(137 days)
DRx® Qt. hCG is a rapid, single-use, point-of-care device for the quantitative measurement of human chorionic gonadotropin (total ßhCG) in capillary and venous whole blood samples. The device is for professional use as an aid in the assessment of pregnancy status.
The DRx® Ot. hCG device is a single-use, disposable four-channel reflectance photometer integrated with dry reagent chemistry strips and contained within a sealed plastic case. Each unit consists of:
. an optics subassembly that also supports the reagent strips
- a printed circuit board that includes a microprocessor, analog . electronics, battery clips, batteries, silicon diode photodetectors, and j light emitting diodes (LEDs)
- a plastic molded part ("spider") that supports the liquid crystal display ● (LCD), the sample pad and the auto start leads, and also provides optical shielding
- two reagent strips .
- whole blood separation chemistry pad ●
- a desiccant
- liquid crystal display (LCD)
Both test strips are lateral flow immunoassays for measuring hCG between zero and 10,000 mIU/mL. In both strips, a blue color is measured in discrete test zones. The test zones are the areas where the specific reactions occur and concentrations are measured.
The whole blood separation mechanism occurs when the whole blood ~ sample reaches the sample pad and immobilizes the red blood cells. As a result, the plasma freely migrates by capillary action onto the assay strips to complete the final reactions. The hCG reaction proceeds as follows: anti-hCG antibody, conjugated to blue microparticles, migrate across the strip upon the addition of whole blood sample. The amount of blue microparticles captured on the test zones is proportional to the amount of hCG in the sample.
The LEDs and silicon photodetectors compare the reflectances of the color intensities before and after the sample addition. Based on the calibration parameters stored in memory, the numerical concentrations of hCG is calculated. The final assay results are expressed in mIU/mL hCG.
The Metrika, Inc. DRx® Qt. hCG device is a rapid, single-use, point-of-care device for the quantitative measurement of human chorionic gonadotropin (total ßhCG) in capillary and venous whole blood samples, intended for professional use to assess pregnancy status.
Here's an analysis of its acceptance criteria and the study that proves the device meets those criteria:
1. Table of Acceptance Criteria and Reported Device Performance:
The document doesn't explicitly state "acceptance criteria" through numerical targets for the comparative study. Instead, it presents the results of a comparative study against a predicate device and demonstrates strong correlation, implying that the performance achieved is considered acceptable for substantial equivalence. For analytical performance, criteria are implied by the confirmed ranges and specificities.
| Performance Metric | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Analytical Sensitivity | Sensitive to low hCG levels | Sensitive to 5 mIU/mL hCG. |
| Analytical Specificity | Not affected by common interferents; specific for total beta hCG subunit | Not affected by the addition of potential interferents (biological compounds and therapeutic agents found routinely in blood). Not affected by potential cross-reactants (hLH, hFSH, hTSH). Specific for total beta hCG subunit present as intact hCG or free beta subunit. |
| Linearity | Wide dynamic range for hCG measurement | Confirmed dynamic ranges of 5 to 10,000 mIU/mL for hCG. |
| Accuracy (Venous Blood vs. Predicate) | High correlation with predicate device | Based on 96 samples, the linear regression equation was y = 0.92x + 20 with a Correlation Coefficient of 0.98. This indicates very high agreement with the predicate. |
| Accuracy (Fingerstick Blood vs. Predicate) | High correlation with predicate device | Based on 63 samples, the linear regression equation was y = 1.05x + 8 with a Correlation Coefficient of 0.96. This indicates high agreement with the predicate. |
| Accuracy (DRx® Venous vs. DRx® Fingerstick) | High correlation between sample types | Based on 63 samples, the linear regression equation was y = 1.06x - 6 with a Correlation Coefficient of 0.99. This demonstrates strong equivalence between venous and fingerstick whole blood samples when tested on the DRx® Qt. hCG device. |
| Precision | Acceptable coefficients of variation (CV%) | The coefficients of variation ranged from 8.3% to 15.1% across three sites when tested with a 3-level whole blood precision panel (low, middle, and high hCG levels) on a single day. The specific "acceptable" range is not given, but these values are presented as evidence of suitable precision for point-of-care devices in this context. |
2. Sample Sizes Used for the Test Set and Data Provenance:
- Accuracy (Venous Blood vs. Predicate): 96 venous whole blood samples.
