(29 days)
The Chemtrue® hCG Pregnancy Urine Midstream Test is a rapid lateral flow qualitative immunoassay for early detection of human chorionic gonadotropin (hCG) in human urine in the device format of Midstream. The test is designed to aid early detection of pregnancy by home users. The device is intended for Over-The-Counter (OTC) Use.
The device employs lateral flow immunoassay technology for detection of human chorionic gonadotropin (hCG) in urine. Monoclonal goat anti-hCG antibodies are pre-striped in the nitrocellulose membrane on the test region (T line) and goat antibodies on the control region (C line). During testing, the urine/serum specimen reacts with the conjugate pad (It contains colloidal gold particles conjugated with monoclonal anti-hCG antibody specific to the beta subunit of hCG) located just beneath the sample pad and above the membrane of the test strip. The specimen migrates upward on the membrane by capillary action to react with the antibodies on the membrane. If the hCG concentration in the specimen is at or above the designated detection limit, a red colored line at the test region will be present indicating a positive result, while its absence indicates a negative result. The control line (C line) serves as an internal quality control. The control line should always appear, regardless of the hCG concentration of the test specimen, and the C line is an indicator that sufficient sample volume has been added to the test device and the sample has correctly migrated up the test strip.
The device is designed in Midstream format. Each device consists of one (1) individual test strip and each test strip in the device consists of:
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- A conjugate pad contains colloidal gold conjugated with monoclonal anti-hCG antibody specific to the beta subunit of hCG.
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- A nitrocellulose membrane which is striped with the specific goat anti-hCG in the test line (T line) and goat anti-mouse antibody in the control line (C line). Presence of this line indicates that the test is performed correctly. A test result is read at three (3) minutes and the cut-off of the device is 20 mIU/mL hCG.
The Midstream Test kit consists of one test device in a foil pouch and a package insert.
Here's a summary of the acceptance criteria and the study that proves the device meets them, based on the provided 510(k) summary:
Acceptance Criteria and Device Performance
| Acceptance Criteria Category | Specific Criteria | Reported Device Performance |
|---|---|---|
| Sensitivity (Cutoff) | Detect hCG at a specific cutoff concentration (20 mIU/mL). At 0 mIU/mL and 10 mIU/mL, no positive results. At 20 mIU/mL and above, 100% positive results. | * 0 mIU/mL: 0/15 positive (across 3 lots) |
- 10 mIU/mL: 0/15 positive (across 3 lots)
- 15 mIU/mL: 3/15 positive (some variability below cutoff, but mostly negative)
- 20 mIU/mL: 15/15 positive (across 3 lots)
- 40 mIU/mL: 15/15 positive (across 3 lots)
- 80 mIU/mL: 15/15 positive (across 3 lots)
Conclusion: Confirmed cutoff of 20 mIU/mL. |
| Reproducibility/Precision| Consistent functional performance across different sites and operators at various hCG concentrations. At 20 mIU/mL and above, 100% positive results. At 0 mIU/mL and 10 mIU/mL, 100% negative results. | * 0 mIU/mL: 0/27 positive (across 3 sites) - 10 mIU/mL: 0/27 positive (across 3 sites)
- 15 mIU/mL: 3/27 positive (showing some variability below cutoff)
- 20 mIU/mL: 27/27 positive (across 3 sites)
- 25 mIU/mL: 27/27 positive (across 3 sites)
- 30 mIU/mL: 27/27 positive (across 3 sites)
- 35 mIU/mL: 27/27 positive (across 3 sites)
Conclusion: Consistent functional performance between sites. |
| Analytical Specificity | No interference from structurally-related hormones (hLH, hFSH, hTSH), common exogenous compounds, β-core hCG fragment, varying pH, and specific gravity. | * hLH, hFSH, hTSH: No interference at specified concentrations (1000 IU/L FSH, 500 IU/L LH, 1000 IU/L TSH) for both negative (5mIU/mL hCG) and positive (50mIU/mL hCG) samples. - Exogenous Compounds: No interference observed at specified concentrations for 17 tested compounds (e.g., Acetylsalicylate Acid, Albumin, Ascorbic Acid, Glucose, Hemoglobin) for both negative (0mIU/mL hCG) and positive (20mIU/mL hCG) samples.
- β-core hCG fragment: No interference observed up to 1,000,000 pmol/mL for samples containing 5 mIU/mL and 50 mIU/mL hCG.
- pH: No interference observed over pH range 2.0 to 9.0 for 0 and 20 mIU/mL hCG.
- Specific Gravity: No interference observed over SG range 1.003 to 1.030 for 0 and 20 mIU/mL hCG. |
| High Dose/Hook Effect | No hook effect observed at high hCG concentrations. | No hook effect observed up to 500 IU/mL hCG. |
| Method Comparison | 100% agreement with the predicate device when tested by healthcare professionals. | 100% agreement (150 positive, 150 negative) with OSOM® Card II hCG-Urine Test. |
| OTC Lay-user Performance | 100% agreement between lay-users' results and HCPs' results. Lay-users should be able to correctly interpret results and find the test easy to use based on labeling. | * Agreement: 100% agreement between lay-user (midstream) and HCP (dip method) results (55 positive, 45 negative). - Cutoff confirmation by lay-users: 0/33 positive at 10 mIU/mL, 2/34 positive at 15 mIU/mL, 33/33 positive at 25 mIU/mL (similar to HCP results).
