Systematic Review of Outcomes for Assessment of Medication Adherence Enhancing Interventions: An ISPOR Special Interest Group Report

Objectives: The lack of universal guidance on outcome measures for evaluating medication adherence enhancing interventions (MAEIs) poses a challenge for assessing their effectiveness. This literature review aimed to provide a systematic overview of outcome measures currently used for the value assessment of MAEIs. Methods: We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and searched MEDLINE, PsycINFO, Scopus, CINAHL, and Academic Search Complete for randomized and nonrandomized clinical trials, prospective cohort studies, model-based economic evaluations, and value frameworks published in English between January 2010 and September 2020. Two independent reviewers screened all titles and abstracts, followed by a full-text review. Due to the large number of relevant studies, data extraction was limited to articles published between January 2018 and September 2020. We collected data on the general characteristics of the study, the type of intervention, and the outcomes measured. Results: We screened 14 685 records and identified 308 articles for data extraction. Behavioral interventions were the most common (n = 143), followed by educational interventions (n = 110) and mixed-method interventions (n = 73). Outcomes were clustered into 7 categories with medication adherence (n = 286) being the most frequently measured, followed by clinical outcomes (n = 155), health-related quality of life (n = 57), resource use (n = 43), patient satisfaction (n = 31), economic outcomes (n = 18), and other outcomes (n = 76). Conclusions: Various outcomes measures have been used to evaluate MAEIs, with only a small number of studies exploring economic and patient-reported outcomes. Future research is warranted to develop a consensus-based set of criteria for assessing MAEIs to facilitate the comparison of interventions and enable informed decision making.