Medication adherence among geriatric outpatients prescribed multiple medications

Poor medication adherence (PMA) is associated with higher risks of morbidity, hospitalization, and mortality. Polypharmacy is not only a determinant of PMA but is also associated with many adverse health outcomes.

We aimed to determine the prevalence and correlates of PMA in an older population with polypharmacy.

Baseline data from 193 older adults from the Medication Safety Review Clinic Taiwan Study were analyzed. Patients were either prescribed ≥8 long-term medications or visited ≥3 different physicians between August and October 2007. PMA was defined as taking either <80% or >120% of prescribed amounts of a medication. Patients were classified as no (0%), low level (>0 but <25%), and high level (≥25%) PMA depending on what percentage of entire medication regimen taken reached PMA.

Mean (SD) age was 76 (6) years, and mean number of medications was 9 (3), with a mean medication class number of 4 (1). Of the 1713 medications reviewed, 19% had PMA. However, at patient level, 34%, 32%, and 34% of patients were classified as no, low level, and high level PMA, respectively. Correlates varied by levels of PMA. Compared with patients without PMA, higher medication class number and use of alimentary tract, psychotropic, and hematologic agents were associated with both low and high level PMA. History of dizziness was associated with low level PMA, and higher Mini Mental Status Examination score was associated with high level PMA.

To enhance medication adherence in older adults prescribed multiple medications, medication class numbers and certain high-risk medication classes should be taken into account. Physicians should also routinely assess systemic (eg, cognition) or drug-specific characteristics (eg, side effects).