Background Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with pain, fatigue, functional limitations, and reduced quality of life. As more people live to older age with RA, age-related vulnerability such as frailty becomes increasingly relevant and may amplify functional decline, multimorbidity, and reliance on others. Informal caregivers (unpaid family members, friends, or neighbors) often provide substantial practical, emotional, and coordination support, yet caregiver needs are frequently overlooked in rheumatology care. INSPIRE (INtervention to Support Partners and Informal caREgivers of frail RA patients) is an individually tailored support intervention developed using the UK Medical Research Council framework for complex interventions and an iterative co-creation process involving older adults with RA and frailty, caregivers, healthcare professionals, and social care stakeholders. Before a definitive evaluation, feasibility and acceptability in routine care must be established.

Aim To evaluate the feasibility and acceptability of delivering INSPIRE in routine rheumatology care and to test study procedures in preparation for a future definitive trial.

Methods This is a single-arm feasibility study recruiting 25 informal caregivers of older adults with RA and frailty. Recruitment will occur within a fixed four-month window (1 March-1 July 2026) and will not be extended. Care recipients (older adults) will be ≥65 years with RA and frailty classified as Clinical Frailty Scale (CFS) 4-7. Caregivers will be ≥18 years, provide unpaid support, and report at least moderate burden defined as a Caregiver Burden Scale (CBS) mean score >1.99 at screening. Participants will be recruited from Rigshospitalet (Center for Rheumatology and Spine Diseases) and rheumatology departments in Køge, Slagelse, and Holbæk. Identification uses routine patient-reported outcomes (DANBIO) with invitation of potentially frail patients (e.g., MDHAQ >1.0) followed by telephone screening and CFS assessment; eligible patients nominate a caregiver who is then screened using CBS.

Intervention INSPIRE is delivered by a trained healthcare professional over ~12 weeks and comprises three contacts: an initial consultation (60-90 min), a brief follow-up (15-30 min), and a final consultation (30-60 min). Content is tailored using a toolbox addressing validation of the caregiver role, emotional/practical support, education, communication, and navigation across health and municipal services. Involvement of the older adult in consultations is optional and based on preferences of both parties.

Outcomes Feasibility outcomes include recruitment (screened/eligible/consented), retention at 12 weeks, questionnaire completeness, and deliverability (session completion, mode, duration). Acceptability will be assessed post-intervention using the Acceptability of Intervention Measure and supplemented by brief acceptability/feasibility questions and qualitative interviews. Fidelity and tailoring will be documented using structured session notes. Exploratory outcomes include caregiver burden measured by Caregiver burden scale, quality of life measured by WHOQOL-BREF (caregiver and older adult), and physical function measured by MDHAQ .

Progression criteria Pre-specified criteria include approximately 50% recruitment of those approached, ≥85% retention, and high fidelity, reviewed using a trafficlight approach (go/amend/stop).

Ethics and dissemination Written informed consent will be obtained from both the older adult and the caregiver prior to baseline data collection, with separate consent for any study components each participant takes part in (e.g., consultations, interviews). Findings will be disseminated through peer-reviewed publication, conferences, and stakeholder summaries.

This study evaluates the feasibility and acceptability of delivering INSPIRE (INtervention to Support Partners and Informal caREgivers of frail RA patients) within routine rheumatology care and tests study procedures to inform a future definitive trial. INSPIRE is an individually tailored support intervention for informal caregivers of older adults with rheumatoid arthritis (RA) and frailty, developed through stakeholder co-creation and designed for implementation in standard outpatient workflows.

Potentially eligible care recipients are identified using routine patient-reported outcomes completed prior to clinic visits (DANBIO). Functional limitation scores (MDHAQ) are used as a pragmatic trigger for further screening. Interested patients are contacted for telephone screening including frailty classification using the Clinical Frailty Scale (CFS). When an eligible patient agrees, they nominate an informal caregiver who is contacted by the study team, provided study information, and screened for caregiver burden using the Caregiver Burden Scale (CBS). Recruitment occurs within a fixed, pre-specified recruitment period.

INSPIRE is delivered by trained healthcare professionals with rheumatology context and experience in psychosocial support and service navigation. The intervention is delivered over approximately 12 weeks and consists of three structured contacts: (1) an initial consultation (about 60-90 minutes), (2) a brief follow-up contact (about 15-30 minutes; typically telephone), and (3) a final consultation (about 30-60 minutes). Delivery mode is flexible (clinic, home, or telephone) to reflect real-world implementation.

The initial consultation follows a structured needs assessment guided by the caregiver's CBS profile and a semi-structured consultation framework to identify the caregiver's priority burden domains. The healthcare professional supports goal setting and action planning and selects relevant elements from a predefined INSPIRE toolbox. Toolbox elements may include validation of the caregiver role; psychoeducation and coping support; practical strategies to reduce day-to-day strain; communication support within the dyad and with services; RA- and frailty-relevant information; and navigation/signposting to health and municipal services (e.g., home care, assistive devices, respite options, social work pathways). The brief follow-up contact reviews progress, identifies barriers, and adjusts the action plan and toolbox elements as needed. The final consultation consolidates strategies used, reviews ongoing support needs, and supports planning for continued access to relevant services. The older adult with RA may optionally participate in selected consultations when preferred by both parties; the caregiver remains the primary intervention recipient.

Feasibility is assessed using descriptive metrics including screening and recruitment flow, retention through follow-up, completeness of questionnaire data, and intervention deliverability (sessions completed, timing, duration, and mode). Acceptability is assessed post-intervention using the Acceptability of Intervention Measure and supplemented by brief structured questions and qualitative interviews with caregivers (and optionally older adults and/or delivering professionals) to explore perceived usefulness and implementation barriers and facilitators. Intervention fidelity and tailoring are documented using structured session notes recording components delivered, toolbox elements selected, caregiver goals, and referrals/signposting.

Analyses are descriptive and focus on feasibility and process outcomes. Candidate outcome measures are summarized at baseline and follow-up to assess completeness and variability; exploratory pre-post changes may be presented without formal hypothesis testing. The intervention is considered low risk; discussions may elicit emotional discomfort, and participants may pause or discontinue at any time. Delivering professionals follow predefined signposting/referral pathways if significant distress is identified. Data are managed securely and reported in anonymized form in accordance with applicable data protection requirements.

Inclusion Criteria (Caregivers):

• Informal (unpaid) caregiver of an older adult with confirmed rheumatoid arthritis (RA)
• Aged ≥ 18 years
• Care recipient aged ≥ 65 years
• Able to provide informed consent
• Able to complete study questionnaires
• Reports at least moderate caregiver burden, defined as mean CBS score > 1.99 at screening (Caregiver Burden Scale)

Inclusion Criteria (Care Recipients):

• Aged ≥ 65 years
• Confirmed diagnosis of RA
• Meets frailty eligibility in routine care, defined as Clinical Frailty Scale (CFS) ≥ 5

Exclusion Criteria (Caregivers):

• Severe cognitive impairment preventing participation
• Acute mental health crisis
• Other circumstances making it impracticable to complete the intervention and follow-up assessments

Data will be shared upon reasonable request