Limits to Relying on Expert Information: The Delphi Technique in a Study of Ethnic Vietnamese Injection Drug Users in Melbourne, Australia

Information from experts, or a??a??key informants,a??a?? is often used when constructing prevalence estimates or costs of diseases such as HIV and hepatitis C virus (Archibald et al., 2001). Experts and key informants have contributed to the estimation of World Health Organization figures for the prevalence of HIV in many countries where the surveillance system is limited (World Health Organization, 2001). Such estimates rely on key informants through a Delphi process, and the report (p. 83) states that a??a??: : : estimates and projections [for HIV] : : : should only be used where there is no data available : : : a??a?? This is because such estimates may unduly influence public health responses to issues and ultimately lead policy decisions in the wrong direction. In Victoria, the second most populous state in Australia, there is concern surrounding the disproportionate number of ethnic Vietnamese injection drug users (IDUs) with newly diagnosed HIV infection (Hocking, Higgs, Keenan, Crofts, 2001). Although the numbers in global terms are small, there is apprehension about the potential for a sudden and significant increase in HIV infection in this group, as has been seen recently in Vietnam (Nguyen, Nguyen, Trinh, 2004), Russia (Gorbach, Ryan, Saphonn, Detels, 2002), and India (Panda et al., 2000). This concern was amplified by combined reports of ethnic Vietnamese IDUs traveling back to Vietnam (Elliott, Mijch, Street, Crofts, 2003; Kelsall, Higgs, Lam, Crofts, 1998; Vu, Higgs, Crofts, 2002) where, in some areas, the prevalence of HIV in IDUs is more than 50