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For in vitro diagnostic use with the IMMULITE and IMMULITE 1000 Analyzers - for the quantitative measurement of intact parathyroid hormone (parathyrin, PTH) in EDTA plasma or serum. It is intended as an aid in the differential diagnosis of hypercalcemia and hypocalcemia and can be used intraoperatively.

IMMULITE/IMMULITE 1000 Turbo Intact PTH is a solid-phase, chemiluminescent immunometric assay employing a goat polyclonal anti-PTH (44-84) antibody as the capture antibody and a goat polyclonal anti-PTH (1-34) antibody conjugated to alkaline phosphatase as the detection antibody.

Here's an analysis of the IMMULITE®/IMMULITE® 1000 Turbo Intact PTH device's acceptance criteria and the supporting studies:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Mayo Clinic Study: 47 parathyroid gland surgery patients.
• Washington University/Barnes Jewish Hospital Study:
  • Study Group (with intraoperative PTH): 49 patients.
  • Control Group (without intraoperative PTH): 55 patients.
• Data Provenance: Retrospective, as the device was previously cleared (K992105) and these studies compared the already available device's performance to clinical data. The studies were conducted in the US (Mayo Clinic, Rochester, Minnesota and Washington University School of Medicine/Barnes Jewish Hospital, St. Louis, Missouri).

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 or specific qualifications of experts establishing the ground truth for the test set in terms of individual review of each case.

However, the "ground truth" for the device's efficacy in the clinical studies was implicitly established through:

• Clinical outcomes: "clinically cured," "achieved normocalcemia postoperatively." This implies assessment by treating physicians/surgeons, likely qualified in endocrinology and/or surgery, whose consensus on patient's post-operative status served as a form of ground truth.
• "Generally accepted guideline": The 50% decrease in PTH from baseline is a widely accepted clinical guideline in parathyroid surgery, implying a collective expert consensus within the medical community.

4. Adjudication Method for the Test Set

The document does not describe a formal adjudication method (like 2+1 or 3+1) for establishing ground truth from multiple experts for each patient's outcome. Instead, it relies on:

• Clinical outcomes: The patients' actual post-operative clinical status (e.g., cure, normocalcemia) determined by their treating medical teams.
• Established clinical guidelines: The 50% PTH decrease rule, which is a pre-defined and widely accepted criterion.

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

This involves an in vitro diagnostic (IVD) assay, not an AI-powered image analysis device or a system requiring human "readers" in the context of interpreting AI output. Therefore, an MRMC study is not applicable, and no effect size for human improvement with "AI assistance" is provided or relevant. The "assistance" here is a rapid laboratory test providing objective numbers to the surgeon.

The Washington University study did compare a group of patients receiving intraoperative PTH determinations (the device's output) to a control group that did not. This isn't an "AI assistance" scenario, but rather a direct comparison of a surgical workflow with and without the device. The "effect size" in this context could be viewed as:

• Identical physiological outcomes: 90% vs 89% normocalcemia (indicating no negative impact and equivalent success).
• Reduced frozen section use: Statistically significantly less (p<0.0001) in the study group, demonstrating a positive impact on surgical efficiency/practice.

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

Yes, the device is a standalone in vitro diagnostic assay. It measures PTH levels and provides a quantitative result. There is no "human-in-the-loop" performance in terms of interpreting algorithmic output for diagnosis in the way one would for an AI imaging device. The device itself performs the measurement, and the quantitative result is then used by the surgeon in conjunction with clinical guidelines.

7. The Type of Ground Truth Used

The ground truth used in these studies was primarily:

• Clinical outcomes/follow-up Data: Post-operative clinical cure, achievement of normocalcemia, and the efficacy of the surgery.
• Expert Consensus/Established Guidelines: The "generally accepted guideline that a 50% or greater decrease from the baseline PTH value suggests complete tumor removal."

8. The Sample Size for the Training Set

The document states that the IMMULITE/IMMULITE 1000 Turbo Intact PTH assay kit has not changed from its original FDA clearance on July 6, 1999 (K992105). This 510(k) is for demonstrating performance equivalence for a specific intraoperative use of an already cleared device.

Therefore, there isn't a "training set" in the context of developing a new algorithm or model for this 510(k) submission. The initial development and validation of the assay (which would involve a "training set" to establish its analytical characteristics like precision, linearity, etc.) would have occurred prior to its original 1999 clearance. The studies presented here are validation studies for a specific use case of an already established and cleared device.

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

Since this 510(k) pertains to a specific use of an already cleared device, the concept of a "training set" for this submission is not directly applicable.

For the original development of the IMMULITE/IMMULITE 1000 Turbo Intact PTH assay (prior to K992105), the ground truth for establishing its analytical performance (e.g., accuracy, precision, linearity) would have been established through:

• Reference Methods: Comparison to established standard methods or reference assays for measuring PTH.
• Known Concentrations: Testing samples with known, spiked concentrations of PTH.
• Clinical Correlation: Initial studies correlating assay results with clinical diagnoses and outcomes to validate its diagnostic utility.

However, these details are not provided in the given document, as it focuses on demonstrating equivalence for a new indication of use for an existing device.

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