[1] Bradford Royal Infirm, Patient Safety Translat Res Ctr, Bradford Inst Hlth Res, Duckworth Lane, Bradford BD9 6RJ, W Yorkshire, England
[2] Univ Leeds, Fac Med & Hlth, Sch Psychol, Leeds LS2 9JT, W Yorkshire, England
[3] Univ Leeds, Sch Comp, Leeds LS2 9JT, W Yorkshire, England
[4] Univ York, Dept Hlth Sci, York Trials Unit, ARRC Bldg, York YO10 5DD, N Yorkshire, England