(147 days)
REMEL's Xpect™ Giardia kit is an in vitro qualitative immunoassay for the detection of Giardia antigens in preserved and unpreserved fecal specimens. This test is intended as an aid in the laboratory diagnosis of suspected Giardia infections.
The Xpect™ Giardia Lateral Flow Assay is a chromatographic immunoassay that detects the presence of Giardia antigen. The test utilizes sample wicking to capture Giardia antigen on a discrete test line containing antigen-specific antibodies for Giardia. A specimen is added to a dilution tube containing a buffered solution. A conjugate containing colored micro-particles linked to murine monoclonal antibody specific for Giardia is added. The mixture is dispensed into the sample well of the device and wicks along a membrane containing capture antibody stripes. The Giardia immune complex, if present, reacts with anti- Giardia antibody at the test line. Antibody-labeled microparticles not bound at the test line are later captured at the control line containing anti-mouse antibody. A blue line of any intensity (light blue to black) will appear at the Giardia test position if Giardia antigen is present. A complete line at the Control position indicates that the test is working properly.
Here's a breakdown of the acceptance criteria and study information for the Xpect™ Giardia Lateral Flow Assay, based on the provided 510(k) notification:
Acceptance Criteria and Reported Device Performance
| Acceptance Criteria | Reported Device Performance (Xpect™ Giardia) |
|---|---|
| Preamble device comparison: Not substantially equivalent to the predicate device | Substantially equivalent to the predicate device (Becton Dickinson ColorPAC™ Giardia/Cryptosporidium Rapid Assay) |
| Sensitivity for Giardia detection: | 97.9% (95/97); 95% Confidence Interval (CI) = 92.8-99.4% |
| Specificity for Giardia detection: | 97.1% (464/478); 95% CI = 95.1-98.2% |
| Percent Agreement with Predicate Device (Positive Agreement): | 92.3% (24/26) |
| Percent Agreement with Predicate Device (Negative Agreement): | 94.2% (114/121) |
| Overall Percent Agreement with Predicate Device: | 93.9% (138/147) |
| Cross-reactivity: No cross-reactivity with specified organisms | No cross-reactivity observed with a list of 24 organisms/pathogens (excluding Astrovirus and Caliciviruses for which it was not established). |
| Interfering Substances: No interference from specified substances | No interference with expected results from blood, mucin, fecal fat, or common anti-diarrheal products (Pepto-Bismol®, Imodium® A-D, and Kaopectate®). |
| Reproducibility: Consistent results across sites and days with varying activity. | 100% of 630 samples tested produced the expected result across seven sites (including one in-house) on three separate days with ten blinded samples of varying activity. |
Study Information
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Sample Size Used for the Test Set and Data Provenance:
- Clinical Performance Study (compared to microscopy):
- Total samples with Giardia present by microscopy: 97
- Total samples with Giardia absent by microscopy: 478
- Total samples in this comparison: 575 (97 positive + 478 negative)
- Data Provenance: The study was evaluated at "six geographically diverse laboratories," indicating a multi-center, likely prospective collection of clinical samples. The country of origin is not explicitly stated but can be inferred to be within the US given the submission to the FDA.
- Comparison to Predicate Device:
- Total samples: 147 (26 positive by predicate, 121 negative by predicate).
- Clinical Performance Study (compared to microscopy):
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Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications:
- The primary ground truth for the clinical performance study was microscopy. The document does not specify the number of experts (e.g., medical technologists, parasitologists) involved, nor their specific qualifications (e.g., years of experience). It simply states the comparison was "compared to microscopy."
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Adjudication Method for the Test Set:
- The document does not explicitly state an adjudication method (like 2+1, 3+1). It implies that the microscopy results served as the definitive ground truth for the comparison.
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Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
- No, an MRMC comparative effectiveness study involving human readers with and without AI assistance was not done. This device is a rapid diagnostic test (lateral flow immunoassay), not an AI-powered diagnostic imaging or interpretation tool designed to assist human readers.
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Standalone (Algorithm Only) Performance:
- Yes, the performance presented in the "Sensitivity/Specificity" table is the standalone performance of the Xpect™ Giardia Lateral Flow Assay, as it directly compares the device's results to the microscopy ground truth. It operates independently of human interpretation beyond reading the positive/negative line.
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Type of Ground Truth Used:
- The primary ground truth used for the clinical performance evaluation was microscopy, which involves expert examination of fecal specimens for the presence of Giardia parasites.
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Sample Size for the Training Set:
- The document does not specify a separate "training set" or its size. As this is a lateral flow immunoassay, the development process would involve analytical studies and optimization rather than machine learning training on a distinct dataset. The studies described are performance validation studies.
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How the Ground Truth for the Training Set Was Established:
- Since a separate training set, in the context of machine learning, is not applicable or described for this device, the method for establishing its ground truth is not provided. The ground truth for the validation test set was established by microscopy.
§ 866.3220
Entamoeba histolytica serological reagents.(a)
Identification. Entamoeba histolytica serological reagents are devices that consist of antigens and antisera used in serological tests to identify antibodies toEntamoeba histolytica in serum. Additionally, some of these reagents consist of antisera conjugated with a fluorescent dye (immunofluorescent reagents) used to identifyEntamoeba histolytica directly from clinical specimens. The identification aids in the diagnosis of amebiasis caused by the microscopic protozoan parasiteEntamoeba histolytica and provides epidemiological information on diseases caused by this parasite. The parasite may invade the skin, liver, intestines, lungs, and diaphragm, causing disease conditions such as indolent ulcers, an amebic hepatitis, amebic dysentery, and pulmonary lesions.(b)
Classification. Class II (special controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 866.9.