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The GEN-PROBE APTIMA® Assay for Chlamydia trachomatis is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) to aid in the diagnosis of chlamydial urogenital disease using the TIGRIS® DTS® Automated Analyzer or semiautomated instrumentation as specified. The assay may be used to test the following specimens from symptomatic individuals: clinician-collected endocervical, vaginal and 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 endocervical, vaginal and male urethral swab specimens, patient-collected vaginal swab specimens, and female and male urine specimens. The assay is also intended for use with the testing of gynecological specimens, from both symptomatic and asymptomatic patients collected in the PreservCyt® Solution and processed with the Cytyc ThinPrep® 2000 System.

Clearance of this premarket notification extends the clinical performance claims of the commercially available GEN-PROBE®APTIMA® Assay for Chlamydia trachomatis with the testing of gynecological specimens collected in the PreservCyt® Solution and processed with the Cytyc ThinPrep® 2000 System, for use on the TIGRIS® DTS® System. The ancillary kit for this application is commercially available as the GEN-PROBE APTIMA Specimen Transfer Kit. The components of the APTIMA Specimen Transfer Kit include: (1) a transport tube containing transport media with a penetrable cap and (2) specific instructions for ruse regarding decontamination and specimen processing procedures. The APTIMA Transfer Kit may only be used in conjunction with the APTIMA Assays.

Acceptance Criteria and Device Performance for APTIMA® Assay for Chlamydia trachomatis

The APTIMA® Assay for Chlamydia trachomatis (CT) on the TIGRIS® DTS® System extends the clinical performance claims for testing gynecological specimens collected in PreservCyt® Solution and processed with the Cytyc ThinPrep® 2000 System. The study aimed to demonstrate equivalent performance between the previously validated DTS Systems and the TIGRIS DTS System.

1. Table of Acceptance Criteria and Reported Device Performance

• Positive % Agreement: 100% (94.4-100% CI)
• Negative % Agreement: 100% (93.2-100% CI)
• Overall % Agreement: 100% (96.9-100% CI) |
  | Clinical Performance Equivalence (Clinical Panel Study) | The ACT Assay on the TIGRIS System should show 100% agreement with expected CT results for panel members with varying CT rRNA concentrations (including 0 fg/assay and various positive concentrations) in PreservCyt liquid Pap specimens, and demonstrate equivalence to the DTS Systems. | The percent agreement for each level of rRNA in PreservCyt liquid Pap specimens with the expected CT results for both the TIGRIS System and the DTS Systems was 100% for all panel members. The overall % agreement between TIGRIS and DTS was 100% (97.2-100% CI). |

2. Sample Sizes and Data Provenance

• Analytical Sensitivity: 60 replicates of C. trachomatis rRNA spiked into post-processed PreservCyt liquid Pap specimen pool.
• Analytical Specificity: 24 culture isolates tested.
• Specimen-Caused Inhibition: 239 negative clinical post-processed PreservCyt liquid Pap specimens.
• Interference by Whole Blood: Clinical post-processed PreservCyt liquid Pap specimen pools, tested with 0% and 10% whole blood, both unspiked and spiked with CT rRNA.
• Clinical Specimen Study: 116 PreservCyt specimens from female subjects (81 symptomatic, 35 asymptomatic).
• Clinical Panel Study: 5 panel members, including a negative control and 4 positive concentrations of CT rRNA, prepared by spiking. Total of 132 replicates (12 for negative, 30 for each positive concentration).

Data Provenance: The report indicates a "prospective, multi-center clinical study" was conducted for the clinical performance data. Patient enrollment occurred at "family planning, OB/GYN, public health, and STD clinics." This suggests the clinical data is prospective and collected from various clinical sites. The country of origin is not explicitly stated but implied to be the USA given the FDA 510(k) submission.

3. Number of Experts and Qualifications for Ground Truth

The document does not explicitly state the "number of experts" or their specific "qualifications" used to establish ground truth in the traditional sense of expert review for image interpretation or diagnosis.

