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ACE® Theophylline Reagent is intended for the quantitative determination of theophylline in serum using the ACE® clinical chemistry analyzer.

Theophylline is a methylxanthine derivative which is widely used in the treatment of asthma, obstructive lung disease and neonatal apnea. The primary therapeutic effect of theophylline is due to relaxation of bronchial smooth muscle; however, theophylline has a variety of other effects. These include stimulation of the central nervous system and medullary respiratory centers, decreased peripheral vascular resistance, cardiac stimulation, and diuresis. In combination with other clinical data, monitoring serum theophylline levels may provide the physician with useful information to aid in adjusting patient dosage to achieve optimal therapeutic effect while avoiding drug toxicity.

The ACE® Theophylline Reagent contains two reagents, an Antibody/Substrate reagent and an Enzyme Conjugate reagent. The assay uses specific antibodies to theophylline and is based on the competition of an enzyme glucose-6-phosphate dehydrogenase (G6PDH) labeled drug and the free drug from the sample, for a fixed amount of specific antibody binding sites. In the absence of free drug from the sample, the drug-labeled G6PDH is bound by the specific antibody and the enzyme activity is inhibited. This phenomenon creates a relationship between drug concentration in the sample and the enzyme activity. The enzyme G6PDH activity is determined bichromatically on the ACE® at 340/505 nm by measuring its ability to convert NAD+ to NADH.

Here's an analysis of the provided text, focusing on acceptance criteria and the supporting study, formatted as requested:

Acceptance Criteria and Device Performance Study for ACE® Theophylline Reagent

1. Table of Acceptance Criteria and Reported Device Performance

This 510(k) summary directly compares the proposed device's performance to a predicate device. The acceptance criteria are implicitly defined by the predicate device's performance characteristics, demonstrating substantial equivalence.

Note: The predicate device has a slightly tighter between-run precision (%CV) than the proposed device (9.5% vs 14.0%). However, the proposed device shows better within-run precision and a wider assay range. The correlation statistics (slope, intercept, r-value) are also comparable or improved for the proposed device, especially considering the different comparison methods (Commercial theophylline assay for predicate vs. Hitachi 717 for proposed). The FDA's substantial equivalence determination indicates these differences were deemed acceptable.

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

The primary test sets are used for correlation studies.

• Correlation for Predicate Device: N = 88
• Correlation for Proposed Device: N = 50

Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective. It only presents "Non-clinical test results submitted in the premarket notification include within-run and between-run precision and method correlation." Typically, such studies for regulatory submissions are prospective and conducted in a controlled environment, likely in the US where Schiapparelli Biosystems, Inc. is located. However, this is not explicitly stated.

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

For this type of in vitro diagnostic device, "ground truth" for the test set is established by accepted reference methods or commercial assays. The document refers to "Commercial theophylline assay" for the predicate device and "Hitachi 717" for the proposed device. These are established laboratory methods or instruments used for quantitative determination.

There is no mention of "experts" in the sense of clinicians or radiologists establishing ground truth. The ground truth is determined by the output of these reference laboratory instruments or assays.

4. Adjudication Method for the Test Set

Not applicable. This is not an imaging or diagnostic interpretation study requiring expert adjudication. The performance is assessed against quantitative measurements from established laboratory methods.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No, an MRMC comparative effectiveness study was not done. This type of study is typically relevant for interpretative diagnostic devices (e.g., imaging AI) where multiple human readers assess cases with and without AI assistance. This device is an in vitro diagnostic reagent for quantitative measurement.

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

Yes, the performance assessment described (precision, correlation) represents the standalone performance of the ACE® Theophylline Reagent. It evaluates the reagent's ability to accurately and precisely determine theophylline levels without direct human interpretation influencing the measurement outcome. The role of the human is to operate the ACE® clinical chemistry analyzer and follow the assay protocol.

7. The Type of Ground Truth Used

The ground truth used for the correlation studies was quantitative results obtained from:

• A "Commercial theophylline assay" for the predicate device's correlation.
• A "Hitachi 717" analyzer for the proposed device's correlation.

These represent established, presumably validated, laboratory methods for theophylline measurement.

8. The Sample Size for the Training Set

The document does not provide information on a "training set" in the context of machine learning. This device is a chemical reagent for an enzyme immunoassay, not an AI/ML algorithm that requires a separate training set. The development of such a reagent involves chemical formulation, optimization, and validation, rather than algorithmic training.

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

Not applicable. As noted above, this is not an AI/ML device, and thus there is no "training set" in that context. The "ground truth" for the development and optimization of the reagent would involve calibrating it against known concentrations of theophylline and ensuring its chemical and enzymatic reactions perform as expected, which is part of standard analytical chemistry and assay development.

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