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Afinion™ ACR is an in vitro diagnostic test for quantitative determination of albumin, creatinine and albumin/creatinine ratio (ACR) in human urine. The measurement of urine albumin, creatinine and albumin/creatinine ratio aids in the early diagnosis of nephropathy.

Afinion™ ACR Control is a assayed in vitro diagnostic quality control material used to confirm that the Afinion™ ACR and the Afinion™ AS100 Analyzer System is working properly and provides reliable results

The Afinion™ ACR assay is an in vitro diagnostic test for quantitative determination of albumin, creatinine and albumin/creatinine ratio (ACR) in human urine using the Afinion™ AS100 Analyzer. The measure of urine albumin aids in the early diagnosis of nephropathy.

The Afinion™ ACR Control kit contains liquid preparations of albumin and creatinine in citrate buffer. The controls should be used to confirm that the Afinion™ AS100 Analyzer System is working properly and provides reliable results.

Afinion™ ACR is a fully automated assay for determination of albumin, creatinine and albumin/creatinine ratio (ACR) in human urine.

The Afinion™ ACR Test Cartridge contains all the reagents necessary for determining albumin, creatinine and ACR in a human urine sample. The sample material is sampled using the sampling device integrated into the Test Cartridge.

Albumin is quantified using a solid phase immunochemical assay. In the Afinion™ ACR Test Cartridge the sample is automatically diluted and aspirated through a membrane coated with antialbumin antibodies, which concentrates and immobilizes the albumin from the sample. A goldantibody conjugate then binds to the immobilized albumin resulting in a red-brown stained membrane. Excess gold-antibody conjugate is removed in a washing step. The Afinion™ AS100 Analyzer measures the color intensity of the membrane, which is proportional to the amount of albumin in the sample.

Creatinine is quantified using an enzymatic colorimetric test that involves four enzymatic steps. The test requires incubation with two distinct enzyme solutions. A colored end product is measured in one of the cartridge wells.

The concentration of albumin, the concentration of creatinine, and the calculated albumin/creatinine ratio are displayed on the Afinion™ AS100 Analyzer.

Acceptance Criteria and Study Details for Afinion™ ACR

1. Acceptance Criteria and Reported Device Performance

The acceptance criteria for the Afinion™ ACR assay were implicitly established through its comparison to a legally marketed predicate device, the DCA 2000® Microalbumin/Creatinine assay (K963142). The goal was to demonstrate "substantial equivalence" in performance. While explicit numerical acceptance criteria were not provided in terms of thresholds for correlation coefficients or precision values, the reported device performance, demonstrating strong correlation and acceptable precision, was considered sufficient to meet the equivalence standard.

2. Sample Size and Data Provenance

• Test Set (Method Comparison - External Study):

  • Sample Size: 169 urine samples
  • Data Provenance: Studies were conducted at "four external study sites." The specific country of origin is not explicitly stated, but the submission is from Norway, hence it's likely European or international. The samples were retrospective, as they were "analyzed" with both devices.

• Test Set (Method Comparison - Internal Study):

  • Sample Size: 91 urine samples for Albumin and ACR, 95 urine samples for Creatinine.
  • Data Provenance: "Internal method comparison study," implying the data originated from the manufacturer's own facilities. These were retrospective samples.

• Test Set (Precision Study):

  • Sample Size: Not explicitly stated as a number of unique patient samples for the clinical precision study. Instead, it refers to "two levels of urine samples" (Sample 1 and Sample 2) run multiple times. For the control precision, controls were run in "6 replicates each day over 5 operating days."
  • Data Provenance: "External precision study" and "3 study sites" for controls.

3. Number of Experts and Qualifications for Ground Truth

The study relies on comparing the performance of the new device against a predicate device (DCA 2000® Microalbumin/Creatinine assay). Therefore, the "ground truth" for the test set is effectively the result obtained from the predicate device. No human experts were used to establish a separate, independent ground truth for the test samples in this specific type of comparison study. The predicate device itself acts as the reference standard.

4. Adjudication Method

Not applicable. Since the ground truth for comparison was the result from a predicate device, and the study focused on quantitative correlation and precision, there was no need for expert adjudication of results.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. This submission is for an in vitro diagnostic (IVD) device, specifically an automated assay for quantitative measurement. This type of study is more common for imaging devices or those requiring human interpretation of results. The study design focuses on the analytical performance (accuracy, precision) of the device itself compared to a predicate device, not on how human readers' diagnostic performance might improve with or without AI assistance.

6. Standalone (Algorithm Only) Performance

Yes, the study describes the standalone performance of the Afinion™ ACR assay. It is an "automated assay" that "quantifies" albumin and creatinine, and "calculates" the ACR. The performance metrics (correlation coefficients, precision) presented are solely based on the device's measurements from urine samples, without human intervention in the result generation or interpretation to modify the output.

7. Type of Ground Truth Used

The "ground truth" used for evaluating the Afinion™ ACR assay was the results obtained from a legally marketed predicate device, the DCA 2000® Microalbumin/Creatinine assay (K963142). This is a common approach for demonstrating substantial equivalence for in vitro diagnostic devices. It relies on the established accuracy and reliability of the predicate.

8. Sample Size for the Training Set

The document does not explicitly mention a separate "training set" or its sample size in the context of device development. For IVD assays, development often involves extensive internal testing, calibration, and optimization using various samples, but this is usually distinct from the formal "training set" concept seen in AI/machine learning development.

9. How Ground Truth for the Training Set was Established

Given that this is an in vitro diagnostic assay and not a machine learning algorithm in the typical sense, there isn't a "training set" with ground truth established in the way one would for an AI model.

The "standardization" section states that:

• Albumin is calibrated against the ERM®-DA470 reference preparation.
• Creatinine is calibrated against SRM 914a.

These reference materials serve as the foundational "ground truth" for the device's calibration, ensuring that its measurements are traceable to recognized international standards. This calibration process, along with extensive internal testing and optimization (which would involve numerous samples with known values, likely determined through reference methods or predicate devices), forms the basis of the device's accuracy.

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