Full adherence to medication is required as the drug can be effective only when it is taken. Nonetheless, maintaining strict medication adherence is required that deems maintaining administration timing, dosage quantity, and frequency. A wealth of reports revealed that up to 50% of the patients either never fill their medication prescriptions or do not use the medication as prescribed to them in medication regimens. Unfortunately, poor adherence is prevalent among populations with chronic illnesses, which leads to hospital admission.
A number of approaches have been used for the aim of
monitoring medication adherence because it has been shown that improving
adherence to medical therapy would substantially lead to both health and
economic benefits.
In general, two key factors should be considered when
discussing medication adherence. The
first factor is monitoring, which is alternatively referred to as assessment,
quantification, measurement, or
evaluation. Medication monitoring means using some methods for observing and
also whether the patient has taken the medication or not. Hence, the
effectiveness of the monitoring method plays a central role.
The second factor is intervention. Interventions refer
to the means that can be used for improving adherence to medication or
correcting it once erroneous or drift is detected. However, the latter is more in the domain of
the psychological and social sciences as it requires understanding the
cultural, psychological, and social factors that affect the patient’s behavior,
and thus it is out of the scope of this paper.
Methods that have been utilized for measuring
medication adherence so far can be broadly divided into two categories, direct
and indirect. Direct methods of measurement of adherence include direct
observation of the patient while taking the medication, laboratory detection of
the drug in the biologic fluid of the patient (i.e., blood or urine),
laboratory detection of the presence of non-toxic markers added to the
medication in the biologic fluid of the patient, and laboratory detection of
the presence of biomarkers in the dried blood spots.
Meanwhile, the patient’s self-reporting,
pill-counting, assessing pharmacy refill rates, and using electronic medication
event tracking systems are examples of indirect methods of measuring adherence.
There is no gold standard measurement system that fulfills the criteria for optimal
medication adherence monitoring. Each category comes with benefits and
limitations at the same time.
Direct measures are accurate, but they may require
invasiveness, and they are usually expensive. In comparison, indirect methods
are less expensive and provide a good estimation of medication adherence.
However, these methods rely on the reliability of the user. As such, these
factors should be taken into consideration when selecting the adherence
measurement methodology.