Medication adherence in this study is theoretically defined
as the extent or degree to which a person’s medicationtaking
behavior corresponds with agreed recommendations
from a healthcare provider.6 This definition
aligns with the implementation phase of medication adherence
as described by Vrijens and colleagues,27 where
actual dosing should correspond to the prescribed dosing
from initiation of therapy until the last dose is taken.
There are many methods for measuring adherence,
but no consensus or gold standard has been identified In fact, there are advantages and disadvantages to all
methods. For instance,with serum drug levels, individual
metabolism and drug-drug or drug-food interactions can
affect the data. Electronic monitoring caps are expensive
andmonitor onlywhen a medication cap is removed, not
when the medication is taken. Self-report may be influenced
by problems with recall, cognitive function, or
the desire of participants to give socially acceptable responses.
However, self-report has been shown to correlate
with pill count28 and electronic medication caps.29 Therefore,
a self-report measure was used in this study