• For the Clinical Specimen Study, specimens were first screened using "FDA-cleared applications of the APTIMA COMBO 2 (AC2) Assay." The results from this FDA-cleared assay served as the reference standard (ground truth proxy) for comparing the DTS Systems and TIGRIS System results.
• For the Clinical Panel Study, negative PreservCyt specimens were pooled and confirmed negative by testing with the ACT Assay on the DTS Systems. Then, CT ribosomal RNA (rRNA) was spiked at known concentrations to create panel members. The "expected CT results" based on the known spiked concentrations served as the ground truth.

4. Adjudication Method for the Test Set

The document does not describe an adjudication method like 2+1 or 3+1. For the clinical specimen study, the "ground truth" was established by prior testing with an "FDA-cleared" assay (APTIMA COMBO 2 Assay), implying it was considered a reliable reference. Discrepancies, if any, between the test systems (TIGRIS vs. DTS) were analyzed for percent agreement, rather than adjudicated by independent readers. "Specimens with final invalid or equivocal screening results were not selected for testing," suggesting a pre-screening step to ensure data quality.

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

No Multi-Reader Multi-Case (MRMC) comparative effectiveness study was performed as this is an in vitro diagnostic (IVD) assay detection system, not an imaging device requiring human reader interpretation. The study compares the performance of two automated systems (TIGRIS DTS System vs. DTS Systems) for detecting Chlamydia trachomatis. There is no human-in-the-loop component for which an improvement effect size with AI assistance would be relevant.

6. Standalone Performance Study

Yes, a standalone performance study was done for the algorithm (the APTIMA Assay on the TIGRIS DTS System). The entire document describes the analytical and clinical performance of the device on its own, comparing it against a reference standard or a previously cleared device. The "overall % agreement" in the clinical studies directly reflects the standalone performance of the TIGRIS DTS System relative to the DTS system and the expected results.

7. Type of Ground Truth Used

• Analytical Studies (Sensitivity, Specificity, Inhibition, Interference): Ground truth was established by known concentrations of C. trachomatis rRNA or culture isolates, or by the absence of target/interfering substance in controlled laboratory settings.
• Clinical Specimen Study: Ground truth was established by results from a previously FDA-cleared assay (APTIMA COMBO 2 Assay), acting as the reference standard.
• Clinical Panel Study: Ground truth was established by known spiked concentrations of CT ribosomal RNA (rRNA) into confirmed negative PreservCyt specimens.

8. Sample Size for the Training Set

The document describes an analytical validation and clinical performance study for a diagnostic assay, not a machine learning or AI algorithm in the context of a "training set." Therefore, a "training set" as understood in AI/ML development is not applicable here. The assays are based on target amplification nucleic acid probe technology.

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

As explained in point 8, there is no explicit "training set" as this is not an AI/ML device that requires machine learning for its core function. The assay's parameters and cut-offs would have been established during earlier development and validation phases (not detailed in this 510(k) summary), likely using characterized positive and negative samples, similar to the "panel" approach seen in the clinical panel study.

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The APTIMA Assay for Chlamydia trachomatis is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) in clinician-collected endocervical, vaginal and male urethral swab specimens, patient-collected vaginal swab specimens, and female and male urine specimens. The assay is also intended for use with the testing of gynecological specimens collected in the PreservCyt® Solution and processed with the Cytyc ThinPrep® 2000 System. The assay may be used to test specimens from symptomatic and asymptomatic individuals to aid in the diagnosis of chlamydial urogenital disease.

Clearance of this premarket notification extends the clinical performance claims of the commercially available GEN-PROBE APTIMA Assay for Chlamydia trachomatis to include PreservCyt liquid Pap specimens (collected and processed by the Cytyc ThinPrep 2000 Processor) as acceptable testing specimens. The ancillary kit formulated for this specific application is the commercially available GEN-PROBE APTIMA Specimen Transfer Kit. The components of the APTIMA Specimen Transfer Kit include: (1) a transport tube containing transport media with a penetrable cap and (2) specific instructions for use regarding decontamination and specimen processing procedures. The APTIMA Specimen Transfer Kit may only be used in conjunction with GEN-PROBE APTIMA Assays for the detection of Chlamydia trachomatis and/or Neisseria gonorrhoeae.

The GEN-PROBE® APTIMA® Assay for Chlamydia trachomatis, specifically for its expanded indication with ThinPrep Specimens, underwent a clinical study to evaluate its performance.

