Large AI Models in Health Informatics: Applications, Challenges, and the Future.

Large AI models, or foundation models, are models recently emerging with massive scales both parameter-wise and data-wise, the magnitudes of which can reach beyond billions. Once pretrained, large AI models demonstrate impressive performance in various downstream tasks. A prime example is ChatGPT, whose capability has compelled people's imagination about the far-reaching influence that large AI models can have and their potential to transform different domains of our lives. In health informatics, the advent of large AI models has brought new paradigms for the design of methodologies. The scale of multi-modal data in the biomedical and health domain has been ever-expanding especially since the community embraced the era of deep learning, which provides the ground to develop, validate, and advance large AI models for breakthroughs in health-related areas. This article presents a comprehensive review of large AI models, from background to their applications. We identify seven key sectors in which large AI models are applicable and might have substantial influence, including: 1) bioinformatics; 2) medical diagnosis; 3) medical imaging; 4) medical informatics; 5) medical education; 6) public health; and 7) medical robotics. We examine their challenges, followed by a critical discussion about potential future directions and pitfalls of large AI models in transforming the field of health informatics.

Supervised-actor-critic reinforcement learning for intelligent mechanical ventilation and sedative dosing in intensive care units.

BACKGROUND: Reinforcement learning (RL) provides a promising technique to solve complex sequential decision making problems in healthcare domains. Recent years have seen a great progress of applying RL in addressing decision-making problems in Intensive Care Units (ICUs). However, since the goal of traditional RL algorithms is to maximize a long-term reward function, exploration in the learning process may have a fatal impact on the patient. As such, a short-term goal should also be considered to keep the patient stable during the treating process. METHODS: We use a Supervised-Actor-Critic (SAC) RL algorithm to address this problem by combining the long-term goal-oriented characteristics of RL with the short-term goal of supervised learning. We evaluate the differences between SAC and traditional Actor-Critic (AC) algorithms in addressing the decision making problems of ventilation and sedative dosing in ICUs. RESULTS: Results show that SAC is much more efficient than the traditional AC algorithm in terms of convergence rate and data utilization. CONCLUSIONS: The SAC algorithm not only aims to cure patients in the long term, but also reduces the degree of deviation from the strategy applied by clinical doctors and thus improves the therapeutic effect.

Incorporating causal factors into reinforcement learning for dynamic treatment regimes in HIV.

BACKGROUND: Reinforcement learning (RL) provides a promising technique to solve complex sequential decision making problems in health care domains. However, existing studies simply apply naive RL algorithms in discovering optimal treatment strategies for a targeted problem. This kind of direct applications ignores the abundant causal relationships between treatment options and the associated outcomes that are inherent in medical domains. METHODS: This paper investigates how to integrate causal factors into an RL process in order to facilitate the final learning performance and increase explanations of learned strategies. A causal policy gradient algorithm is proposed and evaluated in dynamic treatment regimes (DTRs) for HIV based on a simulated computational model. RESULTS: Simulations prove the effectiveness of the proposed algorithm for designing more efficient treatment protocols in HIV, and different definitions of the causal factors could have significant influence on the final learning performance, indicating the necessity of human prior knowledge on defining a suitable causal relationships for a given problem. CONCLUSIONS: More efficient and robust DTRs for HIV can be derived through incorporation of causal factors between options of anti-HIV drugs and the associated treatment outcomes.