Advance care planning engagement and associated factors among adults without a family member they wish to designate as a surrogate decision-maker: a cross-sectional study

With population aging and a growing number of single-person households, ACP support for adults who perceive that they have no family member they wish to designate as a surrogate decision-maker is increasingly important, yet their ACP engagement remains poorly understood. This study aimed to describe its distribution and examine factors associated with whether formed preferences had been discussed, communicated, or documented. This cross-sectional web-based survey included adults aged ≥ 18 years in Japan who perceived that they had no family member they wished to designate as a surrogate. ACP engagement was classified into five stages: 1, no interest or prior consideration; 2, avoidance; 3, interest or an opportunity to consider ACP; 4, preferences formed but not shared; and 5, preferences discussed, communicated, or documented. Explanatory variables included perceived social support, perceptions of ACP, the number of ACP-related terms recognized, and medical experiences. Multinomial logistic regression treated the stages as nominal categories, and hierarchical binary logistic regression compared Stages 4 and 5. Among 719 participants (mean age, 53.7 years; 20.4% aged ≥ 65 years), 49 (6.8%) were classified as Stage 5; Stage 3 was most common (29.1%). Relative to Stage 5, more negative perceptions of ACP were associated with higher odds of Stages 1–4, more positive perceptions with lower odds of Stages 1 and 2, lower perceived social support with higher odds of Stages 2–4, and recognizing more ACP-related terms with lower odds of Stage 2 only. In the Stage 4–5 analysis, each 10-point increase in perceived social support was associated with higher odds of Stage 5 (aOR = 1.36, 95% CI 1.08–1.69), whereas hospitalization of a family member or close person was associated with lower odds (aOR = 0.34, 95% CI 0.15–0.74). Few participants had discussed, communicated, or documented their preferences. Among those with formed preferences, higher perceived social support was associated with these activities, whereas hospitalization of a family member or close person was associated with lower odds of Stage 5. ACP support should identify available sources of support and, when desired, facilitate discussion with trusted non-family persons or healthcare professionals.