Serving as an emerging and powerful tool, Large Language Model (LLM) - driven Human Digital Twins are showing great potential in healthcare system research. However, its actual simulation ability for complex human psychological traits, such as distrust in the healthcare system, remains unclear. This research gap particularly impacts health professionals' trust and usage of LLM - based Artificial Intelligence (AI) systems in assisting their routine work. In this study, based on the Twin-2K-500 dataset, we systematically evaluated the simulation results of the LLM-driven human digital twin using the Health Care System Distrust Scale (HCSDS) with an established human-subject sample, analyzing item-level distributions, summary statistics, and demographic subgroup patterns. Results show ed that the simulated responses by the digital twin were significantly more centralized with lower variance and had fewer selections of extreme options (all p<0.001) . While the digital twin broa dly reproduces human results in major demographic patterns, such as age and gender, it exhibits relatively low sensitivity in capturing minor differences in education levels. The LLMbased digital twin simulation has the potential to simulate population trends, but it also presents challenges in making detailed, specific distinction s in subgroups of human beings. This study suggests that the current LLM - driven Digital Twins have limitations in modeling complex human attitudes, which require careful calibration and validation before applying them in inferential analyses or policy simulations in health systems engineering. Future studies are necessary to examine the emotional reasonin g mechanism of LLMs before their use, particularly for studies that involve simulations sensitive to social topics, such as human-automation trust.

This evolution indicates an expansion from industrial uses into diverse fields, including healthcare [61], [59]. The core functionalities of digital twins include an accurate mirroring of their physical counterparts, capturing all associated processes in a data-driven manner, maintaining a continuous connection that synchronizes with the real-time state of their physical twins, and simulating physical behavior for predictive analysis [85]. In the context of healthcare, a novel extension of this technology manifests in the form of Human Digital Twins (HDTs), designed to provide a comprehensive digital mirror of individual patients. HDTs not only represent physical attributes but also integrate dynamic changes across molecular, physiological, and behavioral dimensions. This advancement is aligned with a shift toward personalized healthcare (PH) paradigms, enabling tailored treatment strategies based on a patient's unique health profile, thereby enhancing preventive, diagnostic, and therapeutic processes in clinical settings [44], [50]. The personalization aspect of HDTs underscores their potential to revolutionize healthcare by facilitating precise and individualized treatment plans that optimize patient outcomes [72]. Although the potential of digital twins in healthcare has garnered much attention, practical applications remain newly developing, with critical literature highlighting that many implementations are still in exploratory stages [59]. Notably, institutions like the IEEE Computer Society and Gartner recognize this technology as a pivotal component in the ongoing evolution of healthcare systems that emphasize both precision and personalization [31], [89].

Digital Twins (DTs) are a critical technology for digitalizing physical entities in domains ranging from industry to city planning [1, 2]. DTs' ability to continuously adapt to a physical entity's state, simulate future events, and actively influence feedback and decision processes, goes significantly beyond traditional digital models as merely representations [3]. Thus, Industry 4.0 has started using DTs--along with other cutting-edge technologies, such as the Internet of Things (IoT), Big Data, and Artificial Intelligence (AI)--to significantly increase the efficiency and safety of both products and processes [3]. Further, due to DTs' real-time monitoring and simulation capabilities, they are being increasingly adapted to domains such as healthcare to meet demands for individualized diagnostics and treatment [4].

So, here we are in 2021: The idea of digital twins is catching on among organizations who are looking for ways to improve their operations. Interestingly enough, though, there is a striking disconnect. The concept of twins is predominantly one that pertains to human beings. And yet the human factor thus far has not been represented adequately in this equation. This is even more surprising as experts assume that human workers account for 70 percent of the added value on the shop floor. Alongside this, many studies suggest that human hands will continue to play an important role in the Fourth Industrial Revolution (Industry 4.0).