QI can be defined as a standard of care for all appropriate patients, and must be developed in a standardized, evidence-based way. 1,2 In 2000, the American College of S troke is the 4th leading cause of death, and a leading cause of disability, in Japan, but there is no national consensus on how best to measure quality indicators (QIs) of acute ischemic stroke (AIS). In the USA, several healthcare organizations have undertaken initiatives aimed at measuring and improving the quality of acute stroke care.