HIV treatment outcomes among people who inject drugs in Victoria, Australia

BACKGROUND People who inject drugs (PWID) are a key population affected by HIV. We assessed the effectiveness of HIV treatment among a clinical cohort of people living with HIV (PLHIV) diagnosed and referred for community-based antiretroviral therapy (ART) in Victoria, Australia. METHODS HIV notification data from a central statewide registry were matched with HIV clinical data from two large HIV treatment centers in Melbourne. We used survival analysis and Cox proportional hazard models to estimate time to AIDS and death for PWID in HIV treatment, compared with non-injectors, in the period 1996-2008. RESULTS Of the 871 individuals, 93 (10.8%) had injecting as an exposure category and 671 (86%) had ever commenced ART. Adjusted analysis showed younger age, high initial CD4 cell count (>500 cells/mm(3)) or ever having a CD4 cell count >500/mm(3), and more recent calendar year of ART commencement were all associated with reduced hazards for AIDS and death, while older age, low initial CD4 cell count (<200/mm(3)), ever having a CD4 count <200/mm(3) (before or during treatment) and high initial viral load (>5 log10) were associated with increased risk of AIDS and death. PWID were no more likely to experience AIDS (HR 0.98 [0.54-1.80]) or death (HR 0.78 [0.18-3.42]) than non-injectors. CONCLUSION Survival of HIV-infected PWID on HIV treatment was equivalent to non-injectors. CD4 cell count, initial viral load, calendar year of commencing ART and age are more important determinants of AIDS and mortality than injecting status for in-treatment PLHIV in Victoria, Australia.