Serious brain diseases and injuries affect not only the person who becomes ill or injured, but also their family. Relatives of people with acquired brain injury (ABI) or malignant brain tumor (MBT) often take on a major role in daily care, decision-making, and coordination across healthcare services. This role can include managing information, supporting rehabilitation, and acting as a link between hospital care and community rehabilitation. Many relatives report high levels of stress, uncertainty, and emotional burden, especially during transitions between care settings.

Despite recommendations for greater involvement of relatives, support for this group is often uneven and poorly coordinated across healthcare sectors. Relatives frequently experience lack of overview, limited guidance, and unclear expectations regarding their role. These challenges may increase caregiver burden and negatively affect both relatives' well-being and the continuity of care.

The PIRe 2.0 study aims to further test, and implement a structured intervention to support systematic involvement of relatives of people with ABI or MBT across hospital and community rehabilitation services. The intervention is designed as a "caregiver compass" that helps relatives understand their role, clarify their needs and wishes for involvement, and gain better overview of the care pathway.

PIRe 2.0 is delivered through a stepped-care model, which allows the level of support to be adjusted over time based on each relative's level of burden and support needs. All relatives receive basic information and screening for caregiver burden using the 4-item Zarit Burden Interview (ZBI-4). Relatives who show signs of increased burden are offered additional support in steps, ranging from structured conversations with nurses to extended cross-sector coordination and specialized support for relatives with high or complex needs. Decisions about stepping up or down are based on both screening results and clinical assessment to ensure flexibility and person-centered care.

The study includes two groups of relatives: an intervention group receiving support through the PIRe stepped-care model, and a control group receiving usual care only. A total of 160 relatives will participate. Data are collected at baseline, at transitions between hospital and community care, and three to six months after the intervention.

The primary outcome is change in caregiver burden, measured with the Caregiver Burden Scale (CBS). Secondary outcomes include relatives' roles and responsibilities, perceived support and involvement in care, and mental well-being, assessed using validated patient-reported outcome measures.

In addition to evaluating the effect of the intervention, the study examines how the PIRe model can be implemented and sustained in everyday practice across healthcare sectors. The results are expected to show whether a structured, stepped-care approach can reduce caregiver burden, improve coordination between hospital and community services, and support more coherent and secure care pathways for people with ABI or malignant brain tumor and their relatives.

Relatives of people with acquired brain injury (ABI) or malignant brain tumor (MBT, World Health Organization grade 3-4) play a central role in supporting patients throughout complex neurological care pathways. Both patient groups are characterized by multifaceted disease trajectories and substantial needs for coordination and support within the healthcare system. These demands are often associated with high caregiver burden among relatives. While ABI trajectories typically involve prolonged rehabilitation and long-term functional impairments, MBT is more often characterized by an acute, progressive, and life-threatening course. Despite these differences, relatives across both groups face considerable emotional, practical, and organizational challenges.

Even within well-developed healthcare systems, relatives continue to perform a large share of care and coordination tasks and frequently assume an informal caregiver role without sufficient professional support or clear coordination across sectors. This role is associated with increased risk of emotional distress, frustration, and reduced mental well-being. Although policies and guidelines recommend greater involvement of relatives, systematic and structured approaches to supporting relatives in clinical practice remain limited.

Transitions between hospital care and community-based rehabilitation represent a particularly vulnerable phase. Insufficient communication and lack of continuity across sectors are well-documented sources of burden for relatives. Studies show that breakdowns in communication during transitions increase the risk of uncertainty, misunderstandings, and experiences of exclusion. Relatives often describe acting as informal coordinators and intermediaries between healthcare sectors, a role that may substantially increase both practical and emotional strain, especially when expectations and responsibilities are unclear.

To address these challenges, the PIRe intervention was developed as a nurse-led, multicomponent approach aimed at strengthening early and meaningful involvement of relatives. The intervention combines structured conversations with relatives, diagnosis-specific information delivered in an accessible format (including digital access), and a peer-developed checklist to support navigation of the care pathway. Findings from a prior feasibility study demonstrated substantial variation in relatives' needs over time. Many relatives in the acute phase had limited capacity for intensive support, while the need for more targeted and sustained support often increased later in the disease trajectory. These findings highlighted the need for a systematic yet flexible organizational framework that can tailor support over time and ensure continuity across hospital and community settings.

A stepped-care approach provides an evidence-based framework for structuring support and involvement of relatives with the possibility of gradual escalation and de-escalation across sectors. PIRe 2.0 represents the next step as a real-world effectiveness and implementation study in which the PIRe intervention is delivered and evaluated as a scalable stepped-care model for systematic involvement of relatives in complex neurological care pathways.