1. Table of Acceptance Criteria and Reported Device Performance:

The document describes the performance in terms of sensitivity and specificity. While explicit acceptance criteria are not called out as "acceptance criteria," the clinical study results are presented, suggesting that these performance metrics were deemed acceptable for the device's expanded use.

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

• Sample Size: 1,647 female subjects were evaluated in the clinical study.
  • 1,288 asymptomatic subjects
  • 359 symptomatic subjects
• Data Provenance: The study was a prospective multi-center clinical study. The data was collected from OB/GYN, family planning, public health, women’s, and STD clinics. The country of origin is not explicitly stated, but the submission to the FDA and use of brand names like Cytyc ThinPrep 2000 System suggest a US-centric study or at least a study adhering to US regulatory standards.

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

• The document does not mention the use of experts to establish the ground truth in the traditional sense of human readers adjudicating images or cases.
• Instead, the ground truth (patient infected status) was established using a patient infected status algorithm. This algorithm relied on the results of two reference Nucleic Acid Amplification Tests (NAATs) on endocervical swab specimens.

4. Adjudication Method for the Test Set:

• Adjudication Method: The patient infected status was determined by an algorithm that used two reference NAATs (APTIMA Combo 2 Assay and APTIMA CT Assay) on endocervical swab specimens.
  • An infected patient status required both reference NAATs to be positive.
  • A non-infected patient status required at least one reference NAAT to be negative.
  • This can be considered a form of "2-out-of-2" positive for infection, and "1-out-of-2" negative for non-infection, rather than human adjudication.

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

• No MRMC comparative effectiveness study was done. This study focuses on the standalone performance of the APTIMA Assay for Chlamydia trachomatis when using PreservCyt liquid Pap specimens, not a comparison involving human readers with and without AI assistance.

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

• Yes, a standalone performance evaluation was done. The clinical study directly assessed the performance of the APTIMA CT Assay on PreservCyt liquid Pap specimens against the defined patient infected status algorithm. This represents the algorithm's performance without direct human interpretation of the assay results, other than performing the lab test.

7. The Type of Ground Truth Used:

• Algorithm Consensus (from reference NAATs): The ground truth for the clinical study was established by a patient infected status algorithm based on the results of two highly sensitive and specific reference Nucleic Acid Amplification Tests (NAATs) – the APTIMA Combo 2 Assay and the APTIMA CT Assay – performed on endocervical swab specimens. This is a common and robust method for establishing ground truth for infectious disease diagnostics.

8. The Sample Size for the Training Set:

• The document does not explicitly state the sample size for a training set. Diagnostic assays like the APTIMA Assay are developed through extensive research and analytical validation (limit of detection, analytical specificity, interference, recovery studies) before large-scale clinical validation. The details provided primarily cover the validation study for the expanded indication. It is typical for the assay to have been developed and optimized using various samples, but a specific "training set" in the machine learning sense is not described.

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

• As a specific "training set" and its ground truth establishment are not detailed in the provided document, this information cannot be extracted. The document focuses on the validation of an existing assay for an expanded specimen type. The ground truth for the extensive analytical studies would likely have been established using well-characterized culture isolates and spiked samples with known concentrations of C. trachomatis as described in the Limit of Detection, Analytical Specificity, and Recovery sections (e.g., using IFU/assay as a measure for CT organisms).

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The APTIMA Assay for Chlamydia trachomatis is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection of ribosomal RNA (rRNA) from Chlamydia trachomatis (CT) in clinician-collected endocervical, vaginal and male urethral swab specimens, patient-collected vaginal swab specimens*, and female and male urine specimens. The assay may be used to test specimens from symptomatic and asymptomatic individuals to aid in the diagnosis of chlamydial urogenital disease.

*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 Assay for Chlamydia trachomatis is a target amplification nucleic acid probe test that utilizes target capture for the in vitro qualitative detection of rRNA from Chlamydia trachomatis in clinician-collected endocervical, vaginal and male urethral swab specimens, patient-collected vaginal swab specimens, and female and male urine specimens. The APTIMA Assay for Chlamydia trachomatis (APTIMA CT Assay) may be used to test specimens from symptomatic and asymptomatic individuals to aid in the diagnosis of chlamydial urogenital disease.

