Medication Adherence Across Diseases Using the 8-Item Morisky Medication Adherence Scale (MMAS-8): A Systematic...

Medication adherence is a key determinant of clinical outcomes in patients with noncommunicable chronic diseases, where long-term pharmacotherapy, continuous follow-up, and patient engagement are often required. This systematic review evaluated the use of the 8-item Morisky Medication Adherence Scale (MMAS-8) to assess medication adherence in adults with noncommunicable chronic diseases and summarized the adherence levels, associated factors, and methodological characteristics reported across clinical settings. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement. Searches were performed in PubMed, ScienceDirect, and Google Scholar for studies published between January 2020 and September 2025. Eligible studies included primary research articles in English or Spanish that used the MMAS-8 as the main tool for assessing medication adherence in adults. A total of 989 records were identified. After removal of 71 duplicates, 918 records were screened by title and abstract, and 27 full-text articles were assessed for eligibility. Finally, 19 studies met the inclusion criteria and were included in the qualitative synthesis. The included studies evaluated conditions such as hypertension, diabetes mellitus, cardiovascular disease, breast cancer, psoriasis, hypothyroidism, depression, multiple sclerosis, chronic pain, and multimorbidity. Overall, low or medium adherence was frequently reported, although adherence levels varied according to disease, care setting, population characteristics, and method of scale administration. Factors associated with adherence included sociodemographic characteristics, family support, health literacy, adverse effects, treatment satisfaction, quality of life, and pharmacist-led interventions. The MMAS-8 appears to be a practical tool for identifying potential medication adherence problems in chronic disease populations; however, its self-reported nature, methodological heterogeneity, and variability in administration limit direct comparability across studies. Future research should standardize the MMAS-8 application and combine it with objective adherence measures.