Frailty in heart failure (HF) patients contributes to poor outcomes, emphasizing the need for effective management. In many previous studies, frailty interventions have mainly targeted physical frailty or focused community-dwelling patients, neglecting the multidimensional needs of hospitalized individuals. As a frailty for HF patients need to include clinical, functional, cognitive, and social domains, nurses must assess it holistically and provide personalized support, especially during care transitions. This study aims to evaluate the effectiveness of a nurse-led, personalized health coaching program for hospitalized HF patients with frailty through a randomized controlled trial. This 12-week intervention program targets hospitalized HF patients with frailty. After screening frailty HF patients using validated tools such as Fried's phenotype (FP), Tilburg Frailty Indicator (TFI), participants will be randomly assigned to either an intervention or control group. The intervention group will receive personalized health services, including pre-discharge education and weekly telephone coaching, addressing clinical, functional, psycho-cognitive, and social frailty domains. Psychiatric support and community integration program will be provided as needed. The control group will receive standard care. Frailty, QoL, and clinical outcomes will be measured at baseline, 12 weeks, and 24 weeks. The primary outcomes will be improvements in frailty and QoL. Frailty will be measured both multidimensional and each of the four domains of frailty for HF patients. This study will clarify the role of multidimensional personalized interventions in addressing adverse outcomes related to frailty in patients with HF, thereby providing evidence of their necessity in its management.

The prevalence of heart failure (HF) is increasing worldwide, and consistently in Korea, it has more than tripled between 2002 and 2020. As a result, the hospitalization rate due to HF has increased by 1.6 times, and the age-standardized mortality rate by more than fivefold. Despite the implementation of various treatment and management strategies, hospitalizations, unplanned visits and mortality related to HF continue to rise, underscoring the urgent need for multidimensional and personalized approaches to patient care. Particularly in Korea, the prevalence of HF begins to rise in an individual's 30s, and shows a significant increase after the age of 40s, with mortality rates gradually upward among middle-aged patients. Thus, there is the need to focus on health care among patients aged 40 and over.

One of the most common and critical issues observed in patients with HF is frailty. In HF, frailty is defined as a multidimensional, dynamic, and potentially reversible condition that, although age-related, is distinct from aging, that increases susceptibility to stressors and adverse outcomes. The overall prevalence of frailty among HF patients is estimated round 44.5%, although varying among measurement tools. Patients with frailty and HF exhibit a higher risk of cardiovascular death, HF-related hospitalization, all-cause death, and all-cause hospitalization as well as a lower quality of life (QoL). Although frailty is often age-related, it is not exclusive to the elderly, making frailty assessment essential for all patients with HF. Most existing frailty assessment tools emphasize only physical aspects and fail to capture the complexity of frailty in HF patients. Therefore, it is essential to plan and evaluate patients care using a multidimensional approach encompassing clinical, functional, cognitive-psychological, and social domains, as recommended by HF associations, which may help prevent or reduce adverse clinical outcomes.

According to the research results conducted so far, the evidence that multidimensional interventions more effectively improve frailty than single-domain interventions have been consisted, and a variety of healthcare professionals have delivered collaborative interventions to improve frailty. Among theses, nurse-led multidimensional interventions for community-dwelling older adults have shown improvements in frailty, physical function, nutritional status, QoL, social support, and mental health including reduced depression. In inpatient settings, nurses might play a key role in multidisciplinary teams as skilled health professional, educators, care coordinators, patient advocates, and liaisons. Therefore, HF nurses are able to plan and implement personalized interventions tailored to patients' individual needs in a central role.

The period from hospital admission to discharge is the most appropriate time to plan transition from hospital to home and a critical window for multidisciplinary intervention with HF patients. During hospitalization, above all else patients are at a high-risk stage of HF progress and frailty, and so early identification and fast management of HF progress are crucial. But most multidimensional interventions for frailty in HF have been conducted in community-based settings with no connection from the time of hospitalization. Hospital HF nurses can closely monitor patients' frailty status, coordinate with the care team, and plan for effective care transitions post-discharge. A structured transitional care strategy can help HF patients to maintain health care management and prevent readmissions at home.

Health coaching has emerged as an effective, goal-oriented, and patient-centered approach to support post-discharge self-care and behavior modification. After discharge interventions through phone calls, home visits, outpatient visit, or remote monitoring are essential components of HF management programs. A meta-analysis found that telecoaching has a significant impact on health outcomes, improving self-care and QoL in patients with HF. One study demonstrated that a 3-month personalized coaching program significantly reduced emergency visits and 6-month readmission rates, highlighting the importance of time in effecting behavioral change. Another study indicated that while younger patients prefer mobile or text-based interventions, older adults are more inclined to use telephone coaching in combination with paper-based health summaries. Thus, telephone coaching with paper manual book might be a particularly effective intervention for older, frail HF patients.

This study aims to present a protocol for evaluating the effects of a personalized telephone-based health coaching program on frailty, health-related QoL, and clinical outcomes among older patients hospitalized with heart failure. The findings are expected to contribute to the development of a practical, nurse-led inpatient intervention model that enhances the quality of HF patient care.

Inclusion Criteria:

• Participants aged 40 years or older will be included in the study, as heart failure (HF)-related mortality and the prevalence of HF increase significantly from this age onward. Inclusion criteria requires a diagnosis of acute HF by a cardiologist and hospitalization based on the following criteria: presence of HF symptoms (e.g., breathlessness, fatigue, ankle swelling) and signs (e.g., elevated jugular venous pressure, pulmonary crackles, peripheral edema), evidence of pulmonary congestion or edema on chest X-ray, and elevated levels of BNP (≥100 pg/mL) or NT-proBNP (≥300 pg/mL). After initial screening for frailty using both the Tilburg Frailty Indicator (TFI) and Fried's Phenotype (FP), participants will be enrolled if they are classified as frail, able to cooperate with functional assessments, and willing to provide written informed consent with a clear understanding of the study's purpose and procedures.

Exclusion Criteria:

• The exclusion criteria were as follows: current enrollment in other programs or planning to participate in similar programs during the intervention period; residing outside Korea and not understanding Korean; diagnosis of dementia with the Global Deterioration Scale stage of 5 or greater; inability to comprehend the study purpose and content.