Development and Feasibility Assessment of an Intrinsic Capacity Program in Primary Care: Protocol for an Implementation Science Approach.

backgroundThe World Health Organization (WHO) public health framework for healthy aging advocates for action on the trajectories of intrinsic capacity (IC) across a person's life course to optimize functional ability. While the WHO integrated care for older people (ICOPE) framework provides guidance on a systematic care pathway on IC screening, clinical assessment to clarify IC deficits and person-centered management, its real-world implementation and evaluation remain nascent. The Intrinsic Capacity Promotion in Primary Care for the Frail (IMPACTFrail) program for mildly frail older adults in Singapore's primary care seeks to operationalize WHO ICOPE and national strategies.

objectiveThe objectives of this study are (1) the co-development of IMPACTFrail's core functions and its delivery, as well as selecting, specifying and operationalizing implementation strategies to address anticipated barriers and leverage anticipated facilitators and (2) to conduct a feasibility assessment on the readiness to scale to a main study.

methodsFor the first objective, the co-development process is guided by the United Kingdom Medical Research Council's (MRC's) framework for developing and evaluating complex interventions and the Framework of Actions for Intervention Development (FAID). The identification of contextual barriers and facilitators will draw on the updated Consolidated Framework for Implementation Research (CFIR) and its Outcomes Addendum. To identify individual-level behavior change barriers, we will extend this framework using the Theoretical Domains Framework (TDF). The Expert Recommendations for Implementing Change (ERIC) taxonomy guided our selection and development of implementation strategies. The collaboration involves implementation researchers, clinic leadership, frontline health care providers, and older adults. A 12-month, single-arm feasibility study will recruit 180 older adults aged 60 years and older with mild frailty (Clinical Frailty Scale score 4-5) across 5 public primary care clinics. Feasibility criteria include implementation, acceptability, practicality, and adaptability. We will narratively triangulate findings across study components to enhance the validity and credibility of the feasibility study, including (1) process evaluation using quantitative process indicators, (2) qualitative study to elicit barriers and facilitators to feasibility, sustainability and scalability, and to assess the attribution of the selected implementation strategies to implementation outcomes, (3) cost analysis, and (4) program description.

resultsThe study was funded in September 2024. Data collection for the feasibility assessment commenced in April 2025 and will conclude by March 2026. As of manuscript submission, 98 participants have been recruited across 5 sites. Recruitment, data collection, and analysis are ongoing. Publication of results is expected in early 2027.

conclusionsThis protocol contributes to the literature by providing a detailed protocol on the co-development and feasibility testing of a complex intervention to enhance transparency, fidelity, and replicability. It disseminates knowledge on the integration of frameworks and methodologies to accelerate the translation of evidence to sustainable and scalable programs in practice.

trial registrationClinicalTrials.gov NCT06753643; https://clinicaltrials.gov/study/NCT06753643. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/84257.