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PT/INR Home Testing

Quality Control Systems

Fail-Safe Mechanisms for Enhanced Accuracy & Safty

The CoaguChek XS system technology was developed to provide a very high level of quality, accuracy, and patient safety. All of the system components have been manufactured to rigorous quality standards and subjected to extensive stability testing.

However, it is always possible for abuse, accidents, or unexpected electronic component failures to affect the meter’s operation and potentially lead to inaccurate results.

As a result, the CoaguChek XS system includes many fail-safe mechanisms to detect potential strip and meter problems. These extra quality checks work in conjunction with the device’s onboard controls to ensure that the system provides anticoagulation monitoring results that patients and healthcare professionals can trust.4

Power-On Self-Tests
As the meter powers up, all the basic functions that are necessary to run the prothrombin time (PT) test are checked. In addition to the basic meter configuration, which was set during production, the meter software and all internal data memories are checked. This ensures that neither software nor other internal data, including the result memory, are corrupted for any reason. The meter also confirms that the power supply conditions are correct.

For additional protection, a separate electronic network checks the electronic components of the complete measurement path (similar to the function of an “electronic quality control” device). In the case of defects, an error message is displayed and measurement is no longer possible.

Measurement Preparation Tests
Prior to the test strip being inserted, the meter checks the position of the test strip/ measurement chamber cover, as well as the ambient temperature.

If the temperature is outside of the specified range, an error message is displayed and a test cannot be run.

Once the test strip is inserted, the user also has to confirm, by pressing a button, that the code number of the strip lot displayed in the device matches the code number of the strip vial. This ensures that test results are converted into correctly calibrated INR values, using the code chip data that corresponds to the strip lot used in the meter.

Device Performance Tests
After the confirmation of the correct test strip lot, the code chip type and its contents are checked. Any data transfer from the code chip into internal memories is safeguarded by a cyclic redundancy check (CRC) to detect any data corruption.

Additional checks are performed during this phase to ensure proper functionality of the test strip/meter interface and the test strip itself. The time base of the microcontroller is also checked by an additional independent time base (clock). In case of any defects in the clock, an error message is displayed.

After this phase, the system is ready for sample application. As many checks as possible are performed before a sample is applied in order to conserve test strips and prevent unnecessary blood sampling.

Strip Integrity and Sample Tests
After sample application, the fill detect system will indicate that an adequate sample has been applied to the test strip. A new and innovative fail-safe feature – the integrated Onboard Quality Control (OBC) system – checks each test strip for mishandling, in the same chamber where the actual patient PT test is performed.

The system detects any kind of strip mishandling – such as improper storage in a hot, humid environment or exposure to extended ambient light. In the case of mishandled strips, the device will display a QC error and not provide a test result. During the test run, the system also checks all important fail-safe features periodically.

Measurement Result Tests
At the end of the prothrombin time measurement process, the raw test data are converted into calibrated INR values and checked within the specified measurement range of the system.
If a therapeutic range was set for the individual patient, the system checks whether the INR values are within the specified range. Values outside the predefined range are displayed with an arrow.

Exclusive smart technology for confidence in your results

The CoaguChek XS System is the only system to perform onboard quality control and determine patient results in a single test chamber–ensuring that every test strip is checked in the area where the actual patient test occurs.1,2

The PT/INR test principle
The CoaguChek XS PT Test Strip uses a human recombi¬nant thromboplastin with a 1.0 ISI and a peptide substrate. The enzyme thrombin (factor IIa) cleaves the peptide sub¬strate, generating an electrochemical signal. The system converts this signal into INR by means of an algorithm and then displays the result.

Two-level onboard quality control in a single chamber
Built-in quality control enables the CoaguChek XS System to automatically confirm meter performance and proper strip chemistry (Level I) and check patient test strips for mishandling (Level II). A special “misuse detector” in the strips – the chemical Resazurin – detects exposure to high humidity, extreme temperature and other environmental factors that could affect strip integrity.

These quality control tests are performed on every single strip in the exact physical and chemical environment where the patient test results are determined.

• Checks quality of every patient test strip
• Validates strip integrity where patient test reaction occurs
• Provides exceptionally reliable detection of defects3

1 CoaguChek XS System package insert. Indianapolis, IN. Roche Diagnostics Corporation, 2006.
2 INRatio System package insert. Milpitas, CA. HemoSense Inc., 2003. ProTime System package insert. Edison, NJ. ITC, 2006.
3 In performance studies, zero unreliable INR results were reported due to QC failure. Data on file.
4 CoaguChek XS package insert and data on file. Indianapolis, IN. Roche Diagnostics Corporation, 2006.
5 Year-end 2008 data as reported in first quarter 2009, total dollar volume and share of projected distributor unit sales of the Coagulation Reagents/Kits, POC
(91994) by GHX Market Intelligence Data. Total Market includes all market sectors as defined by GHX MI. Physician, LTC, Treatment Centers, Clinical Laboratory,
Hospital, Home Healthcare, and Other/Unspecified. Data on file at Roche Diagnostics.

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