Medication Adherence: A Literature Review

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


October 12, 2005

In This Article


Medication adherence is defined by the World Health Organization as "the degree to which the person's behavior corresponds with the agreed recommendations from a health care provider."[1] Poor adherence to prescribed regimens can result in serious health consequences. For instance, a recent study found that the risk of hospitalization was more than double in patients with diabetes mellitus, hypercholesterolemia, hypertension, or congestive heart failure who were nonadherent to prescribed therapies compared with the general population.[2]

Rates of nonadherence vary widely in the literature and can be very high, even in the tightly controlled environment of a clinical trial. Multiple factors contribute to nonadherence. For instance, patients with chronic conditions are less likely to follow prescription orders than those with acute conditions.[3]

A patient's ability and willingness to follow a prescribed regimen directly influences the effectiveness of that therapy. One factor is the patient's ability to read and understand medication instructions. Patients with low literacy may have difficulty understanding instructions; this ultimately results in decreased adherence and poor medication management.[4]Issues of low literacy must be recognized and strategies designed with this limitation in mind.[4]

Current practices, such as the increased use of mail service pharmacies and reduced time available for the pharmacist to provide patient counseling, present challenges for pharmacists to effectively assess and detect medication adherence issues. However, pharmacists have a unique role in the medication management system that places them in a position to positively affect medication adherence. This requires the continued review of new information so that new concepts and ideas can be incorporated into patient counseling and intervention programs. This paper reviews some of the new trials reported in 2005 on medication adherence, with particular emphasis on how pharmacists might incorporate this knowledge into their practices.


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