Advance care planning is typically initiated during the last six months of a patient's life. However, due to the progressive decline in the decision-making process in individuals with dementia, their involvement in advance care planning is limited to the early stages of the disease. Currently, there is no consensus on the optimal timing for initiating advance care planning for people with dementia, and a comprehensive review of the literature addressing this matter is lacking.

To explore the experiences and perspectives of people with dementia, their family caregivers, and health care professionals with regard to the optimal timing for initiating advance care planning.

A meta-synthesis was conducted.

The following eight electronic databases were searched: PubMed, Embase, Web of Science, Cochrane Library, CINAHL and CNKI, WanFang and Vip.

This review uses thematic synthesis to systematically synthesize qualitative evidence and report findings according to The Enhancing Transparency in Reporting the Synthesis of Qualitative Research (ENTREQ) and the Joanna Briggs Institute Manual for Evidence Synthesis. Study selection and data extraction were conducted independently by two researchers, and quality was evaluated using the Joanna Briggs Institute's Qualitative Research Standard Assessment tool.

Twenty-one studies were selected for this review. This review involved an overarching theme: The utilization of pivotal elements to transition from delayed initiation to comprehensive implementation. Three themes emerge, including the prerequisites for initiating advance care planning, not ready to start advance care planning and struggling along narrow roads. For health care professionals, the selection of an opportune moment to initiate advance care planning for people with dementia is not only a challenge but also a crucial prerequisite for the successful implementation of advance care planning. Health care professionals' experience, attitude toward advance care planning, trust relationship with patients, cultural differences among people with dementia and their caregivers, and economic disparities all influence health care professionals' judgment of the timing for initiating advance care planning.

Determining the optimal timing for initiating advance care planning is a complex process that requires a comprehensive consideration of the realities faced by health care professionals, people with dementia and their caregivers. Therefore, it is imperative to provide relevant training to health care professionals to ensure the successful implementation of advance care planning.