Medication adherence and treatment-resistant hypertension: a review.

Nonadherence is a common reason for treatment failure and treatment resistance. No matter how it is defined, it is a major issue in the management of chronic illnesses. There are numerous methods to assess adherence, each with its own strengths and weaknesses; however, no single method is considered the best. Nonadherence is common in patients with hypertension, and it is present in a large proportion of patients with uncontrolled blood pressure taking three or more antihypertensive agents. Availability of procedure-based treatment options for these patients has shed further light on this important issue with development of new methods to assess adherence. There is, however, no consensus on the management of nonadherence, which reflects the complex interplay of factors responsible for it.