(45 days)
This Fecal Occult Blood (FOB) Ravid Test is an immunochemical device intended for the qualitative detection of Fecal Occult Blood by laboratories or physicians offices. It is useful to determining gastrointestinal (GI) bleeding found in a number of gastrointestinal (GI) disorders, e.g., diverticulitis, colitis, polyps, and colorectal cancer.
This test is recommended for use in 1) routine physical examinations. when hospital patients are first admitted, 2) hospital monitoring for bleeding in patients. 3) screening for colorectal cancer or gastrointestinal bleeding from any source.
The Instant-View™ Fecal Occult Blood Rapid Test is an immunochemical device for the qualitative detection of Fecal Occult Blood.
Here's a breakdown of the acceptance criteria and study information for the Instant-View™ Fecal Occult Blood Rapid Test, based on the provided text:
1. Table of Acceptance Criteria and Reported Device Performance
| Performance Characteristic | Acceptance Criteria (Implicit) | Reported Device Performance |
|---|---|---|
| Sensitivity | Detect human Hemoglobin (hHb) at or above 50 µg hHb/g feces (50 ng/ml extraction buffer). | Able to detect hHb at 50 ng/ml (100% agreement with predicate). |
| Prozone Effect | No interference observed up to a certain high hHb concentration. | No interference up to 2000 ng hHb/ml (equivalent to 2 mg hHb/g feces). |
| Specificity (Cross-reactivity) | No false positives with hemoglobin from other species (beef, chicken, fish, horse, goat, pig, rabbit, sheep). | Gave negative results with other species' Hb; positive when hHb was present. |
| Interference (Dietary Substances) | No false positives or interference from common dietary substances (broccoli, cantaloupe, cauliflower, horseradish, parsnip, red radish, turnip, horseradish peroxidases, dietary iron, Vitamin C). | Gave negative results with all extracts; positive when hHb was present. No interference observed with dietary iron/Vitamin C. |
| Interference (Toilet Water Additives) | No false positives from toilet bowl deodorizers/fresheners/cleaners. Sensitivity may vary, requiring removal for optimal performance. | No false positives. Some decreased sensitivity by over three-fold, others no effect. |
| Interference (Toilet Water Contaminants) | No false positives due to residual human blood in toilet if concentration below 50 ng/ml. Instructions for flushing before use and proper sample collection required. | False positives may occur if residual human blood is ≥ 50 ng/ml. |
| Reproducibility (POL) | High agreement with expected results across different users and sites. | 97.7% agreement (average) with expected results at three Physician Office Laboratories (POLs). |
| Reproducibility (Reference Lab) | High agreement with expected results in a controlled lab setting. | 99% agreement with expected results at a Reference Laboratory. |
| Overall Accuracy | High accuracy (composite of sensitivity, specificity, reproducibility). | 98% overall accuracy. |
| Specimen Stability at 35°C (95°F) | Expected stability for a reasonable duration. | Stable for up to 8 days. |
| Specimen Stability at 4°C (39.2°F) | Expected stability for a longer duration. | Stable for up to 6 months. |
| Specimen Stability at -20°C (-4°F) | Expected stability for extended storage. | Stable for at least 2 years. |
2. Sample Sizes and Data Provenance
- Sensitivity Study (Test Set): 40 stool extraction samples, spiked with hHb at five concentration levels (0, 37.5, 50, 62.5, 2000 ng/ml), with 8 samples per level. The study was conducted in-house. Data provenance is implied to be internal (Alfa Scientific Designs, Inc.), likely U.S.-based as the manufacturer is in Poway, CA. It is a prospective, controlled spiking study.
- Reproducibility and Repeatability Studies (Test Set):
- 100 human hemoglobin-free stool extraction specimens, divided into 5 groups (20 each), spiked with hHb at 0, 37.5, 50, 62.5, and 2000 ng/ml. These were collected in-house.
- 120 fresh human hemoglobin-free stool extraction specimens, divided into 5 groups (72 in each), spiked with hHb at 0, 37.5, 50, 62.5, and 2000 ng/ml. These were collected in-house.
- Data provenance is internal (Alfa Scientific Designs, Inc.), likely U.S.-based, and appears to be prospective, controlled spiking studies.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications
The document does not explicitly state the number or qualifications of experts used to establish the ground truth for the test sets. The ground truth for these studies appears to be based on the known spiked concentration of human hemoglobin, rather than expert consensus on clinical samples.
4. Adjudication Method for the Test Set
- For the sensitivity study, "Results were compared with one lot of predicate device, the Hemoccult® Test." This suggests a comparative analysis rather than a formal adjudication of experts.
- For the reproducibility and repeatability studies, "Every test result was read by two independent readers." This indicates a 2-reader independent reading. However, it doesn't specify an adjudication method for disagreements between readers, or how the "expected results" were determined beyond the known spiked concentrations.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was Done
No, a formal MRMC comparative effectiveness study, comparing human readers with AI assistance versus human readers without AI assistance, was not conducted. This device is a rapid diagnostic test, not an AI-powered image analysis system. The comparison was between the Instant-View™ FOB Rapid Test and the predicate device (Hemoccult®) in terms of analytical performance.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was Done
Yes, the studies described are essentially "standalone" in the context of the device itself. The device (a rapid test) provides a qualitative result, and the studies evaluated this result directly against known sample compositions. The "human-in-the-loop" aspect is the reading of the test result by a person, but the device's performance is assessed on its inherent ability to detect hHb.
7. The Type of Ground Truth Used
The primary type of ground truth used in these analytical studies is known spiked concentrations of human hemoglobin. This is a controlled, analytical ground truth, not pathology, clinical outcomes, or expert consensus on patient samples.
8. The Sample Size for the Training Set
The document does not specify a distinct "training set" or its sample size. This is typical for traditional rapid diagnostic tests, where the analytical performance is characterized rather than a model being "trained" on data. The studies described are performance validation/verification studies.
9. How the Ground Truth for the Training Set Was Established
As no separate training set is mentioned in the context of machine learning, this question is not directly applicable. If considering the "training" of the device (i.e., its design and manufacturing to meet specifications), the ground truth would be established through internal R&D and analytical testing to ensure the reagents and test strip perform as intended to detect hHb at the specified cutoff.
§ 864.6550 Occult blood test.
(a)
Identification. An occult blood test is a device used to detect occult blood in urine or feces. (Occult blood is blood present in such small quantities that it can be detected only by chemical tests of suspected material, or by microscopic or spectroscopic examination.)(b)
Classification. Class II (special controls). A control intended for use with an occult blood test is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 864.9.