This multicentre study uses a mixed-methods approach to evaluate testing of a nurse-led care model intervention. Each of the 11 NHs participating in this study will recruit at least one registered nurse with at least three years' long-term care experience, which will undergo training to become a geriatric nurse expert. Training of the geriatric nurse experts will be delivered as a blended-learning approach, combining face to face (F2F) teaching and E-learning modules. The 8 modules will cover the following topics: 1. leadership, 2. communication, 3. comprehensive geriatric assessment, 4. geriatric syndromes, 5. chronic conditions, 6. acute conditions, 7. pharmacology in geriatrics and 8. quality improvement. Modules 1-3 and 8 will be delivered as 5 days of F2F teaching before the implementation start, followed by E-learnings, and 8 expert meetings to be continued throughout the intervention. The last meeting takes place in November 2019. Additionally, the practical training will be enhanced by individual supervision with an experienced nurse expert and/or geriatrician. Modules 4-7 will be delivered via E-learning modules. All modules will cover approximately 66h of F2F learning and 60 hours of E-learning, depending on the level of education and experience of each nurse. In total the geriatric nurse expert training should account for approximately 125 hours.

The registered nurse which will take on the role of geriatric nurse expert will either be recruited within the pool of nurses in each respective NH or recruited from the outside. The nurse-led care model will be built with core components, such as interprofessional collaboration, presence of a geriatric nurse expert, comprehensive geriatric assessment, advance care planning, guidance and coaching, data driven quality and evidence-based tools. Each NH will have to implement these core components along with implementing the role of geriatric nurse expert.

The intervention will be implemented and evaluated by means of a non-randomized quasi experimental stepped-wedge design, over a period of 21 months. The stepped wedge design allows inclusion of all NHs, thus does not exclude NHs from receiving the INTERCARE \| Research plan Version 1.1/09.05. 2018 20/53 intervention. The "stepped" or "graded" unidirectional allocation to the intervention enables each NH to act as its own control. After a 3-month baseline phase, NHs will sequentially begin implementation of the nurse-led care model, which they will continue to use post-implementation. A get-in period of 1 month will be planned to address possible timing problems at the intervention start. Another advantage of the design is the graded start in the NHs facilitating delivery of the intervention, as each NH will discuss with the research team when they will receive the intervention. The first two NHs will start their baseline data collection in June 2018 and implement the intervention in September 2018, and every month thereafter, two other NHs will start with the intervention.

A non-randomized design was chosen to enable NHs to choose when they will start with the intervention, to allow for each NH to prepare accordingly for the implementation. Limitations of this study design might arise from its novelty. So far, no gold standard for data analysis has been established. In addition to this, non-randomization of the starting point of the intervention may imply that NHs were prepared for the intervention and this may be reflected in the results.