Introductory Editorial: the analysis of a natural experiment in HIV control

Almost every country in the developed world, including Australia, is experiencing significant and consistent rises in the rate of new HIV diagnoses among men who have sex with men (MSM).^1,2 This issue of Sexual Health describes and analyses the Australian data which is surprisingly different across Australia. New South Wales (NSW) has seen only an 8% increase in notifications among MSM (249 in 1999 and 270 in 2005), whereas Victoria has seen a 131% increase (78 in 1999 to 180 in 2005) and Queensland has seen a 55% increase (66 in 1999 to 102 in 2005, a 55% increase).¹

The objective of this issue is to provide the international audience with a thorough analysis of the potential reasons for the substantial differences in HIV notifications between states so that others may learn from the experience. Australia is in a fortunate situation of having several nationally funded HIV centres that collect national information. However, the policy response to the HIV epidemic is largely carried out by state and territory health departments, and this has led to substantial differences in HIV policies around Australia. In recent years, this divergence has been substantial, approximating a natural experiment in HIV prevention. In an international sense this provides a unique opportunity to analyse what works, at a policy level, in HIV prevention.

The first few papers present a detailed analysis of HIV notifications in different Australian states and then compare this with what is happening internationally.^2–6 Many of the subsequent papers deal with issues that may explain these differences. These include differences in:

• sexual practices and condom use

• the age distribution of those living with HIV infection

• the rates of sexually transmissible infections (STI) between states

• the testing rates for HIV and hence differential detection of HIV

• the access and provision of health care services to MSM

• the uptake of HIV treatment among MSM

• the use of primary HIV infection

• the use of suppressive herpes medication

• disclosure of HIV status and hence sero-sorting

• expenditure and investment in HIV prevention

As editors for this issue, we have taken the liberty of providing our view of what we consider is responsible for the differences in HIV notifications on the basis of the information that is available. We have then invited Dr Robert Griew to provide his opinion on what should be done.⁷ We trust you’ll enjoy this issue and hopefully find the thorough analysis of the issues useful in informing interventions to control HIV.