Advance Care Planning Motivators Among Adults With Serious Illness.

Importance: Advance care planning (ACP) engagement is poorly understood among people with serious illness. Objective: Determine whether diagnosis of and worries about serious illness are associated with ACP engagement. Design, Setting, and Participants: This cross-sectional study was based on a nationally representative survey administered April to May 2021 online or by telephone. Eligible participants were adults and English or Spanish language. Data were analyzed May 2023 to February 2025). Exposure: Having a serious illness. Main Outcomes and Measures: Three domains of ACP engagement: discussion with people close to participants, discussion with clinicians, and documentation in writing. Barriers to ACP documentation and worries about serious illness were also assessed. Survey responses were weighted to reflect the US Census population. χ2 tests and multivariable logistic regression models were adjusted for covariables to assess associations between serious illness and each ACP outcome. Results: Among 1854 participants (468 [weighted percentage, 25.2%] aged 65 years or older; 955 women [weighted percentage, 51.9%]; 193 Black [weighted percentage, 12.0%], 288 Hispanic [weighted percentage, 16.7%], 1218 White [weighted percentage, 61.2%]), 367 (weighted percentage, 20%) had serious illness. Overall, 1254 (weighted percentage, 65.9%) had engaged in ACP (283 of 367 [weighted percentage, 76.5%] serious illness vs 971 of 1487 [weighted percentage, 62.6%] without serious illness; P < .001); 1071 (weighted percentage, 55.3%) discussed ACP with people close to them, 462 (weighted percentage, 22.5%) discussed with clinicians, and 650 (weighted percentage, 32.8%) documented a surrogate. People with serious illness had higher odds than those without having discussed choices for surrogates and medical wishes with people close to them (aOR, 1.57 [95% CI, 1.19-2.07] and 1.66 [95% CI, 1.26-2.19]) and with clinicians (aOR, 2.16 [95% CI, 1.63-2.88] and 2.22 [95% CI, 1.67-2.94]). Serious illness status was not associated with ACP documentation. The most common barriers to documentation were not having thought about it (489 of 1171 [weighted percentage, 43.1%]) and assuming surrogates would know what they want (369 of 1171 [weighted percentage, 32.2%]). Participants who were worried (vs not worried) about being able to afford care, surrogates making the best or right decisions, having access to the best treatments, or having high stress or symptoms had significantly higher rates of ACP engagement. Conclusions and Relevance: In this survey study of adults in the US, we found that ACP discussions with someone close to them were high, yet discussions with clinicians and documentation were low, even among people with serious illness. Our findings offer insights into how people's worries about serious illness care may affect their engagement in ACP, and how to leverage these insights to tailor patient-facing messaging about ACP.