Examination of the Link Between Medication Adherence and Use of Mail-Order Pharmacies in Chronic Disease States

BACKGROUND: Higher medication adherence is associated with positive health outcomes, including reduction in hospitalizations and costs, and many interventions have been implemented to increase patient adherence. OBJECTIVES: To determine whether patients experience higher medication adherence by using mail-order or retail pharmacies. METHODS: Articles pertaining to retail and mail-order pharmacies and medication adherence were collected from 3 literature databases: MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and International Pharmaceutical Abstracts (IPA). Searches were created for each database and articles were compiled. Articles were screened for exclusion factors, and final articles (n=15) comparing medication adherence in patients utilizing mail and retail pharmacies were analyzed. For each study, various factors were identified including days supply, patients’ out-of-pocket costs, prior adherence behavior, therapeutic class, measure of adherence, limitations, and results. Studies were then categorized by disease state, and relevant information from each study was compared and contrasted. RESULTS: The majority of studies—14 out of the 15 reviewed—supported higher adherence through the mail-order dispensing channel rather than through retail pharmacies. There are a number of reasons for the differences in adherence between the channels. Study patients who used mail-order pharmacies were more likely to have substantially higher prior adherence behavior, socioeconomic status, and days supply of medicines received and were likely to be offered financial incentives to use mail-order. The few studies that attempted to statistically control for these factors also found that patients using mail-order services were more adherent but the size of the differences was smaller. The extent to which these results indicate an inherent adherence advantage of mail-order pharmacy (as distinct from adherence benefits due to greater days supply, lower copays, or more adherent patients selecting mail-order pharmacies) depends on how well the statistical controls adjusted for the substantial differences between the mail and retail samples. CONCLUSIONS: While the research strongly indicates that consumers who use mail-order pharmacies are more likely to be adherent, more research is needed before it can be conclusively determined that use of mail-order pharmacies causes higher adherence.