(200 days)
The BD ProbeTec™ Trichomonas vaginalis (TV) Q* Amplified DNA Assay, when tested with the BD Viper™ System in Extracted Mode, uses Strand Displacement Amplification technology for the direct, qualitative detection of Trichomonas vaginalis DNA in clinician-collected female endocervical swab specimens, patient-collected vaginal swab specimens (in a clinical setting), and female urine specimens. The assay is indicated for use with asymptomatic and symptomatic females to aid in the diagnosis of trichomoniasis.
The BD ProbeTec Trichomonas vaginalis (TV) Q* Amplified DNA Assay (TVQ Assay) is based on the simultaneous amplification and detection of target DNA using amplification primers and fluorescently-labeled detector probes. The reagents for 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. The BD Viper™ System pipettes a portion of the purified DNA solution from each Extraction Tube into a Priming Microwell to rehydrate the contents. After a brief incubation, the reaction mixture is transferred to a corresponding, prewarmed Amplification Microwell which is sealed to prevent contamination and then incubated in one of the two thermally-controlled fluorescent readers. The presence or absence of Trichomonas vaginalis DNA is determined by calculating the peak fluorescence (Maximum Relative Fluorescent Units (MaxRFU) over the course of the amplification process and by comparing this measurement to a predetermined threshold value.
In addition to the fluorescent probe used to detect amplified TV target DNA, a second labeled oligonucleotide is incorporated in each reaction Control (EC) oligonucleotide is labeled with a different dye than that used for detection of the TV specific target and is used to confirm the validity of the extraction process. The EC is dried in the Extraction Tubes and is rehydrated upon addition of the specimen and extraction reagents. At the end of the extraction process, the EC fluorescence is monitored by the BD Viper System and an automated algorithm is applied to both the EC and target-specific signals to report results as positive, negative, or EC failure.
BD ProbeTec™ Trichomonas Vaginalis (TV) Q* Amplified DNA Assay - Acceptance Criteria and Study Details
1. Table of Acceptance Criteria and Reported Device Performance
The provided document does not explicitly state pre-defined acceptance criteria for clinical performance (sensitivity and specificity). However, it reports the clinical performance observed in the study. Based on the "Conclusion" section stating that the "analytical and clinical study results... support the determination of substantial equivalence in accordance with the intended use," it can be inferred that the reported performance met the implicit or explicit requirements for regulatory approval.
| Metric | Specimen Type (Status) | Reported Performance (95% CI) | Implied Acceptance Criteria (Based on Approval) |
|---|---|---|---|
| Sensitivity | Neat Urine (Asymptomatic) | 93.1% (78.0%, 98.1%) | High sensitivity, likely >90% |
| Neat Urine (Symptomatic) | 96.4% (89.9%, 98.8%) | High sensitivity, likely >90% | |
| Neat Urine (Total) | 95.5% (90.0%, 98.1%) | High sensitivity, likely >90% | |
| Vaginal (Asymptomatic) | 93.5% (79.3%, 98.2%) | High sensitivity, likely >90% | |
| Vaginal (Symptomatic) | 100.0% (95.7%, 100.0%) | Very high sensitivity, likely >95% | |
| Vaginal (Total) | 98.3% (93.9%, 99.5%) | Very high sensitivity, likely >95% | |
| Endocervical (Asymptomatic) | 92.2% (81.5%, 96.9%) | High sensitivity, likely >90% | |
| Endocervical (Symptomatic) | 98.8% (93.5%, 99.8%) | Very high sensitivity, likely >95% | |
| Endocervical (Total) | 96.3% (91.6%, 98.4%) | Very high sensitivity, likely >95% | |
| All Specimen Types (Asymptomatic) | 92.8% (86.4%, 96.3%) | High sensitivity, likely >90% | |
| All Specimen Types (Symptomatic) | 98.4% (96.0%, 99.4%) | Very high sensitivity, likely >95% | |
| Overall | 96.7% (94.3%, 98.1%) | Very high sensitivity, likely >95% | |
| Specificity | Neat Urine (Asymptomatic) | 99.6% (97.9%, 99.9%) | Very high specificity, likely >98% |
| Neat Urine (Symptomatic) | 98.1% (96.1%, 99.1%) | Very high specificity, likely >98% | |
| Neat Urine (Total) | 98.7% (97.5%, 99.3%) | Very high specificity, likely >98% | |
| Vaginal (Asymptomatic) | 99.0% (97.2%, 99.7%) | Very high specificity, likely >98% | |
| Vaginal (Symptomatic) | 99.0% (97.5%, 99.6%) | Very high specificity, likely >98% | |
| Vaginal (Total) | 99.0% (98.0%, 99.5%) | Very high specificity, likely >98% | |
| Endocervical (Asymptomatic) | 99.1% (97.8%, 99.7%) | Very high specificity, likely >98% | |
| Endocervical (Symptomatic) | 99.8% (98.6%, 100.0%) | Very high specificity, likely >98% | |
| Endocervical (Total) | 99.4% (98.6%, 99.8%) | Very high specificity, likely >98% | |
| All Specimen Types (Asymptomatic) | 99.2% (98.5%, 99.6%) | Very high specificity, likely >98% | |
| All Specimen Types (Symptomatic) | 99.0% (98.2%, 99.4%) | Very high specificity, likely >98% | |
| Overall | 99.1% (98.6%, 99.4%) | Very high specificity, likely >98% |
