(169 days)
The Inverness Medical TestPack + Plus Strep A with OBC Test is intended for the qualitative detection of Group A Streptococcal (Group A Strep) antigen in throat swab specimens from patients with suspected Group A Strep associated pharyngitis and for confirmation of presumptive Group A Strep colonies isolated on culture plates. The test is intended for Professional and Laboratory Use only.
Inverness Medical TestPack + Plus Strep A with OBC Strep A is an immunoassay employing sheep and rabbit polyclonal antibodies and gold colloid particles. The test device uses lateral flow technology; following antigen extraction, the test time is approximately 5 minutes. The Streptococcal Group A specific antigen is extracted from the throat swab using Reagent 1 (2.0 M Sodium Nitrite (& Xylenol Orange) and Reagent 2 (1.0 M Acetic Acid). Following this, Reagent 3 (1.0 M Tris Buffer) is added to neutralise the acid formed by Reagents 1 and 2. The mixture is then dropped into the sample well of the reaction disc from which it migrates through the membrane until it reaches the End of Assay (EOA) Window. As the specimen extract migrates through the membrane, it mobilises the antibody-coated colloid (colloid coated with Rabbit Anti-Strep A antibody). If Group A Streptococcal antigen is present in the specimen it will form a complex with the antibody-colloid. The antibody colloid complex migrates through the membrane and is then captured by the Group A Strep antibody (Sheep polyclonal antibody) in the result window, providing a visual indication of the presence of antigen. The test can be read when the 'End of Assay' (EOA) window has turned pink / red. A pink / red Plus Sign (+) appearing in the result window indicates the presence of the Group A Strep antigen. A Minus Sign (-) indicates no antigen was detected. The device also includes integral Control features.
Acceptance Criteria and Study Details for Inverness Medical TestPack + Plus Strep A with OBC
1. Table of Acceptance Criteria and Reported Device Performance
The provided document does not explicitly state pre-defined acceptance criteria with specific numerical thresholds for sensitivity and specificity. Instead, the study aimed to demonstrate "substantial equivalence" to established culture techniques and other commercially available products. The clinical performance data is presented below, representing the "reported device performance."
| Performance Metric | Reported Device Performance (vs. Culture Methods) |
|---|---|
| Sensitivity | 90.7% (157/173) |
| Specificity | 95.9% (839/875) |
| Overall Agreement | 95.0% (996/1048) |
2. Sample Size and Data Provenance
The study was a "multi-centre study" conducted to evaluate clinical performance.
- Sample Size for Test Set: 1048 throat swab specimens.
- Data Provenance: The document does not explicitly state the country of origin. Given the submitter is from the United Kingdom, it's possible the study involved centers in the UK, but this is not confirmed. The study was "multi-centre," suggesting data from multiple locations.
- Retrospective or Prospective: Not explicitly stated, but the nature of a clinical performance study evaluating a diagnostic device typically implies prospective data collection from patients with suspected Group A Strep pharyngitis.
3. Number of Experts and their Qualifications for Ground Truth
- The ground truth was established by "established culture techniques." While it's implied that laboratory personnel with appropriate qualifications performed the culture methods and interpretations, the document does not specify the "number of experts" involved in establishing this ground truth, nor their specific "qualifications" beyond operating these established techniques.
4. Adjudication Method
Not applicable. The ground truth was based on culture results, which are objective laboratory findings, not subjective interpretations requiring adjudication.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
- No, an MRMC comparative effectiveness study was not explicitly done to assess how much human readers improve with AI vs. without AI assistance.
- The document implies a physicians' office study was conducted to show that physician office personnel could correctly perform and interpret the results of the device (not an AI assistant). This is a study of user performance with the device, not an MRMC study comparing AI-assisted vs. unassisted human readings.
6. Standalone Performance Study
- Yes, a standalone study was done. The reported performance metrics (sensitivity, specificity, overall agreement) are for the device (algorithm only, in this context, the immunoassay device's output) without human interpretation added into the performance calculation, beyond reading the clear positive or negative result on the device.
7. Type of Ground Truth Used
- The primary ground truth used for the clinical performance evaluation was "established culture techniques" for Group A Strep.
8. Sample Size for the Training Set
- The document does not mention a training set or any details about it. This device is a lateral flow immunoassay that relies on chemical reactions and visual indicators, not a machine learning or AI algorithm that typically requires a large training dataset.
9. How the Ground Truth for the Training Set was Established
- Not applicable, as no training set for a machine learning model is mentioned or implied.
§ 866.3740
Streptococcus spp. serological reagents.(a)
Identification. Streptococcus spp. serological reagents are devices that consist of antigens and antisera (excluding streptococcal exoenzyme reagents made from enzymes secreted by streptococci) used in serological tests to identifyStreptococcus spp. from cultured isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by bacteria belonging to the genusStreptococcus and provides epidemiological information on these diseases. Pathogenic streptococci are associated with infections, such as sore throat, impetigo (an infection characterized by small pustules on the skin), urinary tract infections, rheumatic fever, and kidney disease.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 866.9.