Shifting Public Discourse on Life-Sustaining Treatment in South Korea From 2014 to 2025: Longitudinal Social Media Analysis.

Background: Public discourse plays an important role in shaping how end-of-life care and medical decision-making are understood within society. In South Korea, the implementation of the Life-Sustaining Treatment Decision Act in 2018 established a legal framework for withholding or withdrawing life-sustaining treatment for patients at the end of life. However, relatively little is known about how public discourse surrounding life-sustaining treatment has evolved over time, particularly before and after the act's implementation. Objective: This study aimed to examine how online discourse related to life-sustaining treatment in South Korea evolved using large-scale social media data by identifying dominant themes, tracing their temporal changes from 2014 to 2025, and assessing shifts in sentiment before and after the act. Methods: A total of 16,191 text documents, comprising posts from Naver blogs, Naver cafes, and comments from YouTube, were collected using keywords related to life-sustaining treatment and end-of-life decision-making. Text was preprocessed using the Kiwi tokenizer for Korean morphological analysis, and latent Dirichlet allocation topic modeling was applied to extract underlying themes. A 6-topic solution was selected based on topic coherence and interpretability. Temporal changes in topic prevalence were examined across the study period, and topic distributions were compared between the prelaw (2014-2017) and postlaw (2018-2025) periods. Sentiment analysis was conducted using the Kunsan National University Korean sentiment lexicon to classify documents into positive, neutral, and negative categories. A study-defined descriptive net sentiment change index was calculated to summarize changes in positive and negative sentiment following policy implementation. Results: Six major themes were identified: death with dignity, hospice and palliative care, aging and social care, end-of-life decision-making, euthanasia debate, and withdrawal of treatment. Discourse volume increased more than 17-fold over the study period. Prior to 2018, discussions were dominated by end-of-life decision-making (255/573, 44.5%) and withdrawal of treatment (178/573, 31.1%). Around the time of policy implementation, ethical and legal debates became more prominent. In subsequent years, discourse increasingly reflected care-oriented perspectives, including hospice and palliative care and aging and social care. Sentiment improved most markedly for end-of-life decision-making and hospice and palliative care following the act, whereas aging and social care showed minimal change, and death with dignity exhibited a decline in net sentiment. Conclusions: Public discourse on life-sustaining treatment in South Korea evolved from a clinical focus to ethical debate and, more recently, to care-oriented perspectives. These changes were temporally associated with the implementation period of the Life-Sustaining Treatment Decision Act but should not be interpreted as causal effects of the legislation. The findings highlight the value of social media data for monitoring policy-associated changes in public discourse on end-of-life care.