What is Medication Adherence?

Medication adherence, or taking medications correctly, is defined as the extent to which patients take medication as prescribed by their doctors. This involves factors such as getting prescriptions filled, remembering to take medication on time, and understanding the directions. Medication adherence can be influenced by many factors. It also assumes the patient has the knowledge, motivation, skills and resources to follow the health care providers prescription. Nonadherence can include delaying or not filling a prescription, skipping doses, splitting pills, or stopping a medication early. Not only does nonadherence increase costs, but it also leads to poorer health outcomes for patients.

Read more about the impacts of nonadherence here.

“Keep watch also on the fault of patients which makes them lie about taking of things prescribed.”

— Hippocrates, circa 500 B.C.

How is Adherence Measured?

There are a number of ways to measure medication adherence in patients of varying degrees of effectiveness. The most direct method is to measure the metabolites of the drug in the patient, but while accurate it is costly and invasive. A variety of calculations have been introduced to calculate adherence based on pharmacy claims data, though no single approach has been uniformly accepted. Pill counts and pharmacy databases are simple and inexpensive, but don’t prove the medication was taken by the patient. Self-reported measurements tend to overestimate adherence and fail to meet objective standards. Generally, more than one method of measurement would be used to determine a patient’s adherence.