Achieving Intervention Coherence in Routine Practice: A Qualitative Case-Based Study from an Implementer Perspective

Background Implementation depends on healthcare professionals making sense of a new intervention in relation to their routine practice, a process Normalisation Process Theory refers to as coherence. However, specifying what it takes to achieve coherence is challenging because of variation in new interventions, routine practice, and the relationship between them. Frameworks for intervention description offer a way forward in specifying coherence, 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 speech and language therapists anticipate and address barriers to coherence in their context when implementing non-routine interventions. It is also a worked example of using theory to make intervention description user-focused and implementation-friendly.Contributions to the literature · Intervention descriptions identify what healthcare professionals need to do to implement new interventions but not how this is the same or different from their routine practice. We applied qualitative research and implementation theory to this problem of specifying ‘coherence’. · We focused on speech and language therapists because their work and the interventions they use are very complex. By understanding changes in their routine practice, we identified key elements for achieving coherence. · Our worked example of generating a coherence framework may be applicable in other professional areas where it is challenging to describe and implement complex behavioural interventions.