[1] Univ So Queensland, Sch Accounting Econ & Finance, Toowoomba, Qld 4350, Australia
[2] Univ Penn, Ctr Populat Studies, Philadelphia, PA 19104 USA
[3] Human Sci Res Council, HIV AIDS STIs & TB HAST Res Programme, ZA-0001 Pretoria, South Africa
[4] Univ KwaZulu Natal, Hlth Econ & HIV AIDS Res Div HEARD, ZA-4041 Durban, South Africa
[5] Univ KwaZulu Natal, Dept Psychol, Howard Coll, ZA-4041 Durban, South Africa
[6] Univ Penn, Wharton Sch, Hlth Care Syst Dept, Philadelphia, PA 19104 USA