Methodological features of quantitative studies on medication adherence in older patients with chronic morbidity: A systematic review.

The growing number of chronic, multimorbid older adults encourages healthcare systems to cope with polypharmacy and non-adherence. However, methodology on how to provide effective interventions to enhance medication adherence is still object of debate. To describe methodological features of quantitative studies concerning older adults' medication adherence, by means of a PRISMA systematic review (Scopus, PubMed, Medline). A specific focus was devoted to theoretical models and to the ABC Taxonomy model, as stated by the EMERGE guidelines. 55 papers were included. Most of the studies were conducted using randomized control trials (63.6%) and focused on a single disease only (72.7%). Most of the interventions were provided by a single professional figure (70.9%). Medication adherence was mainly evaluated by means of questionnaires (61.8%) and by clinical records (30.9%). Sixteen studies considered a theoretical model in the intervention framework. The Initiation phase (ABC Taxonomy) was the most neglected. Future studies upon medication adherence should account real-life challenges such as multimorbidity, polypharmacy and interdisciplinarity, analyzing adherence as a complex, holistic process. Theoretical models may be useful to enhance the soundness of the results, to ease their comparability, to calibrate tailored strategies and to plan patient-centered interventions.