Assessing similarity in bioanalytical methods

Due to the comparative nature of a bioassay, the relative potency is usually used to describe the potency of a sample. Only when the two samples are similar can a valid and meaningful estimate of relative potency be obtained. Thus, assessing similarity is a crucial part in developing a bioanalytical method. The current commonly used approach for assessing similarity focuses on the response parameters, such as the slope in the linear case, using either a significance test or an equivalence test. The current direct evaluation of the response parameters ignores the information about the shape of the curve and the possible variance heterogeneity. To overcome this, we propose a method based on the idea of equivalence testing that compares the shapes of the curves directly. The new method first measures the difference of the response between the standard sample and the test sample at each of the concentration (dilution) levels and then determines whether the differences are consistent by comparing them to the equivalence limits. The benefits of the new method are investigated by a simulation study. LAY ABSTRACT: Due to the comparative nature of a bioassay, the relative potency is usually used to describe the potency of a sample. Only when the two samples are similar can a valid and meaningful estimate of relative potency be obtained. Thus, assessing similarity is a crucial part in developing a bioanalytical method. The current commonly used approach for assessing similarity focuses on the response parameters, such as the slope in the linear case, which have many drawbacks To overcome this, we propose a method based on the idea of equivalence test but comparing the shape of curve directly. The new method first measures the difference of the response between the standard sample and the test sample at each of the concentration (dilution) levels and then determines whether the differences are consistent by comparing them to the equivalence limit.