Trial analysis by treatment allocated or by treatment received? Origins of 'the intention-to-treat principle' to reduce allocation bias: part 2

By the late 1950s, the key role played by the Medical Research Council (MRC) in the development of controlled clinical trials – and of Hill’s leadership specifically – had become widely recognised. The example that had been set by the MRC during the 1950s led the Council for International Organizations of Medical Sciences (CIOMS) to invite Hill to plan and chair a conference on ‘Controlled Clinical Trials’. The conference was convened under the joint auspices of the UN Educational, Scientific and Cultural Organisation (UNESCO) and the World Health Organization (WHO) ‘to discuss the principles, organization and scope of “controlled clinical trials”, which must be carried out if new methods or preparations used for the treatment of disease are to be accurately assessed clinically