- Usability: Questionnaire results indicated consumers found the test easy to use and understood labeling. Flesch-Kincaid Grade Level 7 for labeling. |
| Stability | Device stable for a specified shelf-life. | Devices stable for 24 months when stored at 25±2ºC in a sealed foil pouch (supported by real-time and accelerated stability at 40°C and 60°C). |
Study Details
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Sample sizes used for the test set and the data provenance:
- Sensitivity: 15 replicates per hCG concentration level, across 3 lots (total 90 tests at key cutoff levels). Data provenance is not explicitly stated as retrospective vs. prospective, but based on the description of spiked samples and blind coding, it appears to be a prospective experimental study conducted by the manufacturer.
- Reproducibility (Precision): Not explicitly stated as a single "test set" size, but the study involved 9 operators in 3 POL sites, testing 8 hCG concentrations, across 3 lots, over 5 nonconsecutive days. This equates to 9 operators * 3 lots * 5 days * 8 concentrations = 1080 data points, though the table shows 9 tests per site * 3 sites = 27 tests per concentration level total. The data provenance is a prospective multi-site experimental study.
- Analytical Specificity:
- Hormones: Test performed with spiked hCG negative (5mIU/mL) and positive (50 mIU/mL) samples across 3 lots. Sample size for each hormone level is not explicitly stated but implies multiple replicates.
- Exogenous Compounds: Samples containing 0 and 20 mIU/mL hCG spiked with interferents, tested using 3 different lots. Sample size for each compound is not explicitly stated but implies multiple replicates (e.g., "samples were tested").
- β-core hCG fragment: 5 replicates from 3 lots (total 15 tests per hCG and fragment concentration combination).
- pH & Specific Gravity: Duplicate tests at each level for each test format.
- High Dose/Hook Effect: 5 replicates per hCG concentration level across 3 lots (total 75 tests).
- Method Comparison Study: 300 urine samples (100 women from each of 3 hospitals). Approximately half were suspected pregnant. Data provenance is prospective from "women presenting at three (3) hospitals to test for pregnancy." Likely domestic U.S. data given FDA 510(k).
- OTC Lay-user Study: 100 women for the natural urine samples, and 100 aliquots of spiked samples (for 10, 15, 25 mIU/mL hCG each). Data provenance is prospective, conducted at three (3) clinical sites in women with varied education backgrounds and ages 22-39. Likely domestic U.S. data.
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Number of experts used to establish the ground truth for the test set and the qualifications of those experts:
- Sensitivity, Reproducibility, Analytical Specificity, High Dose/Hook Effect: Ground truth was established by known concentrations of hCG or interferents added to urine pools, traceable to WHO International Standards. No human experts established ground truth for these analytical performance studies.
- Method Comparison Study: The predicate device, OSOM® Card II hCG-Urine Test (K990578), served as the reference standard (ground truth) for agreement. The results with the new device were compared to the results of the predicate device when used by healthcare professionals. The qualifications of these professionals are not detailed beyond "healthcare professionals."
- OTC Lay-user Study: The ground truth for the natural urine samples was established by the results obtained by healthcare professionals (HCPs) using the dip method with the Chemtrue® hCG device. For the spiked samples, the ground truth was the known spiked concentrations of hCG. The qualifications of these HCPs are not detailed beyond "healthcare professionals."
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Adjudication method (e.g. 2+1, 3+1, none) for the test set:
The document does not describe any formal adjudication method (like 2+1 or 3+1 consensus reading) for interpreting results in any of the studies.
- For the sensitivity and reproducibility studies, results were read by operators (e.g., "five (5) replicates were tested at each hCG control level by three (3) operators," "interpreted by the same operator each day"). Consistency across operators/lots/sites was checked.
- For method comparison, healthcare professionals read the proposed and predicate devices.
- For the lay-user study, lay-users interpreted their own test and HCPs interpreted their own test.
The primary assessment method appears to be direct observation of the visually-read line intensity by the designated individual(s).
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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, an MRMC comparative effectiveness study involving AI assistance was not done. The device is a visually-read, self-contained rapid diagnostic test, not an AI-powered diagnostic imaging or interpretation system. The "readers" are either healthcare professionals or lay-users interpreting a physical test strip, not an AI algorithm.
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If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:
No, a standalone algorithm-only performance study was not done. This device is a manual, visually-read test kit; it does not involve a digital algorithm.
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The type of ground truth used (expert consensus, pathology, outcomes data, etc.):
- Analytical Studies (Sensitivity, Reproducibility, Specificity, Hook Effect): The ground truth was known, traceable concentrations of hCG or interferents in urine matrix, calibrated against WHO International Standards. This is a form of analytical reference standard.
- Method Comparison Study: The ground truth was the results obtained from the predicate device (OSOM® Card II hCG-Urine Test), interpreted by healthcare professionals. This acts as a previously accepted reference method.
- OTC Lay-user Study: For patient samples, the ground truth was the results obtained from healthcare professionals using the new device. For spiked samples, it was the known concentrations of hCG in the spiked aliquots. This combines expert interpretation and analytical reference standard.
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The sample size for the training set:
The document does not describe training data or a training set because this device is a qualitative lateral flow immunoassay, not an AI/machine learning algorithm. Therefore, there is no "training set" in the context of AI.
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How the ground truth for the training set was established:
As there is no training set for an AI algorithm, this question is not applicable.
§ 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.