The Access, Initiation, Engagement, Retention, and Recovery (AIERR) Model: A Stage-Based Framework for Understanding Mental Health Service Utilization

Background/Objectives: Mental health service utilization gaps remain a persistent global public health challenge. Dropout rates from outpatient treatment range from 19.7% to 30.8%, and only 30–60% of individuals with lifetime mental illness are in active recovery at any given time. Existing theoretical frameworks—including Andersen's Behavioral Model, the Health Belief Model, and the COM-B framework—each address isolated phases of the care continuum but offer no unified structure for understanding the complete, sequential journey from first contact through sustained recovery. This article introduces the Access, Initiation, Engagement, Retention, and Recovery (AIERR) model to address this theoretical gap. Methods: A conceptual review was conducted following Hulland's (2020) framework for theory development through narrative synthesis. Literature was identified through targeted searches in PubMed, PsycINFO, and Google Scholar, prioritizing peer-reviewed empirical studies, systematic reviews, and foundational theoretical frameworks. Sources were assigned to AIERR stages using predefined decision rules corresponding to each phase's defining characteristics. Results: AIERR maps five sequential, interconnected stages: Access (structural, cultural, and systemic conditions enabling service reach), Initiation (the transition from provider identification to first appointment attendance), Engagement (active and meaningful treatment participation), Retention (sustained continuity of care), and Recovery (long-term reclamation of life quality and community belonging). For each stage, the framework identifies individual-level and structural-level barriers, facilitating conditions, and targeted intervention points. Three features distinguish the model: client-centeredness, explicit bidirectional individual–structural analysis, and stage-specific intervention mapping. Conclusions: AIERR advances mental health services theory by providing an integrative structure that unifies previously siloed frameworks, establishes stage-specificity as a core theoretical principle, and reorients research and intervention strategy toward the upstream structural conditions that produce downstream utilization failures. The model equips researchers with a unified conceptual vocabulary, offers practitioners a stage-specific roadmap for intervention planning, and enables health systems to identify where specific populations are disproportionately losing contact with care. Implications for health equity research, clinical practice, and health systems design are discussed.