Multilevel Ecological and COM-B Determinants of Medication Adherence in Adults With Diabetes

This study is a cross-sectional, observational investigation designed to examine multilevel determinants of medication adherence among adults with diabetes using an integrated Health Ecology and Capability-Opportunity-Motivation-Behavior (COM-B) theoretical framework. The study is grounded in the premise that medication adherence is a complex health behavior shaped by interacting contextual and behavioral mechanisms rather than solely by individual patient choice.

From an ecological perspective, medication-taking behavior occurs within nested environments that include intrapersonal characteristics, interpersonal relationships, healthcare interactions, and broader structural or access-related conditions. Individual-level influences include cognitive and perceptual factors that shape how patients understand and interpret medication-related information. Interpersonal influences include family involvement and social support structures that may facilitate or hinder routine medicine-taking. Healthcare interaction-level determinants reflect the quality of communication between patients and healthcare providers, including clarity of explanations and comprehensibility of prescriptions. Structural and access-related determinants encompass practical constraints such as medication availability, affordability, geographic access to care, and regimen complexity.

While ecological models provide contextual organization of determinants, they do not fully explain how these determinants translate into observable behavior. Therefore, this study incorporates the COM-B framework to provide a mechanistic explanation. According to COM-B, behavior occurs when three essential components are present: psychological and physical capability, social and physical opportunity, and reflective and automatic motivation. Within the integrated framework used in this study, ecological determinants are mapped onto COM-B domains to examine how contextual influences operate through behavioral mechanisms to shape medication adherence.

Data will be collected during a single outpatient encounter using structured, validated self-report instruments and prescription audit methods. Medication adherence will be assessed using a standardized adherence scale. Measures representing ecological determinants will capture literacy-related capability, beliefs and perceptions influencing motivation, interpersonal and social support influencing social opportunity, communication quality influencing capability and opportunity, and structural or access-related constraints influencing physical opportunity. No intervention will be delivered, and no follow-up assessments will occur.

The analytical strategy is theory-guided. Descriptive statistics will summarize adherence levels and determinant distributions. Bivariate analyses will explore associations between adherence and individual predictors. Hierarchical multivariable regression models will be constructed sequentially according to COM-B domains to quantify their relative contribution to explained variance in adherence behavior. Mediation analyses will examine whether capability, opportunity, and motivation domains statistically account for the relationship between ecological determinants and adherence outcomes.

The study is designed to generate empirically grounded, theory-informed evidence clarifying which contextual layers and behavioral mechanisms are most strongly associated with medication adherence in diabetes care. By integrating ecological breadth with behavioral specificity, the findings are expected to support development of future pharmacist-led and health system-level strategies targeting modifiable determinants of adherence in resource-constrained settings.

Inclusion criteria

• Adults aged 18 years or older
• Diagnosed with at least one chronic disease (e.g., diabetes mellitus, hypertension, cardiovascular disease, chronic respiratory disease, chronic kidney disease) for a minimum duration of six months
• Prescribed long-term medication therapy
• Able to understand and respond to the study questionnaire
• Willing to provide written informed consent

Exclusion criteria

• Patients with acute medical conditions requiring immediate care
• Individuals with severe cognitive impairment or psychiatric illness that would preclude reliable participation
• Patients who are terminally ill
• Patients unwilling to participate or provide consent