1. Division of Geriatric Medicine, Department of Medicine, National University Hospital, 1E Kent Ridge Road, Singapore 119228, Singapore
2. Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
3. Biostatistics Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119077, Singapore
4. Geriatrics Division, Department of Internal Medicine, Jundiai Medical School, Jundiai 13202-550, SP, Brazil