Oſten, compliance is also used and the two can be used interchangeably in research and clinical practice . It describes “the extent to which the patients’ behavior (including medication-taking) coincides with medical or healthcare advice”, yet its meaning has become more negative regarding patient’s behaviors, since it implies patient’s passivity.
Nevertheless,measurement of medication adherence can be quite challenging since and parameters of acceptable adherence need to be carefully delineated and appropriated for individual situations. There are numerous tools available for these measurements, but these need to prove to be valid, reliable, and sensitive to change. The selection of a method to monitor adherence should be based on individual attributes and goals/resources of the study or the clinical setting. Currently none of the available methods can be considered as a gold standard and the combination of methods is recommended.
Objective measures include pill counts, electronic monitoring, secondary database analysis and biochemical measures and are thought to represent an improvement over subjective measures. As such, objective measures should be used to validate and correlate the subjective ones. However, a meta-analysis on adherence outcomes states that a multi-subjective-measure approach may have higher sensitivity, but not accuracy, over employing a single objective measure. In summary, subjective and objective measures have both advantages and disadvantages and should be used in combination.
The Medication Events Monitoring System (MEMS) is the most commonly used EMP device in medication adherence studies.