[1] Imperial Coll London, Sch Publ Hlth, Ageing Epidemiol Res Unit, London, England
[2] Imperial Coll London, Dept Primary Care & Publ Hlth, London, England
[3] Nanyang Technol Univ, Lee Kong Chian Sch Med, Ctr Populat Hlth Sci, Singapore, Singapore
[4] Imperial Coll London, Fac Med, Imperial Coll Healthcare NHS Trust, Publ Hlth Diectorate, London, England
[5] Imperial Coll London, Sch Pub Hlth, Dept Infect Dis Epidemiol, London, England