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The AspirinWorks® Test Kit is an enzyme-linked immunoassay (ELISA) to determine levels of 11-Dehydro Thromboxane B2 (11dhTxB2) in human urine, which aids in the qualitative detection of aspirin effect in apparently healthy individuals post ingestion. For professional use only. The AspirinWorks® Test Kit is intended for use in clinical (hospital and reference) laboratories.

An ELISA for the detection of urinary 11-Dehydro Thromboxane B2 (11dhTxB2). Goat anti-mouse IgG polyclonal antibody (Jackson ImmunoResearch Laboratories, Inc, West Grove, PA) is coated onto 96microwell plates. Reference, control, and patient samples are diluted in a Tris-based sample diluent (pH 9.0) and added to the microwells. An 11dhTxB2 tracer (11dhTxB2 linked to alkaline phosphatase, (AP); Cayman Chemical Company, Ann Arbor, MI) is then added to all wells except assay blanks, followed by the addition of an anti-11dhTxB2 murine monoclonal antibody (Cayman Chemical Company) to all wells except assay blanks. The maximum binding wells (Bo) contain sample diluent, tracer, and monoclonal antibody, but no unlabeled 11dhTxB2. The plate is then covered with the plastic sheet provided in the kit, and incubated at room temperature on a rotary shaker at 300-600 pm for two hours. The AP-Tracer and unlabeled 11dhTxB2 from the reference curve/controls/samples compete for binding to the anti-11dhTxB2 monoclonal antibody, which is bound to the plate by the goat anti-mouse polyclonal antibody. After incubation, the reaction solution is removed from the wells followed by five washes with TBS/Tween 20. The pNPP substrate is then added and the plate is covered and incubated with shaking for 30 minutes. The reaction is stopped by the addition of Stop Solution (0.1M EDTA) to the wells, and the plate is read at 405-420 mm. Results are compared to the reference curve and expressed in pg/ml. Patient results are then normalized using the creatinine concentration of the sample, as measured by a separate assay.

The Corgenix AspirinWorks® Test Kit is an enzyme-linked immunoassay (ELISA) designed to measure levels of 11-Dehydro Thromboxane B2 (11dhTxB2) in human urine. This measurement aids in the qualitative detection of aspirin effect in apparently healthy individuals post ingestion.

1. Acceptance Criteria and Reported Device Performance:

The document implicitly defines acceptance criteria through the reported performance that demonstrates the device's ability to detect aspirin effect consistently with established literature. While explicit numerical acceptance criteria for sensitivity/specificity against a definitive gold standard are not provided, the "cutoff" value and the agreement with published aspirin non-responsiveness rates serve as the basis for acceptance.

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

• Test Set Sample Sizes:
  • Aspirin-naive individuals: 204 samples.
  • Aspirin users (81 mg/day): 163 samples.
  • Aspirin users (325 mg/day): 38 samples.
  • Total aspirin users: 201 samples.
• Data Provenance: The studies are described as "clinical studies" and "non-clinical studies." No specific country of origin is mentioned, but the submission is to the FDA, suggesting compliance with US regulatory standards. The studies appear to be prospective, where samples were collected and tested to evaluate the device's performance in detecting aspirin effect or lack thereof.

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

The document does not explicitly state the number of experts used or their qualifications for establishing ground truth for the clinical studies. The classification of individuals as "not taking aspirin" or "taking various doses of aspirin" likely served as the primary categorisation for ground truth regarding aspirin exposure. The ground truth for "aspirin effect" was established by the AspirinWorks Test Kit measurement itself, with the clinical studies validating that the obtained results (e.g., non-responsiveness rates) are consistent with existing "published literature" on aspirin non-responsiveness.

4. Adjudication method for the test set:

Not applicable. The study involved a comparison of device measurements against defined categories (aspirin user vs. non-user) and consistency with published literature, rather than expert adjudication of individual case results for a diagnostic decision.

5. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

Not applicable. This is an ELISA-based diagnostic kit, not an AI-assisted diagnostic imaging or interpretation device that would involve human readers.

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

Yes, the studies evaluate the standalone performance of the AspirinWorks® Test Kit. The device, an ELISA kit, operates as a standalone diagnostic tool to measure 11dhTxB2 levels. The results are interpreted against a predetermined cutoff (≤1500 pg 11dhTxB2/mg creatinine) to indicate an aspirin effect. There is no mention of a human-in-the-loop component in the interpretation of the 11dhTxB2 measurement itself.

7. The type of ground truth used:

The ground truth for the clinical studies was based on:

• Stated aspirin usage: Patients were categorized as "individuals not taking aspirin" or "individuals taking various doses of aspirin."
• Consistency with outcomes/published literature: The observed rates of "lack of aspirin effect" (i.e., aspirin non-responsiveness) in the aspirin-taking groups were compared to and found to be "consistent with those in published literature for aspirin non-responsiveness or lack of aspirin effect." This implies that the accepted understanding of aspirin's physiological effect and its variability was used as a reference.

8. The sample size for the training set:

The document does not explicitly describe a separate "training set" in the context of machine learning or algorithm development. For an ELISA kit, development typically involves analytical validation (precision, accuracy, range, linearity, interference) and then clinical validation. The "clinical studies" mentioned (with 204 aspirin-naive and 201 aspirin-user samples) likely served as the primary dataset for establishing the clinical performance and cutoff value, which in some contexts could be viewed as a development/validation set.

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

As no explicit "training set" is described for algorithm development in the AI sense, this question is not fully applicable. However, for the development and establishment of the device's performance characteristics and cutoff:

• The "cutoff for aspirin effect at ≤1500 pg 11dhTxB2/mg creatinine" was "established" through the "two different clinical studies." This suggests an empirical derivation from the collected clinical data, likely aiming to optimize the correlation between urinary 11dhTxB2 levels measured by the kit and observed aspirin status, while also ensuring consistency with published literature on aspirin non-responsiveness. The ground truth for these studies was the patient's self-reported or clinically determined aspirin usage status.

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