Clinical trials have demonstrated that the treatment of mild-to-moderate hypertension can reduce the
risk of stroke by 30 to 43% (1–4) and of myocardial infarction by 15% (5). Other costly consequences of
untreated hypertension can also be prevented or minimized by effective treatment. Examples of the
benefits of treatment include reduction in risk of cardiac failure, reduction in incidence of dementia (6),
preservation of renal function and prevention of blindness in diabetic patients with hypertension (7–9).
Traditionally, the term compliance has been employed to mean the extent to which the patient, when
taking a drug, complies with the clinician’s advice and follows the regimen (10). However, the new era of
patient-oriented care has led to the use of this term being questioned, and alternative terms such as
adherence, persistence and concordance have been suggested (11–14).
In addition to the confusing terminology in the area of adherence, there has been controversy over the
use of 80% as a cut-off point to distinguish adherence from nonadherence. In most studies, nonadherence
has been considered to occur when patients do not take ≥ 80% of their prescribed antihypertensive
drugs (15,16).
Whatever the definition, poor adherence to treatment is the most important cause of uncontrolled
blood pressure (13,14,17) and only 20 to 80% of patients receiving treatment for hypertension in reallife
situations are considered to be “good compliers” (18).