Large language models (LLMs) have been increasingly adopted to support patients' healthcare-seeking in recent years. While prior patient-centered studies have examined the capabilities and experience of LLM-based tools in specific health-related tasks such as information-seeking, diagnosis, or decision-supporting, the inherently longitudinal nature of healthcare in real-world practice has been underexplored. This paper presents a four-week diary study with 25 patients to examine LLMs' roles across healthcare-seeking trajectories. Our analysis reveals that patients integrate LLMs not just as simple decision-support tools, but as dynamic companions that scaffold their journey across behavioral, informational, emotional, and cognitive levels. Meanwhile, patients actively assign diverse socio-technical meanings to LLMs, altering the traditional dynamics of agency, trust, and power in patient-provider relationships. Drawing from these findings, we conceptualize future LLMs as a longitudinal boundary companion that continuously mediates between patients and clinicians throughout longitudinal healthcare-seeking trajectories.

翻译：近年来，大型语言模型（LLMs）在支持患者就医方面的应用日益增多。尽管先前以患者为中心的研究已经探讨了基于LLM的工具在特定健康相关任务（如信息查询、诊断或决策支持）中的能力与体验，但真实世界实践中医疗保健固有的纵向特性尚未得到充分探索。本文通过一项为期四周、涉及25名患者的日记研究，考察了LLMs在整个就医轨迹中所扮演的角色。我们的分析表明，患者不仅将LLMs整合为简单的决策支持工具，更将其视为动态的陪伴者，在行为、信息、情感和认知层面为其就医旅程提供支持。同时，患者主动赋予LLMs多样的社会技术意义，从而改变了医患关系中关于能动性、信任与权力的传统动态。基于这些发现，我们将未来的LLMs概念化为一种纵向边界陪伴者，在整个纵向就医轨迹中持续地在患者与临床医生之间进行调解。