Complex systems thinking in emergency medicine: A novel paradigm for a rapidly changing and interconnected health care landscape.

INTRODUCTION: The specialty of emergency medicine is experiencing the convergence of a number of transformational forces in the United States, including health care reform, technological advancements, and societal shifts. These bring both opportunity and uncertainty. 21ST CENTURY CHALLENGES: Persistent challenges such as the opioid epidemic, rising health care costs, misaligned incentives, patients with multiple chronic diseases, and emergency department crowding continue to plague the acute, unscheduled care system. REDUCTIONISM AND COMPLEX SYSTEMS THINKING: The traditional approach to health care practice and improvement-reductionism-is not adequate for the complexity of the twenty-first century. Reductionist thinking will likely continue to produce unintended consequences and suboptimal outcomes. Complex systems thinking provides a perspective and set of tools better suited for the challenges and opportunities facing public health in general, and emergency medicine more specifically. IMPLICATIONS FOR EMERGENCY MEDICINE: This article introduces complex systems thinking and argues for its application in the context of emergency medicine by drawing on the history of the circumstances surrounding the formation of the specialty and by providing examples of its application to several practice challenges.