[1] Univ New S Wales, Ctr Primary Hlth Care & Equ, Sydney, NSW 2052, Australia
[2] Sydney S W Area Hlth Serv, Gen Practice Unit, Camperdown, NSW 2050, Australia
[3] Univ New S Wales, Sch Publ Hlth & Community Med, Sydney, NSW 2052, Australia
[4] Univ New S Wales, Ctr Primary Hlth Care, Sydney, NSW 2052, Australia