Medication Adherence: A Literature Review

Charlotte A. Kenreigh, PharmD, and Linda Timm Wagner, PharmD


October 12, 2005

In This Article

Hypertensive Patients

Grant and colleagues[10] examined pharmacy claims data for antihypertensive agents in a single state health insurance plan over a 4-year period. The primary goal of the study was to examine the cumulative medication adherence (CMA), defined as the percentage of days the patient had medication available. CMA was calculated by determining the total number of days of medication dispenseddivided by the total number of days between the first and last prescriptions.

The mean CMA was 82.8% for all patients. Of interest, patients who had a greater CMA with the initial antihypertensive regimen were more likely to need an increase in the antihypertensive regimen than patients with a lower CMA to their initial regimen. This was true after controlling for age, number of prescribing physicians, and type of medication used initially.[10]

The implications of these findings are important, because healthcare providers often assume that a poor clinical response to an initial antihypertensive regimen may be due to nonadherence to the therapy. By contrast, this study indicates that more often than not, a poor initial response is more likely to be related to insufficient potency.


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