Facilitators, barriers and intervention strategies for medication adherence in patients receiving thyroid hormone...

Thyroid hormone replacement therapy (THRT) is the lifelong treatment for hypothyroidism, yet persistent non-resolution of the condition necessitates indefinite adherence and systematic evidence on facilitators, barriers, and targeted interventions to optimize medication adherence in THRT remains limited.

This mixed-methods systematic review aimed to: 1) identify influential barriers and facilitators of THRT adherence using the Capability, Opportunity, Motivation-Behavior (COM-B) model and Theoretical Domains Framework (TDF); and 2) map potential and effective behavior change techniques (BCTs) to the TDF domains corresponding to the identified barriers.

Ten databases were searched from inception to November 2024 and then updated in November 2025. Study quality was assessed using the Mixed Methods Appraisal Tool (MMAT). For purpose 1: the COM-B model and TDF, were used to code barriers and facilitators extracted from primary studies to one or more of the 14 domains of TDF, then identify the key barriers and ranked the top five influential TDF domains using three criteria. For purpose 2: the potential BCTs were recommended to target key barriers identified in TDF domains.

The 44 studies were included and mapped to 14 domains of TDF. Top five influential TDF to medication adherence were environmental context and resources (e.g., inconvenient administration times), social influences (e.g., family support), knowledge (e.g., lack of disease/medication knowledge), belief about consequences (e.g., concerns about side effects), and social/professional role and identity (e.g., older age as a facilitator). Twenty-seven potentially effective BCTs were identified from the included studies and the most frequently used BCTs to target five key TDF domains were social support from their partners, multilevel care intervention and effective physician communication.

This review highlights multifaceted barriers of medication adherence in patients receiving THRT and proposes theory-informed strategies to address them. Future research should validate these strategies in real-world settings and explore contextual adaptations for diverse populations.