Patients who are prescribed medicines take only about half of their doses and many stop treatment entirely. Assisting patients to adhere better to medicines could improve their health, and many studies have tested ways to achieve this.
We updated our review from 2007 to answer the question: What are the findings of high-quality studies that tested ways to assist patients with adhering to their medicines?
We retrieved studies published until 11 January 2013. To find relevant studies we searched six online databases and references in other reviews, and we contacted authors of relevant studies and reviews.
We selected studies reporting a randomized controlled trial (RCT) comparing a group receiving an intervention to improve medicine adherence with a group not receiving the intervention. We included trials if they measured both medicine adherence and a clinical outcome (e.g. blood pressure), with at least 80% of patients studied until the end.
The studies differed widely regarding included patients, treatments, adherence intervention types, medicine adherence measurement, and clinical outcomes. Therefore, we could not combine the results in statistical analysis to reach general conclusions, as it would be misleading to suggest that they are comparable. Instead, we provide the key features and findings of each study in tables, and we describe intervention effects in studies of the highest quality. The present update included 109 new studies, bringing the total number to 182. In the 17 studies of the highest quality, interventions were generally complex with several different ways to try to improve medicine adherence. These frequently included enhanced support from family, peers, or allied health professionals such as pharmacists, who often delivered education, counseling, or daily treatment support. Only five of these RCTs improved both medicine adherence and clinical outcomes, and no common characteristics for their success could be identified. Overall, even the most effective interventions did not lead to large improvements.
Characteristics and effects of interventions to improve medicine adherence varied among studies. It is uncertain how medicine adherence can consistently be improved so that the full health benefits of medicines can be realized. We need more advanced methods for researching ways to improve medicine adherence, including better interventions, better ways of measuring adherence, and studies that include sufficient patients to draw conclusions on clinically important effects.