Psychosocial Determinants of Medication Adherence: Global Structural Equation Modelling Analysis

Abstract Background: Medication non-adherence, where patients do not take medications as prescribed, is a major global concern, with global adherence rates for chronic conditions averaging only 50%–60%. This phenomenon led to poor treatment outcomes and increased healthcare costs. This study aimed to examine how psychosocial factors affect medication adherence using structural equation modelling (SEM), as understanding these factors is essential for developing appropriate interventions. Methods: A cross-sectional study was conducted using data collected from 4872 adults between 2021 and 2025 across 18 countries. Participants had at least one chronic condition requiring daily medication. Latent variables included medication beliefs, health literacy, illness perceptions, social support, healthcare relationships and medication complexity. SEM was used to examine the relationships between these variables and adherence, measured using the 8-item Morisky Medication Adherence Scale (MMAS-8). Results: Adherence rates varied by region, highest in Oceania (mean MMAS-8 = 6.8) and lowest in Africa (mean = 5.4). SEM showed that medication beliefs mediated the effects of health literacy and illness perceptions on adherence. Necessity beliefs were positively associated with adherence (β =0.43, P < 0.001), whereas concern beliefs (β = −0.38) and medication complexity (β = −0.19) were negatively associated. Healthcare relationships (β =0.24) and health literacy (β =0.15) had significant direct effects. Social support moderated the impact of complexity (β =0.21), buffering its negative effect. Patterns were consistent across regions, with some cultural variation. Conclusion: Medication beliefs are central to adherence and influenced by psychological factors. Tailoring interventions according to the cultural and regional aspects may improve the adherence outcomes.