(61 days)
Affirm One-Step home pregnancy test is a rapid one-step visual test for the qualitative detection of human chorionic gonadotropin in human urine to aid in the diagnosis of pregnancy. This test is intended for over-the-counter home use.
Affirm detects the presence of hCG in urine by using a combination of polyclonal and monoclonal antibodies on the reagent pad and the test strip. The assay begins functioning with the addition of urine onto the absorbent wick. Through capillary action the urine is pulled along the membrane to the reagent pad where the hCG reacts with the conjugate. Positive results are determined by one color line in the test window and one color line in the control window. The absence of hCG produces only one color line in the control window.
Here's an analysis of the provided text regarding the Affirm One-Step home pregnancy test, structured according to your request:
In this case, the acceptance criteria are largely implied rather than explicitly stated with numerical targets for specificity, sensitivity, and accuracy. The study aims to demonstrate that the device performs comparably to a predicate device and effectively detects hCG at a specified concentration.
1. Table of Acceptance Criteria and Reported Device Performance
| Acceptance Criteria Category | Implied Acceptance Criteria (from text) | Reported Device Performance |
|---|---|---|
| Specificity (Cross-reactivity) | No cross-reactivity with LH, FSH, and TSH at specified concentrations. | "Affirm did not cross-react with these substances [LH, FSH, TSH] at these levels [300mIU/ml LH, and 1000mIU/ml FSH and TSH]." (Only showed positive when 25mIU/ml hCG was also present). |
| Sensitivity (Analytical) | Detect hCG at a clinically relevant concentration (e.g., 25mIU/ml) within the specified timeframe. | "The 20 samples tested at the 25mlU/ml concentration all generated a positive reading well within the 20 minutes, therefore our claim is a 25mlU/ml sensitivity with the Affirm One-Step home pregnancy test. Even though the test is sensitive enough to read concentrations lower than 25mIU/ml this does not occur regularly for us to claim a lower sensitivity for the test." (Also noted: 5/20 samples positive at 10mIU/ml after 15 mins). |
| Accuracy (Analytical) | Consistent and correct detection of hCG at varying concentrations. | At 25, 50, and 100 mIU/ml hCG, all 20 samples tested positive (100% accuracy at these concentrations). At 0 mIU/ml hCG, all 20 samples tested negative (100% accuracy). At 10 mIU/ml hCG, 5 out of 20 samples tested positive (25% accuracy for positive-detection at this concentration). |
| Interfering Substances | No interference from common substances at specified concentrations. | "NONE" reported for Acetaminophen (20 mg/dI), Acetylsalicylic Acid (20 mg/dI), Ascorbic Acid (20 mg/dI), Atropine (20 mg/dI), Caffeine (20 mg/dI), Gentisic Acid (20 mg/dI), Glucose (2 mg/dI), Hemoglobin (200 mg/dI) in both hCG negative and 25 mIU/ml hCG spiked samples. |
| Predicate Device Correlation | High concordance with a legally marketed predicate device (SAS™ Pregnancy Strip). | "Both the Affirm One-Step home pregnancy test and the SAS™ Pregnancy Strip identified 54 true positives and 46 true negatives generating a 100% sensitivity for the Affirm One-Step home pregnancy test." (Implies 100% agreement on true positives and true negatives, and thus 100% specificity for the "true negatives" as well, though not explicitly stated as such). |
2. Sample Size Used for the Test Set and Data Provenance
- Specificity Test: The sample size is not explicitly stated as unique samples for LH, FSH, and TSH, but 25 mIU/ml hCG was tested simultaneously. It implies that at least one sample for each substance was tested.
- Sensitivity and Accuracy (Analytical): 20 negative urine samples were used, which were then "spiked with hCG at varying levels." This means 20 samples were tested at each concentration level: 10mIU/ml, 25mIU/ml, 50mIU/ml, 100mIU/ml, and 0mIU/ml.
- Interfering Substances: For each of the 8 interfering substances, samples were tested both with and without 25 mIU/ml hCG. The specific number of samples for each substance is not given, but it implies at least one sample for each condition.
- Predicate Device Result Correlation: 100 specimens.
- Data Provenance:
- Analytical studies (Specificity, Sensitivity, Accuracy, Interfering Substances): The text does not explicitly state the country of origin but references "spiked" samples, indicating these were laboratory-controlled rather than collected from patients directly.
- Predicate Device Result Correlation:
- Country of Origin: Not explicitly stated, but "clinics around town" and "Planned Parenthood in either Southeast Portland or Beaverton" (Oregon, USA) suggest the data is from the United States.
- Retrospective or Prospective: Prospective. The women were "solicited by a flyer" and asked to participate.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications
- Analytical Studies (Specificity, Sensitivity, Accuracy, Interfering Substances): For spiked samples (known concentrations of hCG, LH, FSH, TSH, and interfering substances), the "ground truth" is established by the laboratory's precise control over the spiked concentrations. No human experts are typically used to establish ground truth in this context; it's based on biochemical assays and measurements.
- Predicate Device Result Correlation: The ground truth for the 100 specimens (54 true positives and 46 true negatives) is implied to be established by the predicate device itself (SAS™ Pregnancy Strip), which is used as the reference test. No explicit number of experts or their qualifications are mentioned for establishing the "true positive" or "true negative" status of these clinical samples beyond the performance of the predicate device.
4. Adjudication Method for the Test Set
- None explicitly stated. For the analytical studies, the results are directly read from the device and compared to the known spiked concentrations. For the predicate device correlation, it's a direct comparison of the Affirm device's result to the SAS™ Pregnancy Strip's result for each specimen. There's no mention of multiple readers or an adjudication process for discrepancies.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
- No. This type of study (MRMC) is not mentioned or described. The study focuses on the device's standalone performance and its comparison to a predicate device, not on how human readers' performance improves with or without AI assistance. This device is a home-use, over-the-counter diagnostic test, not a system designed to assist healthcare professionals in interpretations.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
- Yes. The entire performance evaluation for the Affirm One-Step home pregnancy test is a standalone assessment. It's a consumer-use device where the user reads the visual result directly from the test strip without any "human-in-the-loop" decision support from an algorithm. The reported performance characteristics (specificity, sensitivity, accuracy, interference, and correlation study) all reflect the device's inherent capability to detect hCG.
7. The Type of Ground Truth Used
- Analytical Studies (Specificity, Sensitivity, Accuracy, Interfering Substances): Laboratory-controlled spiked concentrations of hCG and other substances. This represents a highly controlled, synthetic form of ground truth.
- Predicate Device Result Correlation: The results from the SAS™ Pregnancy Strip were used as the reference standard (ground truth) for the 100 clinical specimens.
8. The Sample Size for the Training Set
- This information is not provided in the summary. Pregnancy tests like this are typically developed through biochemical and immunoassay research and optimization, rather than machine learning models that require labeled training sets in the computational sense. The "training" would involve optimizing antibody concentrations, membrane types, and reaction conditions.
9. How the Ground Truth for the Training Set Was Established
- This information is not provided as there isn't a conventional "training set" in the machine learning sense for this type of device. The development process would have involved establishing optimal performance characteristics through experimental design, using known concentrations of analytes (hCG, interfering substances) in the laboratory. The ground truth for this optimization would be based on the accurate measurement of these analytes in controlled laboratory settings.
§ 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.