Diagnostic kit with a memory storing test strip calibration codes and related methods

• US 6,780,645 B2
• Filed: 08/21/2002
• Issued: 08/24/2004
• Est. Priority Date: 08/21/2002
• Status: Expired due to Term

• Current Assignee: Cilag Gmbh International (Johnson & Johnson)
• Original Assignee: Lifescan Incorporated (Duv Holding Corporation)
• Inventors: Hayter, Paul G., Ohara, Timothy J., Sharma, Manoj K., Aquino, Maria, Poulos, Darwin
• Primary Examiner(s): WALLENHORST, MAUREEN
• Application Number:
  US10/224,888
• Publication Number:
  US 20040038411A1
• Time in Patent Office: 734 Days
• Field of Search: 436/8, 436/14, 436/16, 436/63, 436/69, 436/164, 422/61, 422/55, 422/58, 422/73, 435/13, 435/14, 435/810, 702/19, 702/22, 702/23, 702/32, 703/11, 703/12, 73/10.1, 73/10.3
• US Class Current: 436/8
• CPC Class Codes: G01N 33/48771 Coding of information, e.g. calibration data, lot number
• CPC Class Codes: Y10T 436/10 Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
• CPC Class Codes: Y10T 436/104998 Glucose, ketone, nitrate standard or control

Abstract

A diagnostic kit for measuring a characteristic of a fluid sample includes a test strip (e.g., a disposable blood glucose test strip) and device (e.g., a hand-held meter) for measuring a property (e.g., an optical or electrochemical property) of the test strip. The device also calculates, based on the measured property of the test strip, a characteristic (e.g., blood glucose concentration or INR) of a fluid sample applied to the test strip. Stored in a memory of the device are test strip calibration codes that represent geometric regions (e.g., polygonal or hexagonal geometric regions) of a multi-dimensional calibration parameter space. The test strip calibration codes and geometric regions are distributed across the multi-dimensional calibration parameter space such that a quantization error of assigning one of test strip calibration codes to the test strip is optimally reduced. Also, a method for optimally associating test strip calibration codes to calibration parameters for use in such a diagnostic kit that includes first optimally distributing a plurality of test strip calibration codes and geometric regions represented thereby across a multi-dimensional calibration parameter space. The distribution is conducted such that a quantization error of assigning one of the test strip calibration codes to the test strip of the diagnostic kit is optimally reduced. The method also includes storing the distributed test strip calibration codes in a memory of the diagnostic kit.

Claims

1. A diagnostic kit for measuring a characteristic of a fluid sample, the diagnostic kit comprising:

a test strip with a test strip calibration code assigned thereto; and

a device for measuring at least one property of the test strip and calculating, therefrom, a characteristic of a fluid sample applied to the test strip, the device including;

a memory with a plurality of test strip calibration codes, including the test strip calibration code assigned to the test strip, stored therein, wherein each of the test strip calibration codes in the memory are mathematically manipulated in the device to represent a geometric region of a calibration parameter space, wherein the geometric regions are formed by a boundary of a set of points representing values of calibration parameters of maximum permissible error, and wherein the test strip calibration codes and geometric regions are distributed across the calibration parameter space such that a quantization error of having assigned the test strip calibration code to the test strip is optimally reduced.

2. The diagnostic kit of claim 1, wherein each of the test strip calibration codes represents a geometric region of a multi-dimensional calibration parameter space.

3. The diagnostic kit of claim 1, wherein the test strip is a disposable blood glucose test strip and wherein the device employs an algorithm of the simplified form:

4. The diagnostic kit of claim 3, wherein the test strip calibration codes are distributed across the two-dimensional p-Z calibration parameter space based on optimization using constant error equations.

5. The diagnostic kit of claim 3, wherein the test strip calibration codes represent one of hexagonal geometric regions and partial hexagonal geometric regions of the two-dimensional p-Z calibration parameter space.

6. The diagnostic kit of claim 5, wherein the test strip calibration codes are distributed across the two-dimensional conceptual p-Z calibration parameter space using an incremental resolution based on the 95^th percentiles of a calibration parameter calibration error.

7. The diagnostic kit of claim 1, wherein the test strip is an International Normalization Ratio (INR) test strip and wherein the device employs an algorithm of the form:

$\mathrm{INR}={\left(\frac{\mathrm{PT}}{\mathrm{MNPT}}\right)}^{\mathrm{ISI}}$

where;

PT is a prothrombin time measured by the device; and

MNPT and ISI are calibration parameters

to calculate INR and wherein the test strip calibration codes represent polygonal geometric regions of a two-dimensional MNPT-ISI calibration parameter space.

8. The diagnostic kit of claim 7, wherein the test strip calibration codes represent stepped polygonal geometric regions of the two-dimensional ISI-MNPT calibration parameter space.

9. The diagnostic kit of claim 8, wherein the stepped polygonal geometric regions are comprised of a plurality of adjacent parallelograms.

10. The diagnostic kit of claim 1, wherein the memory stores a plurality of test strip calibration codes that optimally reduce the quantization error by maintaining predetermined quantization error limits with a minimum number of test strip calibration codes.

