BackgroundThe influence of demographic factors on the completion and knowledge of the Portuguese Advance Directives (PAD) and the Health Care Proxy’s (HCP) role is still not clear.ObjectivesTo identify sociodemographic features associated with knowledge and adherence to PAD and HCP in palliative care.DesignCross-Sectional analysis of the sociodemographic data, PAD and HCP role knowledge, and PAD Register from a group of Portuguese palliative patients and their caregivers enrolled on the DAVPAL trial to test the PAD efficacy in promoting better concordance between patients and caregivers.ParticipantsOne hundred twenty participants (60 palliative patients and 60 caregivers).MethodsAfter enrollment, the participants' sociodemographic data was acquired, their knowledge of PAD and the role of an HCP was questioned, and their prior register of the PAD was asked.Results60 patients and 60 caregivers were included (n=120), with differences among them regarding age (p<.001), gender (p=.003), education (p<.001), job (p<.001), marital status (p=.043), and access to the internet (p=.003), but not regarding religion (p=.21). Only 13.3% of the participants were aware of PAD, 15.0% were aware of the HCP role, and 5.0% had previously filled a PAD. Religious beliefs (Non-Catholic) were the only sociodemographic factor significantly related to these three topics.ConclusionsThere is low awareness of PAD and the HCP’s role in palliative care, and there is higher knowledge on these topics among non-Catholic individuals. End-of-life decisions seem to be influenced by similarities in religious beliefs between patients and HCP. Improving education is necessary, namely in palliative care.Trial registrationClinicalTrials.gov IDNCT05090072. Retrospectively registered on 22/10/2021.