[1] Univ Leeds, Bradford Teaching Hosp NHS Fdn Trust, Bradford Inst Hlth Res, Acad Unit Ageing & Stroke Res, Duckworth Lane, Bradford BD9 6RJ, England
[2] Univ Leeds, Leeds, England
[3] Bradford Teaching Hosp NHS Fdn Trust, Bradford Inst Hlth Res, Born Bradford, Bradford, England
[4] Univ York, Dept Hlth Sci, York, England