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K Number
K061247
Device Name
DIASORIN LIAISON TREPONEMA ASSAY
Manufacturer
DIASORIN, INC.
Date Cleared
2006-07-31

(89 days)

Product Code
LIP
Regulation Number
866.3830
Type
Traditional
Panel
MI
Reference & Predicate Devices
K014233
AI/MLSaMDIVD (In Vitro Diagnostic)TherapeuticDiagnosticis PCCP AuthorizedThirdpartyExpeditedreview
Intended Use

The LIAISON® Treponema Assay and the LIAISON® Treponema Serum Controls uses chemiluminescence immunoassay (CLIA) technology for the qualitative detection of total antibodies of any class (IqG/IgM) directed against Treponema pallidum in human serum. The presence of antibodies to Treponema pallidum specific antigen, in conjunction with nontreponemal laboratory tests and clinical findings, may aid in the diagnosis of syphilis infection. The LIAISON® Treponema Assay is not intended for use in the screening of blood or plasma donors.

Device Description

The method for determination of specific total antibodies to Treponema pallidum is a one-step chemiluminescence immunoassay (CLIA). All assay steps and incubations are performed by the LIAISON® Analyzer, with the exception of initial magnetic particle resuspension. Recombinant antigens specific for Treponema pallidum are used for coating the magnetic particles (solid phase) and are used in the tracer when linked to an isoluminol derivative (isoluminol-antigen conjugate). During the incubation step antibodies present in the calibrators, samples or controls bind to the solid phase. The conjugate reacts with the antibodies already bound to the solid phase. After the incubation, the unbound material is removed with a wash cycle. Subsequently, the starter reagents are added and a flash Chemiluminescence reaction is induced. The light signal and hence the amount of isoluminol-antigen conjugate is measured by a photomultiplier as relative light units (RLU) and is indicative of total antibodies to Treponema pallidum present in calibrators, controls or samples.

AI/ML Overview

Here's a breakdown of the acceptance criteria and study information for the DiaSorin LIAISON® Treponema Assay, based on the provided text:

Acceptance Criteria and Device Performance

The acceptance criteria are implied by the "Percent Agreement" values achieved by the device in comparison to a predicate device (Trinity CAPTIA™ Syphilis (T.pallidum) G) and adjudicated results. While explicit pre-defined thresholds for "acceptance" are not stated, the high agreement percentages are presented as evidence that the device meets its intended use.

Acceptance Criteria Category (Implied by Study)Acceptance Criteria (Implied)Reported Device Performance (LIAISON® Treponema Assay)
Study 1: Clinical Laboratory Screen Test
Medically Diagnosed Syphilis InfectionHigh Positive Agreement97.7% (95% CI = 94.9 – 99.2%) after resolution
High Negative AgreementN/A (Focus on Positive)
High Overall Agreement97.7% (95% CI = 94.9 – 99.2%) after resolution
Samples sent for Syphilis testingHigh Positive AgreementN/A (Focus on Overall)
High Negative AgreementN/A (Focus on Overall)
High Overall Agreement98.7% (95% CI = 97.8 - 99.3%) after resolution
HIV Positive SamplesHigh Positive AgreementN/A (Focus on Overall)
High Negative AgreementN/A (Focus on Overall)
High Overall Agreement94.5% (95% CI = 90.4 – 97.2%) after resolution
Pregnancy SamplesHigh Positive Agreement100% (95% CI = 98.2 – 100%) after resolution
High Negative Agreement100% (95% CI = 98.2 – 100%) after resolution
High Overall Agreement100% (95% CI = 98.2 – 100%) after resolution
Apparently Healthy AdultsHigh Positive AgreementN/A (Focus on Overall)
High Negative AgreementN/A (Focus on Overall)
High Overall Agreement98.3% (95% CI = 97.3 - 99.0%) after resolution
Study 2: Diagnostic Confirmatory Test
RPR/VDRL Positive SamplesHigh Positive Agreement100% (95% CI = 98.2 - 100%) after resolution
High Negative AgreementN/A (Focus on Positive)
High Overall Agreement100% (95% CI = 98.2 - 100%) after resolution

