With the increase in the older population, the number of people with dementia (PWD) is also increasing. There are nearly 10 million newly diagnosed cases of dementia every year, or one new case every 3.2 s worldwide (Alzheimer's Disease International, 2022). The total cost of dementia care as a proportion of GDP has been reported to range from 0.2 % to 1.4 % globally, which has a great impact on the psychological, social and economic aspects of society (Alzheimer's Disease International, 2022). Dementia is usually considered to progress slowly as far as the quality of care is concerned, and the issue of advance care planning (ACP) is considered to be one of the most important care issues for PWD at the end of their lives (Brazil et al., 2018; Livingston et al., 2017). ACP is a process designed to help individuals understand and align their personal values, life goals, and preferences regarding future healthcare (Bryant et al., 2019; Korfage et al., 2020; Wendrich-van Dael et al., 2020). ACP becomes especially crucial when individuals anticipate a decline in health due to illness (Wendrich-van Dael et al., 2020). Research from western countries highlights several benefits of ACP, including improved quality of life, increased referrals to palliative care, higher rates of advance directive (AD) completion, and reduced end-of-life hospitalizations and medical costs (Bryant et al., 2019; Korfage et al., 2020; Wendrich-van Dael et al., 2020).

Despite the recognized importance of ACP, its implementation in Asia faces substantial challenges due to cultural taboos surrounding discussions about death, particularly with older family members. Many elders believe that talking about death brings bad luck and may hasten their demise (Ho et al., 2021; Lee et al., 2024; Martina et al., 2021). Additionally, Chinese culture, one of the most collectivistic in Asia, emphasizes family-centered decision-making in healthcare contexts (Lee et al., 2014; Lee et al., 2024; Lin et al., 2019). The principle of filial piety, which dictates that children should care for their parents unconditionally, can hinder open communication about a diagnosis, poor prognosis, and the implementation of ACP (Lee et al., 2024). Thus, ACP completion rates in western countries range from 8 % to 36.7 % among adults (Sato et al., 2011; Yadav et al., 2017), in stark contrast to significantly lower rates of 2 % in Japan and <0.1 % in Taiwan (Ministry of Health and Welfare, 2023; Sato et al., 2011).

Studies in the United States and Taiwan found that PWD rely on others' care at the end stage of disease, and the majority die in long-term care facilities (Forbes et al., 2004; Lee et al., 2024; National Health Research Institute, 2024). Cognition and self-care ability change as the disease progresses, so the decision-making ability of PWD is affected (Tilburgs et al., 2018; Wendrich-van Dael et al., 2020). Most healthcare providers indicate the need to improve the quality of end-of-life care for PWD, and ACP allows healthcare providers to respect their choices (Bally et al., 2020; Bollig et al., 2016; Brazil et al., 2015). However, systematic integrative reviews and our previous studies in long-term care facilities in Taiwan reveal that many healthcare providers lack adequate understanding and experience with ACP and struggle with managing different opinions among family members (Chao et al., 2025; Lin et al., 2025; Tilburgs et al., 2018). These studies underscore the need for in-service education, health education, and the Patient Decision Aids (PDAs) tailored for healthcare providers in assisting PWD and their families (Brazil et al., 2018; Chao et al., 2025; Lin et al., 2025).

As dementia progresses, the role of families of PWD changes from assisting with making a decision to becoming the main decision makers. When families of PWD make an end-of-life decision for their demented family members, they need a healthcare provider's assistance in processing their difficulties and painful emotions to their love ones, understanding the trajectory of disease, and whether their decisions will affect the natural course of the disease (Forbes et al., 2004; Wendrich-van Dael et al., 2020). Hence, developing appropriate tools to help the healthcare providers to discuss the decision-making process with these families and PWD is important (Miyanaga & Poudyal, 2019; Tilburgs et al., 2018). The PDAs thus can be a valuable tool for healthcare providers in facilitating effective communication with PWD and their families to make informed and appropriate decisions regarding their care (Brazil et al., 2015; Coulter et al., 2013). Therefore, five main considerations for PWD and their family members making medical decisions for PWD are concerned: affection for the patient, values and goals for treatment of a terminal disease, lifestyle changes due to a disease, positive and negative views on death, and recognition of the unknown track of death (Forbes et al., 2004). Our research team focuses on six critical factors when developing PDAs: (1) the health literacy of the patients and their families; (2) using plain language to explain concepts and less medical jargon; (3) using photos to illustrate concepts; (4) using concise phrases to increase understandability and repeat key points; (5) using demonstrations to enforce what they learn; and (6) respectful and caring attitudes towards patients in every communication to facilitate their understanding (Williams et al., 2002). These factors ensure that PDAs are accessible, comprehensible, and supportive, and thus PDAs can enhance the decision-making process for family members and individuals with dementia.

The PDAs is designed to help healthcare providers empower PWD and their families to actively participate in end-of-life care decisions. The PDAs offers structured guidance, informing them of the benefits, risks, outcomes, and context of various care options (Florin et al., 2008; Harrison Dening et al., 2019; Korfage et al., 2020; Wendrich-van Dael et al., 2020). It also helps PWD clarify their values, understand how decisions may affect their quality of life, and make choices aligned with their preferences. This study aims to develop practical and accessible PDAs tailored to the needs of PWD and their families. The research hypothesis of this study is as follows: The newly developed PDAs will demonstrate: (1) High validity, with a Content Validity Index (CVI) ≥ 0.80; (2) High quality and effectiveness, with scores for understandability and actionability ≥0.80; (3) Comprehensiveness and usability when used by experts, and acceptability and usability when used by users with scores ≥0.80; (4) Effective support in preparing users for end-of-life care decision-making with scores ≥0.80.