Assessing agreement between two methods of measuring blood glucose level without Bland-Altman limits

Abstract

Objective: To describe a new method of assessing agreement between two methods of measuring blood glucose level in view of several problems with the currently used Bland-Altman method.

Methods: Study the deficiencies in the Bland-Altman method and propose a simple method that overcomes these deficiencies. The simple method does not require the calculation of Bland-Altman limits.

Results: Clinical tolerance limits, which are needed anyway, can be directly used to obtain the agreement by the percentage of differences within these limits. This method is simple, robust, and nonparametric. It is more flexible also as the clinical tolerance limits can be varied for different values of the measurement such as to have close agreement at critical values and relaxed agreement at other values. Non-symmetric limits can also be set up under the simple method.

Conclusion: The method of assessing agreement between two methods of measuring blood glucose level can be greatly improved by directly using clinical tolerance limits without calculating the Bland-Altman limits.

Keywords: Agreement assessment; Bland-Altman method; Blood glucose measurement; Clinical tolerance limits; Nonparametric method.