular diagnostic test (PCR), not an AI-assisted imaging device. Human readers are not involved in interpreting results in the way they would be with an AI device for radiology, for example.

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

   • Partially Applicable / This is a Standalone Device. The Xpert CT/NG Assay is a fully automated, standalone in vitro diagnostic device. It performs sample purification, nucleic acid amplification, and detection without human intervention in the assay process itself. The "performance" is the direct output of the instrument.

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

   • Likely a composite reference standard or culture/validated PCR. For sexually transmitted infections (STIs) detected via nucleic acid amplification tests (NAATs), the ground truth is typically established by using a combination of other highly sensitive and specific laboratory methods (e.g., another validated NAAT, potentially culture for NG, or a rigorous discrepancy resolution algorithm). The document refers to the original K121710 for details.

7. The sample size for the training set:

   • Not Applicable / No separate "training set" for an AI/ML model. For a molecular diagnostic test, there isn't a "training set" in the sense of an AI model. The assay's performance characteristics (e.g., primer design, probe specificity, assay conditions) are optimized during development and then validated using analytical and clinical studies. The data from K121710 was likely used as a "test set" for performance evaluation, not for training a model.

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

   • Not Applicable. (As there is no "training set" for an AI/ML model here). The ground truth for the clinical validation would have been established using the accepted reference methods for CT/NG detection, as described in point 6.

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The cobas® CT/NG v2.0 Test is an automated, in vitro amplification test for the qualitative detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) DNA in urogenital specimens. The Test utilizes the Polymerase Chain Reaction (PCR) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae DNA in male and female urine, self-collected vaginal swab specimens (collected in a clinical setting), clinician-collected vaginal swab specimens, and endocervical swab specimens, all collected in cobas® PCR Media (Roche Molecular Systems, Inc.), and cervical specimens collected in PreservCyte solution. This test is intended as an aid in the diagnosis of chlamydial and gonococcal disease in both symptomatic and asymptomatic individuals.

The cobas® CT/NG v2.0 Test is an automated, in vitro amplification test for the qualitative detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) DNA in urogenital specimens. The Test utilizes the Polymerase Chain Reaction (PCR) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae DNA in male and female urine, self-collected vaginal swab specimens (collected in a clinical setting), clinician-collected vaginal swab specimens, and endocervical swab specimens, all collected in cobas® PCR Media (Roche Molecular Systems,, Inc.), and cervical specimens collected in PreservCvt® solution. The Test comprises of the assay and ancillary collection kits: (a) for female endocervical and vaginal swabs, and (b) for urine.

The changes to the previously cleared cobas® CT/NG v2.0 Test are limited to the modification of the original cobas® PCR Female Swab Sample Kit (now the cobas® PCR Media Dual Swab Sample Kit) to include one flocked endocervical swab and one spun bud swab, instead of two spun bud swabs. All the supporting clinical and analytical performance data, including stability data for specimens stabilized in the cobas® PCR Media, may be found under K132270. Additional data was generated, as described in Section 4 below, to demonstrate the substantial equivalence of the modified device to its predicate.

The modified cobas PCR Media Dual Swab Sample Kit is comprised of a collection medium tube and a packet containing two sterile swabs.

Kit Composition:

• cobas® PCR Media Dual Swab Sample Kit (1 spun bud swab and 1 flocked bud . swab)
• cobas® PCR Media 1 x 4.3 mL ●

Here's a breakdown of the acceptance criteria and the study details for the cobas® CT/NG v2.0 Test, based on the provided document:

1. Table of Acceptance Criteria and Reported Device Performance

The document focuses on demonstrating substantial equivalence to a predicate device (cobas® CT/NG v2.0 Test, K132270) rather than setting distinct, quantitative acceptance criteria for this specific submission (K163184). The changes in this submission are limited to the swab component of the collection kit. Therefore, the "acceptance criteria" here are implied to be non-inferiority or equivalent performance compared to the predicate device with its original swab.

• CT (Chlamydia trachomatis): PPA (Positive Percent Agreement) point estimate: 94.3%; NPA (Negative Percent Agreement): 99.7%; OPA (Overall Percent Agreement): 99.4%.
• NG (Neisseria gonorrhoeae): The 95% confidence interval for NG PPA encompasses 95%. (Specific point estimate not provided for NG PPA, but the statement implies acceptable performance relative to the predicate).
• Further statistical analyses of Ct values for positive concordant results demonstrated that specimens collected with the flocked swab are not significantly different from specimens collected with the woven swab. |
  | Similar Technological Characteristics (for the assay itself) | The Intended Use, Sample Type, PCR Media, PCR Media Volume, Swab Number, Fiber Composition, and Shaft Composition of the submitted device are identical to the predicate device. The only differences are in Swab Type (1 Spun Bud and 1 Flocked Bud vs. 2 Spun Bud) and Bud Size (5.6 mm Diameter (Spun), 2.9 mm Diameter (Flocked) vs. 5.6 mm Diameter) due to the change in the collection kit. |

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

• Sample Size for Test Set: Not explicitly stated as a single number.
  • For the limiting dilution LoD study, it involved "limiting dilutions of specimens."
  • For the correlation study with clinical specimens, the percentages (PPA, NPA, OPA) imply a number of clinical samples were tested, but the exact count is not provided in this summary. It states "clinical specimens" without further detail on quantity or characteristics beyond being co-collected.
• Data Provenance: Not explicitly stated. The document indicates "clinical specimens," suggesting real-world samples, but doesn't specify country of origin, whether it was retrospective or prospective, or patient demographics.

