BackgroundImplementing evidence that changes practice in emergency departments (EDs) is notoriously difficult due to well-established barriers including high levels of uncertainty arising from undifferentiated nature of ED patients, resource shortages, workload unpredictability, high staff turnover, and a constantly changing environment. We developed and implemented a behaviour-change informed strategy to mitigate these barriers for a clinical trial to implement the evidence-based emergency nursing framework HIRAID® (History including Infection risk, Red flags, Assessment, Interventions, Diagnostics, communication, and reassessment) to reduce clinical variation, and increase safety and quality of emergency nursing care.AimTo evaluate the behaviour-change-informed HIRAID® implementation strategy on reach, effectiveness, adoption, quality (dose, fidelity) and maintenance (sustainability).MethodsAn effectiveness-implementation hybrid design including a step–wedge cluster randomised control trial (SW-cRCT) was used to implement HIRAID® with 1300 + emergency nurses across 29 Australian rural, regional, and metropolitan EDs. Evaluation of our behaviour-change informed strategy was informed by the RE-AIM Scoring Instrument and measured using data from (i) a post HIRAID® implementation emergency nurse survey, (ii) HIRAID® Instructor surveys, and (iii) twelve-week and 6-month documentation audits. Quantitative data were analysed using descriptive statistics to determine the level of each component of RE-AIM achieved. Qualitative data were analysed using content analysis and used to understand the ‘how’ and ‘why’ of quantitative results.ResultsHIRAID® was implemented in all 29 EDs, with 145 nurses undertaking instructor training and 1123 (82%) completing all four components of provider training at 12 weeks post-implementation. Modifications to the behaviour-change informed strategy were minimal. The strategy was largely used as intended with 100% dose and very high fidelity. We achieved extremely high individual sustainability (95% use of HIRAID® documentation templates) at 6 months and 100% setting sustainability at 3 years.ConclusionThe behaviour-change informed strategy for the emergency nursing framework HIRAID® in rural, regional, and metropolitan Australia was highly successful with extremely high reach and adoption, dose, fidelity, individual and setting sustainability across substantially variable clinical contexts.Trial registrationANZCTR, ACTRN12621001456842. Registered 25 October 2021.