Many in healthcare today are interested in defining “quality improvement”. We propose defining it as the combined and unceasing efforts of everyone—healthcare professionals, patients and their families, researchers, payers, planners and educators—to make the changes that will lead to better patient outcomes (health), better system performance (care) and better professional development (learning; fig 1). This definition arises from our conviction that healthcare will not realise its full potential unless change making becomes an intrinsic part of everyone’s job, every day, in all parts of the system. Defined in this way, improvement involves a substantial shift in our idea of the work of healthcare, a challenging task that can benefit from the use of a wide variety of tools and methods (table 1).

Although all improvement involves change, not all changes are improvement. If healthcare is going to benefit fully from the science of disease biology, we need to be sure that the changes we make …