1Family Health Service, Department of Health, Room 1308, 13/F, Guardian House, 32 Oi Kwan Road, Wanchai, Hong Kong, China2Department of Applied Social Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong, China3Department of Community Medicine, The University of Hong Kong, 5/F William MW Mong Block, Room 5-05, 21 Sassoon Road, Hong Kong, China4Kwai Chung Hospital, 3-15 Kwai Chung Hospital Road, Kwai Chung, N.T., Hong Kong, China5Castle Peak Hospital, 15 Tsing Chung Koon Road, Tuen Mun, N.T., Hong Kong, China6Department of Psychiatry, United Christian Hospital, 130 Hip Wo Street, Kwun Tong, Kowloon, Hong Kong, China7Department of Psychiatry, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, N.T., Hong Kong, China