Patient-centered care involves treating patients in the way that is the most aligned with their values and their self-determination. This is the aim of Advance Care Planning (ACP), a communication-based complex intervention. ACP involves accompanied reflection about one's values, anticipation of potential health problems in future states of impaired decision-making capacity, consideration of a range of treatment and care options, anticipatory decision making and the documentation and communication of these decisions to family members and health care professionals. This process ensures that a person's self-determination is respected even when she is no longer able to make health care decisions. ACP programs are well established in the English-speaking world and are currently being developed across Asia and Europe.

Participation in ACP requires decision-making capacity. Yet, many people lose this capacity before having formally expressed their care preferences. In these cases, their health care proxies, families and health professionals are called upon to make decisions on their behalf, based on what they believe the person would have wanted (presumed will). This is problematic and distressing for both family members and health professionals. The fact that many people do not participate in ACP or complete advanced directives, along with an increasing prevalence of neuro-degenerative diseases entailing a loss of decision-making capacity, means that growing numbers of people are likely to require others to make medical decisions on their behalf.

The investigator's exploratory research, confirmed by the literature, highlights an urgent unmet need for comprehensive and systematic interventions to assist in promoting self-determination of older people who lack decision making capacity. ACP by proxy (ACP-bp) has been suggested as a model to help proxies of incapacitated patients plan ahead and prepare for future care decisions. However, this model has never been specifically developed nor tested. This is why the investigators have developed a specific model of ACP-bp and aim to test it in a pilot study among proxies of residential aged care facility (RACF) residents who lack decision making capacity, primarily due to advanced dementia.

The investigators aim to test the acceptability and feasibility of this intervention and the appropriateness of outcome measures through a pilot study in two RACFs in the Swiss canton of Vaud over a period of one year. A process evaluation will be conducted through the triangulation of mixed-method data: self-report scales, semi-structured interviews, document analyses, resident health care records and an economic cost analysis. This will form the basis for a subsequent cluster-randomized control trial to test the intervention's effectiveness. This novel approach of ACP-bp has potential to promote self-determination and patient-centered care that improves both the ethical appropriateness and economic sustainability of care. It may lead to patients being treated in accordance with their wishes, reduce unnecessary overtreatment and avoid distress for family members and health care professionals. This approach also responds to calls for models of ACP which can be used in people with dementia and people living in RACFs, vulnerable populations that have generally remained invisible in ACP research so far.