Department of Medicine and Geriatrics, Caritas Medical Centre, Sham Shui Po, Hong Kong. Department of Medicine and Geriatrics, Tai Po Hospital, Tai Po, Hong Kong. Department of Medicine, Hong Kong Buddhist Hospital, Lok Fu, Hong Kong. Department of Medicine and Geriatrics, Princess Margaret Hospital, Lai Chi Kok, Hong Kong. Department of Medicine and Therapeutics, Prince of Wales Hospital, Shatin, Hong Kong. Department of Medicine and Geriatrics, Tuen Mun Hospital, Tuen Mun, Hong Kong. Department of Medicine, Queen Elizabeth Hospital, Jordan, Hong Kong. Department of Medicine and Geriatrics, Pok Oi Hospital, Yuen Long, Hong Kong.