Abstract
BACKGROUND: Implementation depends on healthcare professionals being able to make sense of a new intervention in relation to their routine practice. Normalisation Process Theory refers to this as coherence work. However, specifying what it takes to achieve coherence is challenging because of variations in new interventions, routine practices and the relationship between them. Frameworks for intervention description may offer a way forward, as they provide broad descriptive categories for comparing complex interventions. To date such frameworks have not been informed by implementation theory, so do not account for the coherence work involved in holding aspects of routine practice constant while doing other aspects differently. Using speech and language therapy as an empirical exemplar, we explored therapists' experiences of practice change and developed a framework to show how coherence of child speech interventions is achieved. METHODS: We conducted a retrospective case-based qualitative study of how interventions for child speech problems had changed across three NHS speech and language therapy services and private practice in Scotland. A coherence framework was derived through interplay between empirical work with 42 therapists (using in-depth interviews, or self-organised pairs or small focus groups) and Normalisation Process Theory's construct of coherence. FINDINGS: Therapists reported a range of practice changes, which had demanded different types of coherence work. Non-traditional interventions had featured for many years in the profession's research literature but not in clinical practice. Achieving coherence with these interventions was intellectually demanding because they challenged the traditional linguistic assumptions underpinning routine practice. Implementation was also logistically demanding, and therapists felt they had little agency to vary what was locally conventional for their service. In addition, achieving coherence took considerable relational work. Non-traditional interventions were often difficult to explain to children and parents, involved culturally uncomfortable repetitive drills and required therapists to do more tailoring of intervention for individual children. CONCLUSIONS: The intervention coherence framework has practical and theoretical applications. It is designed to help therapists, services and researchers anticipate and address barriers to achieving coherence when implementing non-routine interventions. It also represents a worked example of using theory to make intervention description both user-focused and implementation-friendly.