The National Institute for Health Research (NIHR) is the research arm of the NHS and is funded through the Department of Health and Social Care to improve the health and wealth of the nation through research. It is a large, multi-faceted and nationally distributed organisation. Together, NIHR people, facilities and systems represent the most integrated clinical research system in the world.   NIHR is the largest single funder of Cochrane, and currently supports  21 Cochrane Review Groups based in England.