Acceptance Criteria and Device Performance for GEN-PROBE® APTIMA® Assay for Chlamydia trachomatis

Due to the nature of the provided document, which is a 510(k) summary for a diagnostic test, much of the detailed information regarding study design, sample sizes, and ground truth establishment (especially for training sets) is not explicitly present in the provided text. The document focuses on demonstrating substantial equivalence to predicate devices and detailing the intended use and performance characteristics.

1. Table of Acceptance Criteria and Reported Device Performance

The provided document does not explicitly state pre-defined acceptance criteria in a quantitative manner as typically seen for AI/ML validation. Instead, it compares the performance of the APTIMA CT Assay with cell culture, highlighting the superior sensitivity of NAATs. The focus is on demonstrating similar or improved performance compared to predicate devices or the "gold standard" of the time (cell culture).

The key performance characteristics highlighted are:

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

The provided document does not explicitly state the specific sample sizes used for the test set. It references several external studies (e.g., Buimer et al., Crothfelt et al., Jaschek et al., Stary et al., Chong et al., Gaydos et al.) to support claims about NAAT performance and the benefits of the APTIMA CT Assay's technology. However, the exact sample sizes and the specific data used for the regulatory submission are not detailed within this text.

Data Provenance: The document does not specify the country of origin of the data referenced in the studies. The studies are described as comparing NAATs to cell culture or discussing technological advancements. The document indicates that "an estimated 783,242 new cases of C. trachomatis infections were reported in 2001 in the United States alone," suggesting a focus on the U.S. context, but this does not directly specify the origin of the clinical study data.

Retrospective or Prospective: The document does not explicitly state whether the studies referenced were retrospective or prospective.

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

The document does not provide details on the number or qualifications of experts used to establish ground truth for the test set. For C. trachomatis diagnostics, particularly in the context of comparisons to cell culture, the "ground truth" would typically be established by highly qualified clinical laboratory personnel adhering to established protocols for the reference method (e.g., cell culture).

4. Adjudication Method for the Test Set

The document does not explicitly state an adjudication method for the test set. Given that the "ground truth" for comparing diagnostic tests like this often relies on a reference method (like cell culture) rather than subjective expert interpretation, a complex adjudication process like 2+1 or 3+1 might not be applicable in the same way as it would for image-based diagnostic AI. Discrepancy resolution for discordant results between the new assay and the reference method would be the more relevant process, but this is not detailed.

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. MRMC studies are typically performed for devices that involve human readers interpreting output (e.g., medical images). The APTIMA CT Assay is an in vitro diagnostic test that provides a qualitative (positive/negative) result without human interpretation of complex patterns, thus an MRMC study is not relevant.

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

The APTIMA CT Assay is a standalone algorithm/device. It is an automated in vitro diagnostic test that provides a direct result from a clinical specimen without real-time human intervention in the interpretation of the core assay output. The performance described (e.g., sensitivity, specificity relative to cell culture) intrinsically represents its standalone performance.

7. The Type of Ground Truth Used

The primary type of ground truth used as a comparator for the performance assessment of NAATs (and by extension for the APTIMA CT Assay's claims) was cell culture. The document states: "Cell culture was once considered to be the 'gold standard' for detection of C. trachomatis." However, it then goes on to state that NAATs have demonstrated higher clinical sensitivity than culture, implying a shift in the perceived "gold standard" or at least a recognition of NAATs' superior performance.

8. The Sample Size for the Training Set

The document does not provide information regarding the sample size for a training set. This is typical for a traditional IVD. Unlike AI/ML devices that explicitly use "training data" to develop algorithms, traditional diagnostic assays are developed and optimized through laboratory research and verification studies, rather than machine learning on a predefined "training set."

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

Similarly to point 8, the concept of a "training set" with a defined "ground truth" in the AI/ML sense is not applicable to this traditional in vitro diagnostic device. The ground truth for developing and verifying such an assay would involve known positive and negative samples, characterized through established laboratory methods, including potentially thoroughly characterized clinical specimens or spiked samples with known concentrations of the pathogen. These would be used for assay optimization, specificity testing, and analytical sensitivity studies during development.

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