Ethics approval
An initial favourable ethical opinion was granted by NRES Committee East of England—Cambridge South: REC reference: 12/EE/0230 on 24 July 2012. US approvals: Cedars-Sinai Medical Center Institutional Review Board: Pro00031367; Cleveland Clinic Institutional Review Board: 13-666; Hospital for Special Surgery Institutional Review Board: 13114; Mount Sinai Hospital Research Ethics Board: 12-0231-A; St. Joseph’s Hospital Hamilton Integrated Research Ethics Board: 13-037; University of Pittsburgh Institutional Review Board: PRO13020329; University of Pennsylvania Office of Regulatory Affairs: 816166; The Mayo Clinic, University of Michigan, University of North Carolina and the University of Utah all deferred to the University of Pennsylvania Ethics board and fall under the University of Pennsylvania approval number. Japanese ethics committee numbers: University of Miyazaki 2013-126; Chiba University 97; Kitano Hospital P14-01-002; Okayama University m05002; Kyorin University H26-031; Teikyo University 14-031; TMGH 260201. Participants gave informed consent to participate in the study before taking part.