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

• This information is not provided in the summary. For an in vitro diagnostic device detecting microbial DNA, the "ground truth" is typically established by comparative methods (e.g., another FDA-cleared or well-validated NAAT, laboratory culture, or a composite reference standard) rather than human expert consensus on visual/imaging data.

4. Adjudication Method for the Test Set

• This information is not provided. Given the nature of a DNA amplification test, adjudication methods common in imaging (e.g., 2+1, 3+1) are usually not applicable. Ground truth for diagnostic tests often relies on predefined reference methods.

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

• No, an MRMC comparative effectiveness study was not done. This type of study is primarily relevant for devices where human interpretation plays a significant role (e.g., medical imaging AI tools). The cobas® CT/NG v2.0 Test is an automated in vitro diagnostic device, where the result is determined by the instrument's detection of DNA, not human readers.

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

• Yes, the performance described is inherently standalone. The cobas® CT/NG v2.0 Test is an automated system for qualitative detection of DNA. The reported performance refers to the device's ability to detect CT/NG DNA in specimens using its PCR-based algorithm. There is no "human-in-the-loop" aspect to the DNA detection process itself.

7. The Type of Ground Truth Used

• The summary mentions "clinical specimens" and "limiting dilutions of specimens." For a diagnostic test, the ground truth for clinical performance is typically established by comparing the device's results to a composite reference standard (CRS) or a well-established, highly sensitive, and specific laboratory gold standard method (e.g., another CDC-validated NAAT or culture for NG) applied to the same or split clinical samples. The "PPA," "NPA," and "OPA" values are derived by comparing the test results against such a reference. The details of this gold standard are not explicitly described in this summary but would be present in the full submission (K132270) which underlies the "predicate device" performance.

8. The Sample Size for the Training Set

• This information is not provided in the K163184 summary. As this submission is primarily about a change in a collection component to an already cleared and trained device (cobas® CT/NG v2.0 Test K132270), the focus is on demonstrating non-inferiority with the new component, not new algorithm development or training. The original training data for K132270 would have been much larger.

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

• This information is not provided in the K163184 summary. This would refer to how the original device (K132270) was developed and validated. Typically, for PCR-based in vitro diagnostics, the "training" involves optimizing primers, probes, and reaction conditions using well-characterized samples (often seeded with known quantities of target DNA) and comparing them against established reference methods for positive and negative controls.

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The BD ProbeTec Neisseria gonorrhoeae (GC) Q* Amplified DNA Assay, when tested with either the BD Viper™ System in Extracted Mode or the BD Viper™ LT System, uses Strand Displacement Amplification technology for the direct, qualitative detection of Neisseria gonorrhoeae DNA in clinician-collected female endocervical and male urethral swab specimens, patient-collected vaginal swab specimens (in a clinical setting), and male and female urine specimens (both UPT and Neat). The assay is also intended for use with gynecological specimens collected in BD SurePath™ Preservative Fluid or PreservCyt™ Solution using an aliquot that is removed prior to processing for either the BD SurePath or ThinPrep™ Pap test. The assay is indicated for use with asymptomatic and symptomatic individuals to aid in the diagnosis of gonococcal urogenital disease.

The BD ProbeTec GCO Assay is based on the simultaneous amplification and detection of target DNA using amplification primers and a fluorescently-labeled detector probe The reagents for strand displacement amplification (SDA) are dried in two separate disposable microwells: the Priming Microwell contains the amplification primers, fluorescently-labeled detector probe, nucleotides and other reagents necessary for amplification, while the Amplification Microwell contains the two enzymes (a DNA polymerase and a restriction endonuclease) that are required for SDA. In alignment with the FDA Guidance Document, "Assay Migration Studies for In Vitro Diagnostic Devices, Guidance for Industry and FDA Staff", April 25, 2013 the BD ProbeTec GCQ Assay is being migrated from the existing BD Viper System operating in extracted mode (Viper XTR) to the new BD Viper LT System.

The BD Viper LT System is a table-top instrument that is designed to be fully contained on a standard laboratory bench-top. The system performs automated extraction of nucleic acids from multiple specimen types in addition to amplification and detection of target nucleic acid sequences when utilized with legally marketed in vitro diagnostic assays.

Here's a summary of the acceptance criteria and study details for the BD ProbeTec™ Neisseria gonorrhoeae (GC) Q* Amplified DNA Assay on the BD Viper LT System, based on the provided text:

Acceptance Criteria and Device Performance

The general acceptance criteria for this type of diagnostic device is that the performance on the new system (BD Viper LT) should be substantially equivalent to the predicate device (BD Viper System in Extracted Mode), which implies comparable Positive Percent Agreement (PPA) and Negative Percent Agreement (NPA). While explicit numerical acceptance criteria for PPA and NPA are not stated in the document, the clinical study results are presented to demonstrate this equivalence. The analytical performance (system contamination rate and reproducibility) also contributes to the overall equivalence determination.