Study Details

  1. Sample Sizes Used for the Test Set and Data Provenance:

    • Study 1 (Clinical Laboratory Screen Test):
      • Medically Diagnosed Syphilis Infection: n=178 (51 from US, 127 from Europe). Retrospective.
      • Laboratory samples sent for Syphilis testing: n=999. Prospective.
      • HIV Positive Samples: n=200. Prospective.
      • Pregnancy Samples: n=200. Prospective.
      • Apparently Healthy Adults: n=992. Prospective.
    • Study 2 (Diagnostic Confirmatory Test):
      • RPR/VDRL Positive Samples: n=204. Retrospective.

    Overall, data provenance includes both retrospective and prospective samples from the US and Europe.

  2. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of those Experts:
    The document does not explicitly state the number or qualifications of experts establishing the initial ground truth for the test set. However, it mentions "Medically Diagnosed Syphilis infection" samples, implying clinical diagnosis by medical professionals. The comparator device (Trinity CAPTIA™ Syphilis (T.pallidum) G) was used as the primary comparative method.

  3. Adjudication Method for the Test Set:
    Discordant samples between the LIAISON® Treponema Assay and the comparator Trinity CAPTIA™ kit were further tested. The adjudication method involved:

    • Repeating equivocal results in duplicate on both the Trinity CAPTIA™ kit and the LIAISON® Treponema assay.
    • Repeating all positive samples on the Trinity CAPTIA™ kit in duplicate.
    • Testing discordant samples with a non-treponemal test (RPR) and another treponemal kit (TP-PA) capable of detecting total antibodies.
    • The resolution of discordants was carried out following the Algorithm suggested by Victoria Pope Ph.D.
      This implies a type of reflex testing and expert-informed consensus/algorithm-based resolution using multiple established methods (RPR, TP-PA) to determine the final ground truth for discordant samples.

  4. 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:
    No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This study is for an immunoassay device and does not involve human readers interpreting images or data to be assisted by AI. The comparison is between two automated laboratory tests.

  5. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was Done:
    Yes, this was a standalone performance study. The LIAISON® Treponema Assay itself is an automated chemiluminescence immunoassay (CLIA) device. The performance data presented are for the device's output (qualitative detection of antibodies) compared to another lab test, without human interpretation as part of the primary outcome measure.

  6. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc):
    For the initial unadjudicated results, the ground truth was largely based on the results of the predicate device (Trinity CAPTIA™ Syphilis (T.pallidum) G), along with clinical diagnosis for "Medically Diagnosed Syphilis Infection" samples. For discordant samples, the ground truth was established through a combination of confirmatory laboratory tests (RPR, TP-PA) and an established clinical algorithm (Victoria Pope Ph.D.'s algorithm). This suggests a form of expert-informed consensus based on a diagnostic algorithm and multiple laboratory tests.

  7. The Sample Size for the Training Set:
    The document does not mention a separate "training set" for the DiaSorin LIAISON® Treponema Assay. Immunoassays typically do not have a training set in the same way machine learning algorithms do. The "development" of the assay would involve internal optimization using various known samples, but these are not explicitly detailed as a distinct "training set" in the context of this regulatory submission which focuses on the clinical validation/test set.

  8. How the Ground Truth for the Training Set was Established:
    As no explicit training set is detailed, information on how its ground truth was established is not provided.

§ 866.3830

Treponema pallidum treponemal test reagents.(a)
Identification. Treponema pallidum treponemal test reagents are devices that consist of the antigens, antisera and all control reagents (standardized reagents with which test results are compared) which are derived from treponemal sources and that are used in the fluorescent treponemal antibody absorption test (FTA-ABS), theTreponema pallidum immobilization test (T.P.I.), and other treponemal tests used to identify antibodies toTreponema pallidum directly from infecting treponemal organisms in serum. The identification aids in the diagnosis of syphilis caused by bacteria belonging to the genusTreponema and provides epidemiological information on syphilis.(b)
Classification. Class II (performance standards).