The overall aim of the PIRe 2.0 study is to evaluate the effect of the PIRe intervention on caregiver burden among relatives of people with ABI or MBT when delivered through a stepped-care model. In parallel, the study aims to evaluate key implementation outcomes when the intervention is delivered across hospital departments and community rehabilitation services.

Design and Study Components PIRe 2.0 comprises two concurrent and complementary sub-studies. Both involve delivery of the PIRe intervention but serve different analytical purposes. Sub-study 1 evaluates the effectiveness of the intervention under real-world conditions, while Sub-study 2 focuses on the development, evaluation, and refinement of an implementation strategy and examines organizational embedding in hospital and municipal practice.

Stepped-Care Framework The stepped-care model constitutes the shared structural framework for both the effectiveness and implementation components. The model is centered on systematic screening and monitoring of caregiver burden using the 4-item Zarit Burden Interview (ZBI-4), a validated tool for identifying caregiver-related strain. Screening results, combined with clinical assessment, guide decisions regarding the appropriate level of support within the model.

ZBI-4 is applied across all steps of the model as both a screening and monitoring tool. Initial screening is conducted at the start of hospital admission, with repeated assessments during hospitalization, at sector transitions, and when clinical concern about changes in caregiver burden arises. Guideline-based threshold values are used to support decisions about escalating or de-escalating support while maintaining flexibility through clinical judgment. This approach is intended to ensure individualized and responsive care for relatives.

Recruitment and Study Population Relatives are recruited through convenience sampling from participating neurological, neurosurgical, and neurorehabilitation departments at collaborating hospitals. A total of 160 relatives are included, divided between an intervention group and a control group receiving usual care. A sequential inclusion design is used, where the control group is fully recruited and completed prior to initiation of the intervention group. This design minimizes risk of contamination and ensures that staff training and intervention implementation are completed before delivery of the intervention.

Data Collection and Analysis Data are collected at baseline, at transitions between hospital and community rehabilitation, and three to six months after intervention delivery. The study uses validated patient-reported outcome instruments to assess caregiver burden, roles and responsibilities, perceived support and involvement, and mental well-being. Electronic data collection is used throughout, with secure data management procedures in place.

Intervention effects are analyzed using linear mixed-effects regression models, allowing for evaluation of changes over time and accounting for repeated measurements. The primary outcome is change in caregiver burden, with secondary outcomes addressing functional roles, perceived support, and symptoms of anxiety and depression.

Implementation Evaluation The implementation component of PIRe 2.0 is guided by theory- and evidence-based frameworks and informed by experiences from the prior feasibility study. The implementation strategy is developed in close collaboration with clinical and municipal stakeholders and evaluated across multiple dimensions, including acceptability, appropriateness, feasibility, fidelity, penetration, and sustainability. The sequential study design facilitates stepwise testing and refinement of the implementation strategy prior to full-scale rollout in routine practice.

The implementation targets nurses in hospital departments and community rehabilitation services who are involved in care trajectories for patients with ABI or MBT and their relatives. Training, standardized manuals, and ongoing supervision are used to support consistent and high-quality delivery of the intervention.

Cross-Sector Collaboration and Context The study is anchored in close cross-sector collaboration between hospitals and municipal rehabilitation services and is conducted in both urban and rural settings. This allows evaluation of the intervention under varying organizational conditions and strengthens the generalizability of findings. The study is conducted during a period of significant structural healthcare reforms, requiring a high degree of flexibility to adapt to changing organizational contexts.

User and Public Involvement Relatives of people with ABI and MBT are involved through an advisory panel that contributes to refining intervention content, relevance, and interpretation of results. User involvement is documented systematically and embedded throughout the project to ensure alignment with relatives' needs and perspectives.

Ethics and Expected Impact The study is conducted in accordance with ethical principles and data protection regulations. Participation is voluntary, and data are handled confidentially.

PIRe 2.0 addresses a well-documented need for more systematic and coordinated involvement of relatives in complex neurological care pathways. By combining a stepped-care model with cross-sector collaboration, the study aims to reduce caregiver burden, strengthen continuity of care, and support sustainable implementation of a scalable model that can be integrated into routine clinical and municipal practice and adapted to other patient groups.

Inclusion Criteria

• Primary relative of an adult diagnosed with acquired brain injury (ABI) or malignant brain tumor (MBT), admitted to a participating hospital department.
• Formally identified as the primary relative by the patient.
• Aged ≥18 years.
• Ability to read, understand, and complete questionnaires in Danish.

Exclusion Criteria

• Insufficient proficiency in Danish to complete questionnaires and participate in structured conversations.
• Concurrent participation in another interventional study with a similar aim that may interfere with the present study.