• Female (All specimen types): 97.9% (320/327) with 95% CI (95.1%, 100.0%)
• Male (Q*UPT): 100.0% (120/120)
• Overall (All): 98.4% (440/447) with 95% CI (96.4%, 100.0%)

Negative Percent Agreement (NPA):

• Female (All specimen types): 98.8% (934/945) with 95% CI (97.9%, 99.6%)
• Male (Q*UPT): 99.5% (218/219) with 95% CI (98.6%, 100.0%)
• Overall (All): 99.0% (1152/1164) with 95% CI (98.1%, 99.6%) |
  | Analytical Performance | System Contamination Rate:
• Q* Swab Diluent: 0.32% (2/630)
• LBC Specimen Matrix: 0.0% (0/630)

Reproducibility (Overall for various specimen types and panels):

• LBC: % Correct between 20.8% (High Negative) and 100.0% (Negative, Low Positive, Moderate Positive)
• Swab: % Correct between 13.5% (High Negative) and 100.0% (Negative, Low Positive, Moderate Positive)
• UPT: % Correct between 18.8% (High Negative) and 100.0% (Negative, Low Positive, Moderate Positive)
• Overall %CVs range from 9.1% to 433.8% (for negative/high negative where the mean is very low and thus %CV can be high) for quantitation, but 100% agreement for positive controls. |

Study Details

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

   • Clinical Performance Test Set:
     • Female subjects: 617 compliant subjects
     • Male subjects: 167 compliant subjects
     • Total Clinical Samples: A total of 327 positive and 945 negative results for females across various specimen types were evaluated on the BD Viper LT system. For males, 120 positive and 219 negative results were evaluated for Q*UPT.
     • Data Provenance: The specimens were collected prospectively from individuals attending OB/GYN, sexually transmitted disease (STD), and family planning clinics at four geographically diverse clinical sites in North America. These were then assembled into comparison panels at BD and shipped to test sites.
   • Analytical Performance Test Set:
     • System Contamination: 630 Negative samples (Q* Swab Diluent or LBC Specimen Matrix) and 630 Positive samples (spike GC at 10^3 CT EB/mL) per matrix type (Q* Swab Diluent, LBC Specimen Matrix). Tested on three BD Viper LT Systems.
     • Reproducibility: 3 levels of CT and GC organisms (and negative controls) seeded into LBC specimen matrix, vaginal matrix in Q* Swab Diluent, and urine specimen matrix. Two operators per site ran one panel each day for 8 days, totaling 16 runs. Each run consisted of 8 LBC, 8 swab, and 8 UPT panel members. This means for each panel type (LBC, Swab, UPT) and each level (Negative, High Negative, Low Positive, Moderate Positive), there were 96 replicates (3 sites * 2 operators * 8 days * 2 replicates per panel member or 3 sites * 16 runs * 2 replicates per panel member).

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
   The ground truth for the clinical performance study was established by the BD Viper System in extracted mode reference results (the predicate device). It's not explicitly stated that human experts were involved in establishing the ground truth for each individual case in the test set. Instead, the predicate device itself served as the reference standard for comparison. The document does not specify the number or qualifications of experts directly used to establish this "ground truth" beyond relying on the previously cleared predicate device.

3. Adjudication method for the test set:
   The document states: "Each comparison panel consisted of randomly chosen positive and negative specimens (based on BD Viper System in extracted mode reference results). The positive and negative specimens were randomized within the panel, and labeled such that the instrument user was blinded to the specimen results." This implies that the results from the BD Viper LT System were compared against the established reference results from the predicate BD Viper System. There is no mention of a human expert adjudication method (e.g., 2+1, 3+1) for discordant results between the new device and the predicate device. The comparison appears to be direct.

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, a multi-reader multi-case (MRMC) comparative effectiveness study was not done. This device is a molecular diagnostic assay (NAAT) for the detection of Neisseria gonorrhoeae DNA, not an imaging device requiring human reader interpretation. Therefore, the concept of "human readers improving with AI vs without AI assistance" is not applicable in this context. The assay provides a qualitative "positive" or "negative" result.

5. If a standalone (i.e. algorithm only without human-in-the loop performance) was done:
   Yes, the device's performance is standalone. The BD ProbeTec GCQ Assay on the BD Viper LT System is an automated instrument that performs nucleic acid extraction, amplification, and detection. It provides a qualitative result ("positive" or "negative") directly. Human involvement is in specimen collection, loading the samples, and interpreting the final automated result from the instrument, but not in the analytical process of generating the result itself. The clinical performance study directly compares the results of this automated system to the predicate automated system.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc):
   The ground truth for the clinical performance comparison was the results from the predicate device: the BD ProbeTec GCQ Assay on the BD Viper System in Extracted Mode. This type of ground truth is often referred to as a "reference method" or "comparator method" in device migration studies. While the predicate device itself would have initially been cleared against a gold standard (e.g., culture or a combination of clinical outcomes and other diagnostic tests), for this 510(k) submission, the predicate device serves as the established "truth" for demonstrating substantial equivalence of the new system for the same assay.

7. The sample size for the training set:
   The document does not explicitly state the sample size used for a "training set." This submission focuses on the migration of an existing assay formulation to a new instrument system. The assay formulation itself has "not changed." Therefore, it is implied that the assay was developed and "trained" (in a molecular biology sense, not necessarily machine learning) prior to this study on the new platform. The data provided are for analytical verification and a clinical comparison study.

8. How the ground truth for the training set was established:
   As there is no distinct "training set" described in the context of machine learning, the concept of establishing ground truth for it is not applicable here. The assay formulation itself was developed based on established molecular biology principles for detecting Neisseria gonorrhoeae DNA. The ground truth for the predicate device (K081825) would have been established through its own clinical trials, likely using culture as a primary reference standard, possibly augmented by discrepant analysis with other methods. For this K140448 submission, the primary ground truth for comparison is the performance of the predicate device itself.

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The Abbott RealTime CT/NG assay is an in vitro polymerase chain reaction (PCR) assay for the direct, qualitative detection of the plasmid DNA of Chlamydia trachomatis and the genomic DNA of Neisseria gonorthoeae. The assay may be used to test the following specimens from symptomatic individuals: female endocervical swab, clinician-collected vaginal swab, and patient-collected vaginal swab specimens; male urethral swab specimens; and female and male urine specimens. The assay may be used to test the following specimens from asymptomatic individuals: clinician-collected vaginal swab and patient-collected vaginal swab specimens; female and male urine specimens.

