Inside the black box: Refining intervention theory in the PriDem dementia care study

IntroductionThe PriDem programme developed a flexible, primary care-led intervention to improve post-diagnostic dementia support, involving Clinical Dementia Leads (CDLs) working with general practices to strengthen care systems. Programme theory was articulated in a logic model, to guide a feasibility implementation study, which demonstrated intervention feasibility, acceptability, and potential for systems-level change. The process of refining programme theory following feasibility testing can appear as a black box; rarely reported in detail. This paper presents a structured exemplar of theory refinement, addressing this recognised gap in implementation science. MethodsA deductive thematic analysis was conducted, using the logic model as a framework. We synthesised previously reported findings with new qualitative insights from feasibility interviews, fieldnotes, supervision records and researcher reflections. Confirmed, refined, and newly emergent theoretical components were identified and the logic model updated. ResultsMany original theory elements were confirmed, including improved review processes leading to enhanced care plan personalisation and staff training increasing confidence in care delivery. New mechanisms were identified, such as mapping local services as a relational tool and care planning templates as educational resources. Pre-implementation activities, such as specific CDL training and champion identification, emerged as critical to success. Role ambiguity and capacity concerns acted as negative mechanisms, impeding implementation. These insights informed a revised logic model to guide future scale-up. ConclusionsThis paper demonstrates the value of theory refinement following feasibility testing. By unpacking the black box of implementation, we offer a transparent model for optimising complex interventions in primary care-led dementia support. Trial registration numberISRCTN11677384