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The DiaSorin LIAISON® Calprotectin assay is an in vitro diagnostic chemiluminescent immunoassay (CLIA) intended for the quantitative measurement, in human stool, of fecal calprotectin, a neutrophilic protein that is a marker of mucosal inflammation. The LIAISON® Calprotectin assay can be used as an aid in the diagnosis of inflammatory bowel diseases (IBD), specifically Crohn's disease and ulcerative colitis, and as an aid in differentiation of IBD from irritable bowel syndrome (IBS). Test results are to be used in conjunction with information obtained from the patients' clinical evaluation and other diagnostic procedures.

The test has to be performed on the LIAISON® XL Analyzer.

The DiaSorin LIAISON® O.S.E.T. Device (Quantitative Stool Extraction and Test) is intended for use in the preparation of human stool specimens for testing in the LIAISON® Calprotectin assay.

The LIAISON® Calprotectin assay is a sandwich assay that uses 2 monoclonal antibodies for capture and detection of calprotectin. The LIAISON® Calprotectin assay must be run on the LIAISON® XL Analyzer, a fully automated system with continuous loading.

Calprotectin is first extracted from human stool samples with LIAISON® Q.S.E.T. Buffer using either the weigh method or the LIAISON® Q.S.E.T. Device. The assay incubates extracted sample, calibrator, control, or calibration verifiers with assay buffer and paramagnetic particles coated with a monoclonal antibody that specifically recognizes the calprotectin heterocomplex. Following incubation, a wash cycle is performed to remove any unbound material. An isoluminol conjugated monoclonal antibody that recognizes calprotectin is then added to the reaction and incubated. The unbound conjugate is removed with a second wash step. Starter reagents are then added and a flash chemiluminescent reaction is initiated. The light signal is measured by a photomultiplier as relative light units (RLU) and is proportional to the concentration of calprotectin present in the calibrators, controls or samples.

All assay steps and incubations are performed by the LIAISON® XL Analyzer. The analyzer software automatically calculates the concentration of calprotectin in the sample. This concentration is expressed in ug/q.

Here's an analysis of the acceptance criteria and supporting studies for the DiaSorin LIAISON® Calprotectin assay, LIAISON® Q.S.E.T. Device, and associated controls/calibrators, based on the provided FDA 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

The FDA 510(k) summary doesn't explicitly state "acceptance criteria" as a separate section with pass/fail thresholds for each performance metric. Instead, the performance studies themselves demonstrate the device's capabilities. I've extracted key performance metrics and their reported results from the document. The implicit "acceptance criteria" here would be that these performance characteristics are adequate for the intended use and comparable to predicate devices, demonstrating substantial equivalence.

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

• Method Comparison (LIAISON Calprotectin vs. Commercial Calprotectin Assay):
  • Sample Size: 164 stool samples.
  • Data Provenance: Not explicitly stated, but implies clinical samples spanning the assay range. It's retrospective in the sense that these samples were then tested on two devices.
• Comparative Clinical Studies (IBD vs. non-IBD, IBD vs. IBS):
  • Sample Size: 240 prospectively collected human stool specimens.
  • Data Provenance: Prospectively collected from subjects with signs and symptoms suggestive of IBD or IBS. Geographic origin is not specified.
• Expected Values (Reference Ranges):
  • Sample Size:
    • Apparently Healthy: 127 subjects (15 pediatric, 112 adult)
    • IBD: 102 subjects (19 pediatric, 333 adults - Note: The document states 19 pediatric and 333 adults for IBD/IBS subjects, but the IBD specific count is 102 total in the table, suggesting a subset. Clarification needed if this were a definitive study report.).
    • IBS: 67 subjects (subset of the 19 pediatric and 333 adults mentioned for IBD/IBS).
    • Other GI: 71 subjects.
  • Data Provenance: Stool samples from apparently healthy donors and subjects with physician-diagnosed IBS and IBD. Not explicitly stated if these were the same 240 samples from the clinical studies or an additional set.
• LIAISON® Q.S.E.T. Device Accuracy (Method Comparison of Extraction):
  • Sample Size: 128 human stool samples.
  • Data Provenance: Not explicitly stated, but human stool samples spanning the measuring range.

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

• Method Comparison (LIAISON Calprotectin vs. Commercial Calprotectin Assay): Ground truth was established by another commercial calprotectin assay, not human experts.
• Comparative Clinical Studies (IBD vs. non-IBD, IBD vs. IBS):
  • Ground Truth Establishment: "Diagnosis of IBD, IBS, or other GI disorder was determined based on the results of colonoscopy, as well as other clinical findings. IBD diagnosis was confirmed by histological assessment of biopsy."
  • Number of Experts/Qualifications: Not specified. This typically would involve gastroenterologists, pathologists (for histological assessment), and other clinicians. The document does not provide details on the number or their specific qualifications (e.g., years of experience, board certification).
• Expected Values: Ground truth was based on "physician diagnosed" health status (apparently healthy, IBS, IBD). Number of physicians or their qualifications are not specified.

4. Adjudication Method for the Test Set

• Adjudication method for clinical diagnosis (ground truth): The document states that IBD diagnosis was confirmed by histological assessment of biopsy in addition to colonoscopy and other clinical findings. This implies a comprehensive clinical evaluation, but it doesn't specify an explicit adjudication process like a 2+1 or 3+1 reader consensus for borderline cases or disagreements among diagnostic methods/experts. It's a "clinical diagnosis" approach.

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

No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. This device is an in-vitro diagnostic (IVD) assay that directly measures a biomarker, not an imaging analysis tool or a decision support system for human readers. Therefore, the concept of human readers improving with AI assistance is not applicable in this context.

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

Yes, the studies presented (method comparison, clinical sensitivity/specificity, analytical performance) represent the standalone performance of the LIAISON® Calprotectin assay. It is an automated chemiluminescent immunoassay run on the LIAISON® XL Analyzer, directly providing quantitative results without human interpretation as part of the primary diagnostic output.

7. The Type of Ground Truth Used

• Clinical Studies:
  • Expert Consensus/Clinical Diagnosis: For IBD, IBS, and other GI disorders, the ground truth was "clinical diagnosis by colonoscopy, as well as other clinical findings," with "histological assessment of biopsy" confirming IBD. This is a form of expert consensus based on established clinical and pathological methods.
• Method Comparison:
  • Comparator Device: The ground truth was established by a "commercial calprotectin assay."
• Expected Values:
  • Physician Diagnosis: "Physician diagnosed" health status.

8. The Sample Size for the Training Set

The provided document describes a 510(k) premarket notification for an IVD kit, which typically involves analytical validation and clinical performance studies, not a "training set" in the context of machine learning model development. For IVDs, the kit components (reagents, calibrators, controls) are manufactured and their performance characteristics are validated extensively. The studies described are validation studies, not training studies. Therefore, there is no "training set" in the machine learning sense for this device. The development of the assay itself would have involved internal optimization and development work, but specific sample sizes for "training" are not typically reported in 510(k) submissions for such assays.

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

As noted above, there is no "training set" in the machine learning sense. The ground truth for the validation studies (clinical and method comparison) are described in point 7.

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