The Abbott multi-Collect Specimen Collection Kit is intended for the collection and transportation of male and female swab and urine specimens for the detection of Chlamydia trachomatis and Neisseria gonorrheae per instructions provided. Refer to the specimen collection procedure in the package insert for specimen collection instructions for specific sample types.

Self-collected vaginal swab specimens are an option for screening women when a pelvic exam is not otherwise indicated. The Abbott multi-Collect Specimen Collection Kit is not intended for home use.

The Abbott multi-Collect Specimen Collection Kit can be used to collect either a swab or a urine specimen. Each Abbott multi -Collect Specimen Collection Kit contains:

• . One capped Transport Tube containing 1.2 mL Specimen Transport Buffer
• . One Individually Packaged Sterile Specimen Collection Swab
• . One disposable transfer pipette.

The Specimen Transport Buffer is used to stabilize DNA until sample preparation. The individually packaged sterile Specimen Collection Swab is used for swab sample collection and placed directly into the Transport Tube. The transfer pipette is used to add approximately 3 mL of urine to the Transport Tube. The Abbott multi -Collect Specimen Collection Kit is for single use only.

The Abbott multi-Collect Specimen Collection Kit Swab is approximately 14 cm in length with a polyester fiber tip. The swab shaft has a polystyrene solid core that is orange in color. The swab has a molded score completely around the shaft, between 7.86 cm and 7.89 cm from the swab tip, to provide a clean break-point. The polyesterfiber swab tip is approximately 1.3 cm in length and less than 3.28 mm in diameter.

This document describes the regulatory submission for a modification to the Abbott multi-Collect Specimen Collection Kit, specifically a change in the swab fiber component. The submission focuses on demonstrating that the new swab is substantially equivalent to the previously cleared swab and does not impact the performance of the Abbott RealTime CT/NG assay.

1. Table of Acceptance Criteria and Reported Device Performance

The submission doesn't explicitly state "acceptance criteria" in a numerical, threshold-based format. Instead, the studies demonstrate performance relative to the existing device and expected assay performance (e.g., detection rates approaching 100% for low positive samples). The goal of these studies is to confirm that the new swab material does not negatively impact the assay's performance.

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

• Biocompatibility: The specific sample sizes for cytotoxicity, irritation, and sensitization tests are not provided in the summary.
• 90-Day Specimen Stability: Not explicitly stated, but involved testing "simulated high and low positive swab specimens."
• Sample Freeze-Thaw Stability: 90 CT analyte samples and 90 NG analyte samples (total 180 samples) were tested.
• LOD Confirmation: 234 samples were tested for both CT and NG.
• Reproducibility: 189 replicates were tested for each panel member. There were 4 panel members (3 concentrations + 1 negative) for each analyte (CT and NG). This suggests a total of 189 replicates/panel member * 4 panel members * 2 analytes = 1512 individual tests for quantification, or more accurately, 189 replicates per panel member across the different conditions. Seven replicates of each panel member were tested in each run, with nine runs performed across three m2000 instrument systems.
• Accelerated Stressed Swab Stability: Not explicitly stated, but involved "testing simulated low positive swab specimens containing a target concentration of 320 copies of CT and 320 copies of NG in each 400 uL sample preparation input volume."
• Provenance: All data appears to be retrospective experimental data generated in a laboratory setting using simulated specimens rather than prospective clinical samples. The country of origin of the data is not explicitly stated but is implicitly associated with Abbott Molecular Inc. in the USA.

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

No human experts were used to establish the "ground truth" in these studies. The studies are analytical performance studies, not clinical studies involving patient diagnoses. The "ground truth" (e.g., presence and concentration of CT/NG DNA) was established by spiking known concentrations of target analytes into simulated specimens in a laboratory setting.

4. Adjudication Method for the Test Set

Not applicable. As described above, the ground truth was established by precise laboratory spiking of analytes, not by expert consensus or clinical adjudication.

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

No. This is not an MRMC study. The device is a specimen collection kit the performance of which is measured using an in vitro assay (Abbott RealTime CT/NG assay). There are no human readers or interpretation involved in the performance evaluation of the collection device itself. The studies focus on the analytical performance of the kit to collect and preserve DNA for subsequent automated testing.

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

Yes, this is an algorithm-only (assay-only) performance evaluation. The "device" being evaluated is the Abbott multi-Collect Specimen Collection Kit, specifically its swab component. Its performance is assessed by how effectively it allows the Abbott RealTime CT/NG assay (an automated PCR assay) to detect targets. Therefore, the performance demonstrated is that of the collection kit in conjunction with the fully automated assay, without any human interpretation steps directly related to the collection kit's function.

7. The Type of Ground Truth Used

The ground truth used was based on known concentrations of spiked target analytes (DNA for Chlamydia trachomatis and Neisseria gonorrhoeae) in simulated laboratory specimens. This is a form of analytical truth or definitive measurement through controlled experimental design.

8. The Sample Size for the Training Set

These studies are analytical validation studies for a medical device modification (swab component), not a machine learning or AI model development. Therefore, there is no concept of a "training set" in the context of these studies. The experiments described are test/validation studies for the physical collection device.

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

Not applicable, as there was no training set for an AI model.

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The cobas® CT/NG v2.0 Test is an automated, in vitro nucleic acid amplification test for the qualitative detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) DNA in urogenital specimens. The Test utilizes the Polymerase Chain Reaction (PCR) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae DNA in male and female urine, self-collected vaginal swab specimens (collected in a clinical setting), clinician-collected vaginal swab specimens, and endocervical swab specimens, all collected in cobas PCR Media (Roche Molecular Systems, Inc.), and cervical specimens collected in PreservCyt® solution. This test is intended as an aid in the diagnosis of chlamydial and gonococcal disease in both symptomatic and asymptomatic individuals.