- Accuracy (Fingerstick Blood vs. Predicate): 63 matched whole blood capillary (fingerstick) samples.
- Accuracy (DRx® Venous vs. DRx® Fingerstick): 63 matched venous and fingerstick samples (implicitly the same 63 used for the fingerstick vs. predicate comparison, as they were "matched").
- Precision: Not explicitly stated as a single number per level, but tested with a "3-level whole blood precision panel" (low, middle, and high hCG levels) by repeat testing on a single day.
- Data Provenance:
- For accuracy studies, samples were collected at "four 'POL' clinical sites and in-house" for venous samples, and at "clinical sites" for fingerstick samples. This indicates the data is prospective and collected from multiple real-world clinical settings.
- The country of origin is not explicitly stated, but given the submission is to the FDA in the US, it is reasonable to assume the clinical sites were located within the US.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts:
The ground truth for the accuracy studies was established by comparison to a predicate device, the Stratus® ßhCG, not by expert consensus. Therefore, the concept of "number of experts" or their qualifications for establishing ground truth does not directly apply here. The predicate device's results serve as the reference.
4. Adjudication Method for the Test Set:
Not applicable, as the ground truth was established by a single, commercially available predicate device (Stratus® ßhCG) which served as the reference method. There was no expert adjudication process described for reconciling discrepancies.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done:
No, an MRMC comparative effectiveness study was not done. The study focused on the device's analytical performance (accuracy, precision, sensitivity, linearity, specificity) compared to a predicate device, and the equivalence of different sample types (venous vs. fingerstick), not on the improvement of human readers with AI assistance. The DRx® Qt. hCG is a standalone diagnostic device, not an AI-assisted interpretation tool for human readers.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done:
Yes, a standalone performance study was done. The DRx® Qt. hCG is described as "a rapid, single-use, point-of-care device for the quantitative measurement," indicating it provides a direct numerical result without human interpretation of images or complex data that would involve a "human-in-the-loop." The study evaluates the device's output (hCG concentration) directly against a predicate method.
7. The Type of Ground Truth Used:
The ground truth for the accuracy assessment was established using comparison to a legally marketed predicate device (Stratus® ßhCG). This is a common method for demonstrating substantial equivalence in medical device submissions where an established gold standard instrument exists.
8. The Sample Size for the Training Set:
The document does not specify a separate "training set" size. This type of submission (510(k) summary for a diagnostic device) typically focuses on the validation of the finalized device. The device's internal calibration parameters are mentioned ("Based on the calibration parameters stored in memory"), implying that some data was used for initial development and calibration, but the size and nature of this "training set" are not detailed in this summary.
9. How the Ground Truth for the Training Set was Established:
As the document does not explicitly mention a "training set" in the context of machine learning or AI, the concept of establishing ground truth for it as typically understood is not applicable. The device relies on "calibration parameters stored in memory" which would have been established through a manufacturing and calibration process, likely using known concentration standards, rather than expert-labeled data for training an algorithm.
§ 862.1155 Human chorionic gonadotropin (HCG) test system.
(a)
Human chorionic gonadotropin (HCG) test system intended for the early detection of pregnancy —(1)Identification. A human chorionic gonadotropin (HCG) test system is a device intended for the early detection of pregnancy is intended to measure HCG, a placental hormone, in plasma or urine.(2)
Classification. Class II.(b)
Human chorionic gonadotropin (HCG) test system intended for any uses other than early detection of pregnancy —(1)Identification. A human chorionic goadotropin (HCG) test system is a device intended for any uses other than early detection of pregnancy (such as an aid in the diagnosis, prognosis, and management of treatment of persons with certain tumors or carcinomas) is intended to measure HCG, a placental hormone, in plasma or urine.(2)
Classification. Class III.(3)
Date PMA or notice of completion of a PDP is required. As of the enactment date of the amendments, May 28, 1976, an approval under section 515 of the act is required before the device described in paragraph (b)(1) may be commercially distributed. See § 862.3.