Children Learning About Second-hand Smoke (CLASS II) : a mixed methods process evaluation of a school-based intervention

Background: Children are vulnerable to the effects of second-hand smoke exposure. Creating smoke-free homes is an effective strategy to limit exposure. We developed a smoke-free intervention (SFI) using children as a catalyst for change and teaching skills to negotiate a smoke-free home. In this paper, we present the process evaluation conducted within a pilot trial. Methods: This was a mixed-methods study comprising qualitative interviews and quantitative fidelity assessment of SFI delivery. Interviews in the six intervention schools were conducted with six headteachers and 12 teachers. These explored experiences of delivering the SFI, perceived impact, barriers and facilitators to success, and ideas for improvement and for scaling up. The data were analysed using framework analysis. Delivery of the SFI was observed and fidelity scores calculated. Results: The SFI was acceptable to headteachers and teachers. Fidelity scores ranged from 27/40 to 37/40. Didactic components were more fully implemented than interactive components. Time to complete the sessions, timing in the school day and school calendar were key challenges. Embedding the SFI into the curriculum was a potential solution. Conclusions: These findings provide useful information to finalise the content and delivery and inform the scale-up of the SFI for our definitive trial, which is now underway. Trial registration: ISRCTN68690577