The cobas® CT/NG Test is an in vitro nucleic acid amplification test that utilizes the Polymerase Chain Reaction (PCR) and nucleic acid hybridization for the qualitative detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) DNA to aid in the diagnosis of chlamydial and gonococcal disease. The test may be used with vaginal swab specimens self-collected in a clinical setting and male urine from both symptomatic individuals. Specimens to be tested should be collected in cobas® PCR Media.

The cobas® CT/NG Tests for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are based on two major processes: (1) automated sample preparation to obtain nucleic acids, including CT and NG DNA; (2) simultaneous PCR amplification of target DNA sequences using both CT and NG specific complementary primer pairs and real-time detection of cleaved fluorescent-labeled CT and NG specific oligonucleotide detection probes. Internal control, containing CT and NG DNA, is added to all samples during automated sample preparation and is amplified and detected simultaneously with each sample to monitor the entire process.

The cobas® CT/NG Tests utilize the cobas® 4800 System for automated sample preparation and automated amplification and detection. The cobas® 4800 system software integrates the sample preparation with nucleic acid amplification and detection to generate test results.

This platform consists of modular hardware components that are linked by a dedicated network. The major hardware components of the cobas 4800 system are shown in Figure 1:

• cobas x 480 instrument (for automatic sample preparation) .
• cobas z 480 analyzer (for automatic amplification and detection using real-time PCR) t
• Control Unit with cobas® 4800 software .
• Assay reagents .
• (Optional) Communication through a firewall with a Laboratory Information System . (LIS) and/or intranet for LIS and/or telecommunications

This 510(k) submission (K140887) describes software system changes to the cobas® CT/NG v2.0 Test (K132270) and the cobas® CT/NG Test (K110923). The primary purpose of this submission is to demonstrate that migrating these tests to the new cobas® 4800 system software version 2.1 does not adversely affect their performance.

Here's a breakdown of the acceptance criteria and the supporting study:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criterion for this submission is demonstrating that the migration of the cobas® CT/NG Tests to software version 2.1 does not impact the analytical sensitivity (Limit of Detection) of the assays, maintaining equivalence to the predicate devices. This is shown by the overlapping 95% confidence intervals for the Limit of Detection (LOD) between the previous software versions and the new software version 2.1.

Study Proving the Device Meets Acceptance Criteria

The study described is primarily a technical performance verification / regression testing study focused on demonstrating the non-inferiority of the device's analytical sensitivity after the software upgrade.

• Study Name: CT/NG Test Technical Performance Verification (Limit of Detection regression testing)

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

• Sample Size for Test Set: For Limit of Detection (LOD) testing, a total of 10 runs were performed, generating up to 90 replicates for each of six levels for each test (cobas® CT/NG Test for SR1.1 vs SR2.1, and cobas® CT/NG v2.0 Test for SR1.2 vs SR2.1).
• Data Provenance: The document implies that this was prospective testing conducted by Roche Molecular Systems (RMS) in Pleasanton, California for system-level verification and at Roche Diagnostics Ltd. (RDI, Rotkreuz, Switzerland) for component and unit-level testing. The data is from internal studies conducted by the manufacturer. Specific country of origin for the samples is not explicitly stated, but the testing sites are in the US (California) and Switzerland.

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

N/A. This was an analytical performance study (Limit of Detection) assessing the instrument's ability to detect specific analytes at low concentrations. It does not involve human interpretation or a "ground truth" derived from expert consensus on clinical cases. The "ground truth" in this context would be the spiked concentrations of CT and NG, and the device's ability to consistently detect them.

4. Adjudication Method for the Test Set

N/A. As this is an analytical performance study, a clinical adjudication method is not applicable. The device's output (positive/negative detection based on PCR cycle threshold analysis) is compared against pre-defined expected outcomes for spiked concentrations.

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

No. A Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This submission focuses on the analytical performance of an in vitro diagnostic device, specifically verifying that software changes do not alter its established Limit of Detection. MRMC studies are typically used for imaging devices where human readers interpret results, often with and without AI assistance, to measure diagnostic accuracy and reader improvement.

6. Standalone (Algorithm Only) Performance Study

Yes, in essence. The Limit of Detection (LOD) regression testing specifically evaluates the performance of the algorithm and instrument system itself (the combined cobas® 4800 System and the CT/NG Tests with the new software) by measuring its ability to detect specific concentrations of CT and NG. While not explicitly termed a "standalone" study in the context of clinical diagnostic accuracy, it represents the algorithm's performance without human intervention in the interpretation of the raw signal data, as the software processes raw fluorescence data using data analysis algorithms and determines validity and outputs results (Section {6}).

7. Type of Ground Truth Used

The ground truth used was analytically prepared samples with known concentrations of Chlamydia trachomatis (EB/mL) and Neisseria gonorrhoeae (CFU/mL). These samples were spiked at various levels around the expected Limit of Detection. This allowed for the determination of the LOD using Probit analysis.

8. Sample Size for the Training Set

The document does not specify a separate training set sample size. This submission is for a software update to an already cleared device. The focus is on verifying that the changes do not degrade the performance of the established algorithms. Therefore, it's more about re-validation and regression testing rather than developing a new algorithm requiring a distinct training set. The algorithms themselves would have been "trained" during the development of the original predicate devices (K132270 and K110923).