11. The diagnostic kit of claim 10, wherein the predetermined quantization error limits are based on an accuracy requirement of the diagnostic kit.

12. The diagnostic kit of claim 1, wherein each of the test strip calibration codes represents one of a hexagonal geometric region or a partial hexagonal geometric region of a two-dimensional calibration parameter space.

13. The diagnostic kit of claim 1, wherein the memory stores a plurality of test strip calibration codes distributed such that each of the test strip calibration codes represent a polygonal geometric region of a two-dimensional calibration parameter space.

14. The diagnostic kit of claim 13, wherein the polygonal geometric region is a stepped polygonal geometric region comprised of a plurality of adjacent parallelograms.

15. The diagnostic kit of claim 1, wherein the test strip is a disposable blood glucose test strip and the device is a hand-held meter for measuring an optical property of the disposable blood glucose test strip.

16. The diagnostic kit of claim 1, wherein the test strip is a disposable blood glucose test strip and the device is a hand-held meter for measuring an electrochemical property of the disposable blood glucose test strip.

17. The diagnostic kit of claim 1, wherein the test strip is a prothrombin test strip and the device is a device for measuring optical properties of the prothrombin test strip.

18. The diagnostic kit of claim 1, wherein the test strip calibration codes are distributed across the calibration parameter space further using a geometric pattern that is dependent on an objective function that defines overall test strip calibration error.

19. The diagnostic kit of claim 1, wherein the device is a hand-held meter.

20. The diagnostic kit of claim 1, wherein the fluid sample is a physiological fluid sample.

21. A method for optimally associating test strip calibration codes to calibration parameters for use in a diagnostic kit that includes a test strip, with a test strip calibration code assigned thereto, and a device with a memory, the method comprising:

mathematically manipulating a plurality of test strip calibration codes, including the test strip calibration code assigned to the test strip, in the device to represent geometric regions of a calibration parameter space, wherein the geometric regions are formed by a boundary of a set of points representing values of calibration parameters of maximum permissible error,

distributing said plurality of test strip calibration codes and geometric regions represented by the test strip calibration codes across said calibration parameter space such that a quantization error of having assigned the test strip calibration code to the test strip is optimally reduced, thereby associating the test strip calibration codes with calibration parameters of the calibration parameter space; and

storing the test strip calibration codes thus distributed in the memory of the device.

22. The method of claim 21, wherein the distributing step distributes the test strip calibration codes across a multi-dimensional calibration parameter space.

23. The method of claim 21, wherein the distributing step distributes a plurality of test strip calibration codes that represent one of a hexagonal geometric region or a partial hexagonal geometric region of a two-dimensional calibration parameter space.

24. The method of claim 21, wherein the distributing step distributes a plurality of test strip calibration codes that represent polygonal geometric regions of a two-dimensional calibration parameter space.

25. The method of claim 24, wherein the distributing step distributes a plurality of test strip calibration codes that are associated with stepped polygonal geometric regions of a two-dimensional calibration parameter space.

26. The method of claim 21, wherein the distributing step distributes a plurality of test strip calibration codes by optimally reducing the quantization error based on an objective function related to performance of the diagnostic kit.

27. The method of claim 21, wherein the distributing step distributes a plurality of test strip calibration codes by optimally reducing the quantization error based on a Mean Absolute Bias (MAB) objective function.

28. The method of claim 21, wherein the distributing step distributes a plurality of test strip calibration codes by optimally reducing the quantization error based on constant error objective functions related to performance of the diagnostic kit.

29. The method of claim 21, wherein the distributing step distributes a plurality of test strip calibration codes by optimally reducing the quantization error based on a Mean Absolute Relative Deviation (MARD) objective function.

30. An assay kit for analyzing a sample, the assay kit comprising:

a reagent; and

an analytical device employed in conjunction with the reagent to carry out a predetermined analysis of the sample, the analytical device including;

a memory with a plurality of reagent calibration codes stored therein, wherein each of the reagent calibration codes in the memory are mathematically manipulated in the device to represent a geometric region of a calibration parameter space, wherein the geometric regions are formed by a boundary of a set of points representing values of calibration parameters of maximum permissible error, and wherein the reagent calibration codes and geometric regions are distributed across the calibration parameter space such that a quantization error of having assigned one of the reagent calibration codes to the reagent is optimally reduced.

31. A method for optimally associating reagent calibration codes to calibration parameters for use in an assay kit that includes a reagent and an analytical device with a memory, the method comprising:

mathematically manipulating a plurality of reagent calibration codes in the device to represent geometric regions of a calibration parameter space, wherein the geometric regions are formed by a boundary of a set of points representing values of calibration parameters of maximum permissible error,

distributing said plurality of reagent calibration codes and geometric regions represented by the reagent calibration codes across said calibration parameter space such that a quantization error of having assigned one of the reagent calibration code to the reagent is optimally reduced, thereby associating the reagent calibration codes with calibration parameters of the calibration parameter space; and

storing the reagent calibration codes thus distributed in the memory of the analytical device.