2. Sample Size for the Test Set and Data Provenance
- Test Set Sample Size:
- Urine specimens: 735 compliant subjects
- Vaginal specimens: 832 compliant subjects
- Endocervical specimens: 995 compliant subjects
- All specimen types combined: 2568 compliant subjects (This refers to total tests, not unique subjects)
- Data Provenance: Prospective collection from subjects attending family planning, OB/GYN, and sexually transmitted disease clinics at seven geographically diverse clinical sites in North America.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Qualifications
The document specifies the use of a "composite reference method" for establishing ground truth, consisting of Wet Mount and InPouch TV Culture. These are laboratory-based methods, not expert human readers for image interpretation. Therefore, the concept of "number of experts" and "qualifications of those experts" as it might apply to an AI image recognition device is not directly applicable here. The ground truth relies on the performance of these established microbiological diagnostic techniques.
4. Adjudication Method for the Test Set
The document describes a "composite reference method" for establishing ground truth. The first two clinician-collected vaginal swabs were randomized: one for Wet Mount and the other for InPouch TV Culture. While the specific adjudication rules are not detailed (e.g., if one test was positive and the other negative, how a "composite" result was derived), the setup implies that the results from these two reference methods were combined to form the final ground truth. It is not explicitly stated if a third, independent expert or method was used for discordant results between Wet Mount and InPouch TV Culture.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not conducted as this is a diagnostic assay for the direct detection of DNA, not an AI-assisted interpretation of images or other data by human readers. The study focuses on the standalone performance of the assay compared to established laboratory reference methods.
6. Standalone Performance (Algorithm Only without Human-in-the-Loop Performance)
Yes, a standalone performance study was conducted. The main clinical performance evaluation (sensitivity and specificity) presented in Table 4 ("TVQ ASSAY VS COMPOSITE REFERENCE RESULT CULTURE OF INPOUCH TV TABLE 4: CULTURE AND WET MOUNT (BY SPECIMEN TYPE AND SYMPTOMATIC STATUS)") represents the performance of the BD ProbeTec TVQ Assay (algorithm only) against the composite reference method. There is no human-in-the-loop component mentioned for the interpretation of the assay's results. The BD Viper System provides an automated result (positive, negative, or EC failure).
7. Type of Ground Truth Used
The ground truth used was a composite reference method consisting of:
- Wet Mount
- InPouch TV Culture
These are considered established microbiological diagnostic methods for Trichomonas vaginalis.
8. Sample Size for the Training Set
The document does not provide information regarding a specific training set size. This indicates that the device's development likely used a different methodology, such as being designed and optimized based on known biological principles and analytical performance rather than a large machine learning training dataset. For an in vitro diagnostic (IVD) assay like this, analytical studies (LOD, specificity, interference) and subsequent clinical validation are typical, rather than a "training set" in the machine learning sense.
9. How the Ground Truth for the Training Set Was Established
As no specific training set is mentioned in the context of machine learning, there is no information provided on how ground truth for such a set was established. The development of the assay would have involved standard molecular biology techniques and validation against known positive and negative controls (analytical truth) rather than a clinical training set with "ground truth" derived from patient outcomes or expert consensus on clinical samples.
§ 866.3860
Trichomonas vaginalis nucleic acid assay.(a)
Identification. ATrichomonas vaginalis nucleic acid assay is a device that consists of primers, probes, enzymes, and controls for the amplification and detection of trichomonas nucleic acids in endocervical swabs, vaginal swabs, and female urine specimens, from women symptomatic for vaginitis, cervicitis, or urethritis and/or to aid in the diagnosis of trichomoniasis in asymptomatic women. The detection of trichomonas nucleic acids, in conjunction with other laboratory tests, aids in the clinical laboratory diagnosis of trichomoniasis caused byTrichomonas vaginalis .(b)
Classification. Class II (special controls). The special controls are set forth in FDA's guideline document entitled: “Class II Special Controls Guideline: Nucleic Acid Amplification Assays for the Detection ofTrichomonas vaginalis; Guideline for Industry and Food and Drug Administration Staff.” See § 866.1(e) for information on obtaining this document.