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

As no new algorithm requiring a specific training set is discussed or implied in this submission, the establishment of ground truth for a training set is not applicable. The underlying algorithms for the CT/NG tests were already established and validated in the predicate submissions; this submission verifies their performance is unchanged after a software update to the platform.

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The cobas CT/NG v2.0 Test is an automated, in vitro nucleic acid amplification test for the qualitative detection of Chlamydia trachomatis (CT) and/or Neisseria gonormoeae (NG) DNA in urogenital specimens. The Test utilizes the Polymerase Chain Reaction (PCR) for the detection of Chiamydia trachomatis and Neisseria gonormoeae DNA in male and female urine, self-collected vaginal swab specimens (collected in a clinical setting), clinician-collected vaginal swab specimens, and endocervical swab specimens, all collected in cobas® PCR Media (Roche Molecular Systems, Inc.), and cervical specimens collected in PreservCyt® solution. This test is intended as an aid in the diagnosis of chlamydial and gonococcal disease in both symptomatic and asymptomatic individuals.

The changes between the previously cleared cobas® CT/NG Test (K110923) and the currently submitted cobas® CTNG v2.0 Test are limited to the modification of the sample preparation workflow which requires a system software update related to the cobas 4800 system. There are no changes for the reagents or the design between the cobas® CT/NG v2.0 Test and the cobas® CT/NG Test. The Roche Molecular Systems (RMS) cobas® CT/NG v2.0 Test consists of six reagent kits:

• cobas® 4800 System Sample Preparation Kit .
• cobas 4800 CT/NG v2.0 Amplification/Detection Kit .
• cobas® 4800 CT/NG Controls Kit .
• cobas 4800 System Wash Buffer Kit .
• cobas® 4800 System Control Diluent Kit .
• cobas® 4800 System Liquid Cytology Preparation Kit .

Sample Collection Kits to be used for the cobas CT/NG v2.0 Test are:

• cobas® PCR Female Swab Sample Kit •
• cobas® PCR Urine Sample Kit .
• PreservCyt® (Hologic, Inc.) .

The cobas® CTNG v2.0 Test for Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) is based on two major processes: (1) automated sample preparation to obtain nucleic acids, including CT and NG DNA; (2) simultaneous PCR amplification of target DNA sequences using both CT and NG specific complementary primer pairs and real-time detection of cleaved fluorescent-labeled CT and NG specific oligonucleotide detection probes. Internal control. containing CT and NG DNA. is added to all samples during automated sample preparation and is amplified and detected simultaneously with each sample to monitor the entire process.

The cobas 4800 System utilizes the cobas x 480 Instrument for automated sample preparation, and the cobas z 480 Analyzer for automated amplification and detection. The cobas® 4800 system software integrates the sample preparation with nucleic acid amplification and detection to generate test results.

Here's a breakdown of the acceptance criteria and study details for the cobas® CT/NG v2.0 Test, based on the provided 510(k) summary:

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria are implied by the reported performance metrics, primarily sensitivity and specificity, at various specimen types and symptom statuses. The device generally aims for high sensitivity and specificity.

Chlamydia trachomatis (CT) Clinical Performance

Neisseria gonorrhoeae (NG) Clinical Performance

2. Sample Size for the Test Set and Data Provenance

• Total Evaluable Subjects: 6,004 (5,266 females and 738 males)

• Female Test Set Sub-samples:

  • Endocervical Swabs (SW): 2926 (1932 symptomatic, 994 asymptomatic)
  • Urine (UR): 2945 (1937 symptomatic, 1008 asymptomatic)
  • Clinician-collected Vaginal Swabs (VG-C): 1902 (899 symptomatic, 1003 asymptomatic)
  • Self-collected Vaginal Swabs (VG-S): 2037 (1041 symptomatic, 996 asymptomatic)
  • PreservCyt (PC Pre): 2937 (1935 symptomatic, 1002 asymptomatic)
  • PreservCyt (PC Post): 2878 (1871 symptomatic, 1007 asymptomatic)

• Male Test Set Sub-samples:

  • Urine (UR): 738 (278 symptomatic, 460 asymptomatic)

• Data Provenance: The studies were multi-center clinical investigations conducted in the United States.

  • One clinical investigation used archived samples (endocervical specimens, self-collected and clinician collected vaginal specimens, endocervical specimens in PreservCyt Solution, and male and female urine specimens, from symptomatic and asymptomatic males and females) from the previous cobas® CT/NG Test evaluation.
  • A second investigation used prospectively collected fresh samples (endocervical specimens, clinician-collected vaginal specimens, female urine specimens, and cervical specimens in PreservCyt Solution from asymptomatic women).
  • Specimen collection took place at 18 collection sites in the US, including family planning, Obstetrics/Gynecology (OB/GYN) clinics, and sexually transmitted disease clinics.

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. The ground truth ("Patient Infected Status" - PIS) was established using a combination of results from two commercially available nucleic acid amplification tests (NAATs) (NAAT1 and NAAT2). These reference NAATs are implicitly considered the "expert" or gold standard. The qualifications of personnel performing these reference NAATs are not specified.

4. Adjudication Method for the Test Set

The adjudication method for establishing Patient Infected Status (PIS) was based on a "2+1" or consensus approach using two reference NAATs.

• A subject was categorized as infected for CT or NG if a minimum of two positive results (at least one from each reference NAAT) was reported.
• For CT only, female subjects with positive results on both reference urine specimens and negative results on both reference endocervical swab specimens and the reference cervical sample were categorized as infected for urine and not infected for swab specimens.
• A subject was classified as non-infected if at least one of the reference NAATs reported negative results for all sample types.
• Subjects were excluded if PIS could not be determined due to missing/indeterminate results from reference tests.

