Medication non-adherence in chronic conditions

Abstract

Introduction: Medication adherence in chronic diseases is conceptualized as a multidimensional, longitudinal construct encompassing initiation, implementation, and discontinuation of therapy. Failure to initiate prescribed treatment constitutes primary medication non-adherence (PMN), whereas suboptimal implementation or premature discontinuation reflects secondary non-adherence. Refillbased measures primarily assess secondary non-adherence, whereas PMN remains insufficiently studied due to challenges in linking prescribing and dispensing data, despite its significant clinical and economic impact. Against this background, the present study aims to review the prevalence and determinants of primary and secondary non-adherence in chronic diseases and to elucidate their clinical implications. Material and methods: A narrative literature review was conducted using electronic databases including EBSCOhost and HINARI. Peer-reviewed articles published within the last five years were screened. Keywords used in the search strategy included: “medication adherence,” “persistence,” “discontinuation,” “chronic diseases”. Observational studies, systematic reviews, and clinical studies addressing determinants and outcomes of non-adherence in adult populations were included. Results: Primary non-adherence rates in chronic conditions are commonly reported between 14-20%, while persistence frequently declines below 50% within the first year of therapy. Non-adherence is consistently associated with increased emergency department utilization, higher morbidity, mortality, and avoidable healthcare expenditures. Across conditions, adverse drug reactions and the perception of medication-related harm represent prominent barriers affecting both initiation and continuation. Depression and psychological distress are repeatedly linked to reduced adherence across multiple chronic diseases. Multimorbidity, disease burden, regimen complexity, medication cost, and emergency care utilization further increase discontinuation risk. Facilitators of adherence are primarily relational and systemic, including trust in the healthcare team, continuity of care, sufficient consultation time, access to services, health education, social support, and perceived treatment benefit. A strong therapeutic alliance and effective communication help counteract negative beliefs and enhance long-term persistence. Conclusion: Non-adherence in chronic diseases is a multidimensional and phase-specific phenomenon influenced by clinical, psychological, and system-level determinants. Identifying the underlying barrier motivating non-adherence is more clinically meaningful than merely detecting its presence. Standardized methodological approaches and integrated health system strategies are essential to design targeted interventions aimed at improving initiation, implementation, and persistence in long-term pharmacotherapy.