Background: A common problem among patients with chronic diseases is poor adherence with prescribed medication. Studies have shown that certain interventions can improve adherence and clinical outcomes.
Method: We selectively searched the PubMed database for publications on the treatment of hypertension that contained the terms "adherence," "drug," "treatment, "outcome," "hypertension," and "randomized controlled trial."
Results: The interventions studied were highly varied, ranging from the use of calendar blister packs to complex patient education programs. 62% of the studies that we identified documented an improvement in adherence after an intervention (median Cohen's d = 0.52). In 92% of cases, improved adherence was associated with a significant improvement in clinical end points (median Cohen's d = 0.34).
Conclusion: The promotion of adherence to prescribed medication is clearly desirable. Studies on the treatment of hypertension have shown that attempts to improve adherence often fail. In most studies, however, improved adherence led to better clinical outcomes. Simplification of drug regimens (e.g., reducing the number of pills taken per day) is the single most effective way to promote adherence. Moreover, the findings of studies on the treatment of hypertension and other diseases suggest that shared decision-making should be the basis of physicianpatient discussions about medication. Suitable medications can also be chosen in order to maximize safety and efficacy even if adherence is incomplete. It would also be desirable for studies on the promotion of adherence to be carried out in Germany, under the specific conditions that prevail in our national health-care system.