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 focuses on the standalone performance of the device (a diagnostic test kit), not on human reader performance with or without AI assistance. Therefore, there is no effect size of human readers improving with AI.

6. If a Standalone Study was done

Yes, a standalone performance study (algorithm only without human-in-the-loop performance) was done. The entire clinical performance section (Section 5) evaluates the cobas® CT/NG v2.0 Test directly against the established Patient Infected Status (PIS), which is derived from other NAATs, representing the algorithm's performance.

7. The Type of Ground Truth Used

The ground truth used was expert consensus (proxy by reference assays), specifically the Patient Infected Status (PIS), determined by the concordance of results from two commercially available predicate/reference Nucleic Acid Amplification Tests (NAATs).

8. The Sample Size for the Training Set

The document does not explicitly state a separate sample size for a training set. The language used ("clinical investigations") suggests that the samples described in Section 5.2 are primarily for performance evaluation and not necessarily a distinct, partitioned training set as might be found in machine learning contexts. However, the study does mention using archived samples from a previous clinical study of the cobas® CT/NG Test (K110923) combined with prospectively collected fresh samples for the current evaluation. It's possible the archived data contributed to various stages of development or internal validation, but a formal "training set" for the v2.0 device as a distinct phase with specified numbers is not detailed in this summary.

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

As a distinct "training set" is not explicitly defined, the method for establishing its ground truth is also not detailed. However, it's reasonable to infer that any data used in the development or internal validation phases would have relied on similar or equivalent methods for ground truth determination, likely involving comparison to established reference methods or culture, as is standard for diagnostic assay development. The summary focuses on the clinical performance evaluation of the final device using the PIS as described in point 4.

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The APTIMA Combo 2 Assay is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection and differentiation of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (GC) to aid in the diagnosis of chlamydial and/or gonococcal urogenital disease using the PANTHER System as specified.

On the PANTHER System, the assay may be used to test the following specimens from symptomatic and asymptomatic individuals: clinician-collected endocervical, vaginal and male urethral swab specimens, clinician-collected gynecological specimens collected in the PreservCyt Solution, patient-collected vaginal swab specimens, and male urine specimens.

Patient-collected vaginal swab specimens are an option for screening women when a pelvic exam is not otherwise indicated. The vaginal swab specimen collection kit is not for home use.

The APTIMA Combo 2 Assay combines the technologies of target capture, transcriptionmediated amplification (TMA), and dual kinetic assay (DKA).

Specimens are collected and transferred into their respective specimen transport tubes. The transport solutions in these tubes release the rRNA targets and protect them from degradation during storage. When the APTIMA Combo 2 Assay is performed in the laboratory, the target rRNA molecules are isolated from specimens by use of capture oligomers via target capture that utilizes magnetic microparticles. The capture oligomers contain sequences complementary to specific regions of the target molecules as well as a string of deox yadenosine residues. A separate capture oligomer is used for each target. During the hybridization step, the sequence specific regions of the capture oligomers bind to specific regions of the target molecules. The capture oligomer:target complex is then captured out of solution by decreasing the temperature of the reaction to room temperature. This temperature reduction allows hybridization to occur between the deoxyadenosine region on the capture oligomer and the poly-deoxythymidine molecules that are covalently attached to the magnetic particles. The microparticles, including the captured target molecules bound to them, are pulled to the side of the reaction vessel using magnets and the supernatant is aspirated. The particles are washed to remove residual specimen matrix that may contain amplification reaction inhibitors. After the target capture steps are completed, the specimens are ready for amplification.

Target amplification assays are based on the ability of complementary oligonucleotide primers to specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The APTIMA Combo 2 Assay replicates a specific region of the 23S rRNA from CT and a specific region of the 16S rRNA from GC via DNA intermediates. A unique set of primers is used for each target molecule. Detection of the rRNA amplification product sequences (amplicon) is achieved using nucleic acid hybridization. Single-stranded chemiluminescent DNA probes, which are complementary to a region of each target amplicon, are labeled with different acridinium ester molecules. The labeled DNA probes combine with amplicon to form stable RNA:DNA hybrids. The Selection Reagent differentiates hybridized from unhybridized probe, eliminating the generation of signal from unhybridized probe. During the detection step, light emitted from the labeled RNA:DNA hybrids is measured as photon signals in a luminometer, and are reported as Relative Light Units (RLU). In DKA, differences in the kinetic profiles of the CT and GC labeled probes allow for the differentiation of signal; kinetic profiles are derived from measurements of photon output during the detection read time. The chemiluminescent detection for CT signal has very rapid kinetics and has the "flasher" kinetic type. The chemiluminescent detection reaction for GC signal is relatively slower and has the "glower" kinetic type. Assay results are determined by a cut-off based on the total RLU and the kinetic curve type.

APTIMA Combo 2® Assay (on PANTHER® System) - Acceptance Criteria and Study Details

The APTIMA Combo 2® Assay is a nucleic acid amplification test for the qualitative detection and differentiation of ribosomal RNA from Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (GC) to aid in the diagnosis of chlamydial and/or gonococcal urogenital disease. This 510(k) submission (K132251) specifically focuses on clearing the assay for use with male urine specimens on the PANTHER System.

1. Acceptance Criteria and Reported Device Performance

The provided document details the performance characteristics for male urine, alongside other specimen types, in terms of sensitivity and specificity based on two clinical studies. While explicit "acceptance criteria" in a numeric format (e.g., minimum sensitivity of X%) are not directly stated, the reported performance metrics demonstrate the device's efficacy across various specimen types and symptom statuses. The regulatory approval implies these performance levels met the FDA's requirements for substantial equivalence.

