Good adherence has been associated with improved blood pressure control (17) and reduced complications of hypertension (28,29). For example, in one study, health education interventions for urban-poor patients with hypertension were introduced sequentially in a randomized factorial design to a cohort of 400 ambulatory outpatients with hypertension over a 5-year period. The interventions resulted in an improvement in adherence, which was associated with better blood pressure control and a significant reduction (53.2% less) in hypertension-related mortality rates (28).

In another study, patients who did not adhere to beta-blocker therapy were found to be 4.5 times more likely to have complications of coronary heart disease than those who did (23). However, whether this increased complication rate was directly related to poor adherence to antihypertensive medication is not certain.