1. Bankstown-Lidcombe Hospital, New South Wales, Australia
2. South Western Sydney Clinical School, University of New South Wales, Australia
3. Correspondence: Yang Guo, FAFRM (RACP) MBBS MPH, Department of Aged Care and Rehabilitation, Bankstown-Lidcombe Hospital, South Western Sydney Clinical School, University of New South Wales, Locked Mail Bag 1600, Bankstown NSW 2200, Australia. Telephone (02) 9722 7558, Fax (02) 9722 8275,