Background Advance care planning (ACP) is a process that ideally leads to the writing of advance directives (ADs). The ACP process can be explained using the TransTheoretical Model (TTM), which describes the consecutive stages of intentional change (precontemplation, contemplation, preparation, action and maintenance) that individuals follow before engaging in a target health behavior. We investigate how involvement in the different stages toward AD completion predicts actual AD adoption over a four-year period.

Method We use data from waves 6 (2015) and 8 (2019/2020) of the Swiss component of the longitudinal Survey of Health, Ageing and Retirement in Europe (SHARE). We explore the involvement of three attitudinal measures (regular thinking about end-of-life (EOL) wishes; having discussed EOL preferences; planning to make ADs in the future) in the adoption of ADs among adults ages 55 and over (n=903) using multivariable probit regressions and controlling for contextual factors.

Results Among respondents who did not have an AD at wave 6, 30% reported completing an AD at wave 8. The three attitudinal measures were positively associated with AD adoption at wave 8. Introducing all three attitudinal measures simultaneously into the regression showed that only having discussed EOL preferences and planning to make ADs in the future remain statistically significantly associated with AD adoption in wave 8.

Conclusion Consistent with the TTM, the adoption of ADs follows a process in which the motivation and readiness of individuals to engage in a new behaviour appear to be paramount.