Method for determining analyte concentration based on complex index functions

• US 8,744,776 B2
• Filed: 06/06/2011
• Issued: 06/03/2014
• Est. Priority Date: 12/08/2008
• Status: Active Grant

• Current Assignee: Ascensia Diabetes Care Holdings AG (PHC Holdings Corporation)
• Original Assignee: Bayer Healthcare LLC (Bayer AG)
• Inventors: Wu, Huan-Ping, Jung, Sung-Kwon
• Primary Examiner(s): Whaley, Pablo S
• Application Number:
  US13/153,793
• Publication Number:
  US 20110297554A1
• Time in Patent Office: 1,093 Days
• Field of Search: None
• US Class Current: 702/19
• CPC Class Codes: G01N 27/3273 Devices therefor, e.g. test element readers, circuitry details not specific to biochemical electrodes G01N33/4875
• CPC Class Codes: G01N 27/3274 Corrective measures, e.g. error detection, compensation for temperature or hematocrit, calibration coding of calibration information G01N33/48771
• CPC Class Codes: G01N 27/416 Systems G01N27/27 takes precedence

Abstract

A biosensor system determines analyte concentration from an output signal generated from a light-identifiable species or a redox reaction of the analyte. The biosensor system adjusts a correlation for determining analyte concentrations from output signals or determined analyte concentrations with one or more complex index function extracted from the output signals or from other sources. The complex index functions determine at least one slope deviation value, ΔS, or normalized slope deviation from one or more error parameters. The slope-adjusted correlation between analyte concentrations and output signals may be used to determine analyte concentrations having improved accuracy and/or precision from output signals including components attributable to bias.

Claims

1. A method for determining an analyte concentration in a sample, comprising:

(a) applying the sample to a test sensor;

(b) applying an electrical or optical input signal to the sample;

(c) measuring at least one uncompensated output signal value i from the sample, wherein the value i is responsive to an undetermined concentration of the analyte in the sample;

(d) determining at least one slope deviation Δ

S value from a first complex index function f(CIndex) including at least a first term and a second term, wherein

the first term includes a product of a first weighing coefficient and at least a first error parameter; and

the second term includes a product of a second weighing coefficient and at least a second error parameter;

(e) determining a corrected analyte concentration A_corr in the sample from the at least one uncompensated output signal value by adjusting a previously determined reference slope S_cal with the at least one slope deviation Δ

S value and combining the adjusted slope with the at least one uncompensated output signal value,

wherein steps (d) and (e) are performed by a processor using computer readable software code.

2. The method of claim 1, where the at least one slope deviation Δ

S value is in a substantially linear relationship with a percent bias ((Δ

A/A_ref)*100%) of the determined analyte concentration,

wherein Δ

A represents the difference between the corrected analyte concentration A_corr and a reference analyte concentration A_ref.

3. The method of claim 1, wherein the previously determined reference slope S_cal is pre-determined with a reference instrument.

4. The method of claim 1, wherein the at least one slope deviation value Δ

S is represented as follows;

Δ

S=b₁*f(CIndex)+b₀,

wherein b₁ represents a slope and b₀ represents a constant.

5. The method of claim 1, wherein the first complex index function f(CIndex) further comprises at least one constant that is not equal to zero.

6. The method of claim 1, wherein one of the first term and the second term includes a raw analyte concentration value of the sample.

7. The method of claim 1, wherein one of the first term and the second term includes a temperature.

8. The method of claim 1, wherein one of the first term and the second term includes an error parameter responsive to a % Hct of the sample.

9. The method of claim 1, wherein each of the first error parameter and the second error parameter is independently selected from intermediate output signal values and values external to the at least one uncompensated output signal value i.

10. The method of claim 9, wherein the first error parameter and the second error parameter are responsive to error contributors causing an alteration of the at least one uncompensated output signal value.

11. The method of claim 9, wherein the first error parameter and the second error parameter are independently responsive to different error contributors and each of the first error parameter and the second error parameter has an R² correlation with Δ

S_cal of at least 0.3, wherein the Δ

S_cal is represented as follows;

12. The method of claim 1, wherein the at least one slope deviation Δ

S value determined from the first complex index function f(CIndex) has an R² correlation with Δ

S_cal of at least 0.6, wherein the Δ

S_cal is represented as follows;

13. The method of claim 2, wherein the determining the corrected analyte concentration A_corr in the sample further comprises determining corrected analyte concentrations of multiple samples and the first complex index function f(CIndex) provides the corrected analyte concentrations determined of the multiple samples with a standard deviation value of less than 5 for the combined percent biases of the multiple samples.

14. The method of claim 13, wherein the determined corrected analyte concentrations of the multiple samples fall within a ±

10% combined bias limit over the reference analyte concentrations.

15. The method of claim 13, wherein the determined corrected analyte concentrations of the multiple samples fall within a ±

8% combined bias limit over the reference analyte concentrations.

16. The method of claim 13, wherein the determined corrected analyte concentrations of the multiple samples fall within a +5% combined bias limit over the reference analyte concentrations.

17. The method of claim 1, further comprising:

a second complex index function, wherein different error parameters are transformed by the complex index function and the second complex index function to provide at least two slope deviation Δ

S values;

or

an index function, where different error parameters are transformed by the complex index function and the index function to provide at least two slope deviation Δ

S values.

18. The method of claim 1, further comprising normalizing the at least one slope deviation Δ

S value, wherein the normalizing is in response to a slope of a reference correlation equation or in response to a normalized slope function.

19. The method of claim 1, further comprising previously identifying at least one exclusion value and applying an exclusion test to the at least one exclusion value to identify a term to exclude from the first complex index function f(CIndex).