Fig. 1

Study Design of Facility Survey and Physician Survey of Physicians’ Working Condition (Hospital). Two surveys were conducted: a facility survey to be answered by the facility staff and a physician survey to be answered by the physicians. For the facility survey, hospitals received a request for cooperation from the research team and were asked to respond by mail. For the physician survey, physicians received a request for cooperation through their hospitals and were asked to respond directly by mail or via a dedicated survey website of their choice. The facility survey was sent to all hospitals in Japan (n = 8,173). The physician survey was sent to all physicians (estimated n = 108,237) working in 50% of randomly selected hospitals (n = 4,087).