Abstract Background Embedding geriatric medical expertise in the emergency department (ED) is proposed to improve care for older people, yet the underlying mechanisms and context causing impact to remain poorly understood. Objective To develop programme theories explaining how, why, and under what conditions a geriatrician-led innovation model improves care for older people presenting to the ED. Methods We conducted a realist evaluation of a geriatrician-led innovation in the ED. Data were generated through non-participant observation, document review, interviews and focus groups with geriatricians, ED clinicians, surgical and general medicine teams. Analysis was abductive and retroductive, iteratively configuring data into context–mechanism–outcome configurations to produce programme theories. Results Sixteen interviews and five focus groups were conducted. We developed programme theories suggesting that embedding a geriatrician in the ED triggered timely disposition planning, strengthened care transitions, and fostered informal capability building. These outcomes arose through mechanisms of trust-building and boundary spanning, activated in contexts where specialist authority was recognised, trust with ED teams was established, and staffing capacity was sufficient. Limited after-hours coverage and competing ED priorities constrained these mechanisms, resulting in the deferral of some treatment and disposition decisions to the geriatrician, reducing intended efficiencies of timely and coordinated care. Conclusions This study advances understanding of how a geriatrician-led innovation model in an ED improve care delivery for older people by identifying the mechanisms and contextual conditions that shape their impact. The theories developed offer a foundation for ongoing theory building, requiring continued testing and refinement across diverse ED settings.
Yap et al. (Sun,) studied this question.