Compliance descriptors: analysis and evaluation in terms of therapeutic effect.

The aim of this work was to evaluate the performance of various compliance parameters in order to identify those which best assess the impact of compliance on therapeutic issues. We will discuss the particularities and restrictions of these parameters by considering two criteria, namely sensitivity index and reliability, which respectively describe strength and robustness of the relationship between these parameters and compliance. Using real and virtual data, performance analysis of compliance parameters was carried out for drugs whose pharmacokinetic properties govern the time course of their actions. Within this context, it was found that the percentage of taken doses (PTD), the most widely used parameter, poorly performed in the evaluation of the therapeutic impact of compliance. On the other hand, the adjusted percentage of correct doses (PCD*) which we propose here, showed the best reliability, making it the most appropriate parameter for the comparison of different compliance patterns. The percentage of correct doses (PCD) has, in its turn, the highest sensitivity index and thus should be preferred for the assessment of changes in compliance. Hence, a perfect parameter for the evaluation of compliance impact cannot be universally identified since each parameter can have its own characteristic advantages and limitations. The methodology proposed here is general enough to be adapted for similar drug classes to evaluate their compliance descriptors.