Identifying core strategies and mechanisms for spreading a national medicines optimisation programme across England-a mixed-method study applying qualitative thematic analysis and Qualitative Comparative Analysis.

By qualitatively comparing experiences of spreading one innovation across different contexts, we identified common strategies, causal mechanisms, and contextual determinants. The QCA identified one core combination of two strategies/mechanisms. The identification of core strategies/mechanisms and common pre-conditional and mediating contextual determinants of a specific innovation offers spread facilitators and implementers a priority list for tailoring spread activities.