High Medication Non-Adherence Rates and its Drivers in the General Population: A Cross-sectional Study Using the OMAS-37 Adherence Survey Tool.

Substantial variability in patients' medication adherence underscores the key significance of pharmacists and other healthcare providers proactively aiding individuals in achieving optimal medication outcomes. Medication-taking behaviours, barriers, and beliefs varies significantly among medication users. It is crucial to ascertain these factors when designing adherence interventions. The OsloMet Adherence-to-medication Survey tool (OMAS-37) is designed to quantify the degree of adherence, and to assess 37 unique causes for non-adherence. The aim of this study was to assess non-adherence among medication users in the general population utilising the OMAS-37 tool. A cross sectional study among medication users in Norway was conducted in 2021. The features of the general population and three patient subgroups-cardiovascular, pain, and mental health disorders-were characterized and compared using Kruskal-Wallis tests. Of the 812 participants, with a median age of 50 (IQR 37-59) and 91% (n = 736) identifying as female, 64% (n = 517) exhibited high non-adherence scores indicating poor medication. Main reasons included forgetfulness (42%, n = 343), perceived improvement in health (40%, n = 326), and fear of adverse drug reactions (39%, n = 320). Statistically significant positive adherence factors encompassed increasing age, higher education, medication decision involvement, and pill organiser usage. The cardiovascular subgroup exhibited significantly better adherence than the pain and mental health disorders subgroups. The total sample and all three subgroups demonstrated some variation in the main causes for non-adherence. This first study employing OMAS-37 reveals high non-adherence levels and varying causes of non-adherence among different patient groups, emphasizing the need for targeted adherence interventions.