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For quantitative prothrombin time testing in fresh capillary blood with the CoaguChek System by properly selected and suitably trained patients or their caregivers on the prescription or other order of the treating doctor.

The CoaguChek PT.S Test is for quantitative prothrombin time testing in fresh capillary blood with the CoaguChek System by properly selected and suitably trained patients or their caregivers on the prescription or other order of the treating doctor.

Blood coagulation is one of the body's protective responses. Blood clots (thrombi) form as a direct response to vessel injury, preventing excessive loss of blood. Certain disease conditions require oral anticoagulants, sometimes known as blood thinners. Warfarin, sometimes known as Coumadin®, is a commonly used anticoagulant. Patients on warfarin must be carefully monitored to ensure the anticoagulant level is maintained in the therapeutic range. One method for monitoring the anticoagulant level is by using the one-stage Prothrombin Time (PT) Test. The PT.S test strip uses a modified version of this method.

The PT.S test strip, used as directed with the CoaguChek monitor, will accurately measure blood PT values. After placing a drop of fresh whole blood on the test strip, the blood is drawn into the reaction chamber and mixed with reagents that cause coagulation to begin. In the test strip, tiny iron particles are mixed with the sample. Alternating magnetic fields cause the iron particles to move within the sample. The endpoint is reached when the blood clot stops the iron particles from moving. The PT result is then displayed by the monitor.

Here's a breakdown of the acceptance criteria and study information for the CoaguChek™ PT•S Test for Prothrombin Time Self-Testing, based on the provided text:

Acceptance Criteria and Device Performance

Note: The document presents the predicate device's performance as the benchmark for "acceptance criteria" through substantial equivalence. The new device's performance is listed alongside for comparison.

Study Information

The provided document describes a substantial equivalence comparison study against a predicate device (K962571), rather than a standalone clinical trial with explicitly defined "acceptance criteria" and "study proving it." The information below is extracted based on the nature of this submission.

2. Sample Size and Data Provenance:

• Test Set Sample Size:
  • Accuracy: 84 observations
  • Precision (Patient Results): 841 observations
  • Precision (Professional Results): 140 observations
• Data Provenance: Not explicitly stated (e.g., country of origin, retrospective/prospective). However, the device is for "patient self-testing" and "professional results," implying data collected from actual patient and professional use, likely in a clinical setting. The submission date (March 2003) and 510(k) approval (May 2003) suggest the data was collected retrospectively to support the submission or as part of a prospective study leading up to it.

3. Number of Experts and Qualifications for Ground Truth:

• Not applicable/Not specified. The ground truth for prothrombin time (PT) tests is typically established by laboratory reference methods, not by expert consensus on visual review or interpretation. The document compares the device's measurements to another established method.

4. Adjudication Method:

• Not applicable/Not specified. Adjudication methods like 2+1 or 3+1 typically apply to studies where human interpretation (e.g., of medical images) requires consensus. For a quantitative diagnostic test like PT, the "ground truth" is a numerical value derived from a reference method, not subject to human adjudication in that manner.

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

• No, an MRMC comparative effectiveness study was not done. This type of study is relevant for evaluating the impact of AI assistance on human reader performance, typically in imaging diagnostics. The CoaguChek™ PT•S Test is a quantitative diagnostic test performed by a device, not a human reader interpreting complex information.

6. Standalone (Algorithm Only) Performance:

• Yes, the performance data presented (accuracy and precision) represents the standalone performance of the CoaguChek™ PT•S Test strip and CoaguChek monitor system. The device produces a direct numerical result (PT/INR) without human interpretation in the loop. The "professional results" and "patient results" for precision indicate testing done by different user groups, but both represent the device's output.

7. Type of Ground Truth Used:

• The ground truth is quantitative prothrombin time (PT) values obtained from a reference method or legally marketed predicate device (CoaguChek System K962571). The accuracy data, which compares the new device's slope, intercept, and correlation coefficient, suggests a comparison against an existing, validated PT measurement method.

8. Sample Size for the Training Set:

• Not applicable/Not specified. The CoaguChek™ PT•S Test is a diagnostic test based on a chemical reaction and mechanical detection (iron particle movement), not a machine learning algorithm that requires a training set.

9. How the Ground Truth for the Training Set Was Established:

• Not applicable/Not specified, as there is no "training set" for this type of device.

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