Reported Device Performance for Male Urine (from Table 4 for CT and Table 7 for GC):

Additional detailed performance by symptom status is provided in Table 5 (CT) and Table 8 (GC) and by individual study in Table 6 (CT) and Table 9 (GC).

2. Sample Sizes and Data Provenance for Test Set

The clinical performance data was derived from two multi-center clinical studies conducted in the United States. The data is prospective, as specimens were collected from enrolled symptomatic and asymptomatic individuals for the purpose of the study.

Test Set Sample Sizes:

• Clinical Study 1: Included male urethral swab, vaginal swab, PreservCyt Solution liquid Pap, female endocervical swab, and male urine samples.
  • Male subjects (urine): 580 enrolled. 580 male urine samples were tested.
  • For CT performance analysis, 1799 male urine samples were included (data from Clinical Study 1 and 2 combined, see Table 4).
  • For GC performance analysis, 1797 male urine samples were included (data from Clinical Study 1 and 2 combined, see Table 7).
• Clinical Study 2: Primarily focused on male urine specimens.
  • Male subjects: 1492 enrolled, 1478 male urine samples from non-withdrawn subjects were tested.
  • For CT performance analysis, 1799 male urine samples were included (data from Clinical Study 1 and 2 combined, see Table 4).
  • For GC performance analysis, 1797 male urine samples were included (data from Clinical Study 1 and 2 combined, see Table 7).

A breakdown of male urine samples by study and symptom status for performance evaluation:

• CT (Table 6):
  • Study 1 Asymptomatic: 323 samples
  • Study 2 Asymptomatic: 979 samples
  • Study 2 Symptomatic: 497 samples
  • Total (Study 1 + Study 2) for male urine (Table 4): 1799 samples
• GC (Table 9):
  • Study 1 Asymptomatic: 320 samples
  • Study 2 Asymptomatic: 980 samples
  • Study 2 Symptomatic: 497 samples
  • Total (Study 1 + Study 2) for male urine (Table 7): 1797 samples

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the number of "experts" used to establish the ground truth or their specific qualifications (e.g., radiologist with X years of experience), as this is a diagnostic assay for infectious disease rather than image-based diagnosis.

Instead, the ground truth ("infected status") was established using cleared nucleic acid amplification tests (NAATs). The reference methods are described as:

• "cleared nucleic acid amplification tests (NAATs)" for Clinical Study 1 (male urethral swab, male and female urine, and PreservCyt Solution liquid Pap samples).
• "cleared NAATs" for Clinical Study 2 (male urethral swab and urine samples). Specifically, the infected status algorithm used "urethral swab and urine sample results from one reference CT and GC NAAT and urine sample results from two additional reference CT and GC NAATs to generate four reference results for each analyte."

The qualifications of the individuals performing these reference NAATs are not specified but would presumably be laboratory professionals trained in molecular diagnostics.

4. Adjudication Method for the Test Set

The adjudication method for establishing the "infected status" (ground truth) for the clinical test set was based on an algorithm using multiple reference NAATs.

• Clinical Study 1: "Subjects were categorized as infected if a positive result occurred in each of the two reference NAATs." (See Tables 10, 11, 13, and 14 for specific algorithms for different specimen types and analytes). For female subjects, if positive NAAT results occurred only in urine, they were considered infected for urine evaluation but non-infected for other non-urine specimens.
• Clinical Study 2 (Male Urine): "Subjects were categorized as infected if a positive result occurred in at least two of the reference NAATs." (See Tables 13 and 15).

This method is a form of "consensus" or "composite comparator" ground truth, where multiple established diagnostic tests are used to determine the true infection status in the absence of a single universally accepted gold standard.

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

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was mentioned or performed. This device is an in vitro diagnostic assay, not an imaging device requiring human reader interpretation or AI assistance for human readers. Therefore, the concept of "human readers improve with AI vs without AI assistance" is not applicable here. The assay provides a qualitative result directly.

6. Standalone (Algorithm Only) Performance

Yes, a standalone performance study was conducted. The performance data presented in the tables (Tables 4, 5, 6, 7, 8, 9) for sensitivity, specificity, PPV, and NPV represent the standalone performance of the APTIMA Combo 2 Assay on the PANTHER System, without human-in-the-loop interpretation being part of the result generation. The device itself performs the detection and differentiation of rRNA and provides a qualitative result.

7. Type of Ground Truth Used

The type of ground truth used was "composite comparator" or "reference NAAT consensus". For both clinical studies, the "infected status" was established by comparing results from two or more FDA-cleared nucleic acid amplification tests (NAATs) performed on the same or corresponding samples, rather than pathology (histology), clinical outcomes data, or a single expert's opinion.

8. Sample Size for the Training Set

The document does not explicitly state a separate "training set" sample size in the context of device development. For in vitro diagnostic devices, "training" often refers to internal analytical studies and optimization during development, rather than a distinct clinical "training set" in the way it's used for AI or machine learning models. The provided clinical studies (Clinical Study 1 and Clinical Study 2) represent the validation or test sets used to establish clinical performance.

Analytical sensitivity (Limit of Detection) studies were conducted using dilutions of CT organisms and GC organisms (7). These analytical studies involve controlled samples to determine the detection limits and would be part of the internal development and analytical verification processes, but are not typically referred to as a "training set" in this context.

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

As noted above, a distinct "training set" with established ground truth in the clinical context is not explicitly described. For the analytical sensitivity studies, the "ground truth" (i.e., known concentration of organisms) was established by spiking known concentrations of CT and GC organisms into various matrices (e.g., Specimen Transport Medium, urine) and testing dilutions. This allows for the determination of the limit of detection (LOD) for the assay.

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