Download files
Abstract
The Australian Needle and Syringe Program Survey (ANSPS) is a well-established sentinel surveillance tool that provides serial point antibody prevalence estimates of HIV and hepatitis C virus (HCV) antibody and associated risk behaviour among people who inject drugs (PWID). This thesis presents three studies that developed methodologies to enhance the existing ANSPS in order to investigate important epidemiological aspects of HCV infection.
The extent of syringe ‘coverage’ required to prevent or reduce HCV transmission among PWID remains a key question with little high quality data informing this issue. Although Australia has achieved and maintained a low rate of HIV prevalence among PWID, the early and widespread establishment of needle and syringe programs has not been sufficient to prevent transmission of HCV among this group. The first study examined individual-level syringe coverage among a national sample of n=1,568 PWID, identifying high levels of syringe coverage by international standards.
The second study used a simple deterministic linkage method to create a passive retrospective cohort of HCV antibody negative ANSPS respondents to examine HCV incidence over the period 1996 to 2010. The study demonstrated a significant decline in HCV incidence during a period of considerable change in drug markets, substantial expansion of harm reduction programs and a probable reduction in the size of the Australian PWID population.
Given high prevalence of HCV among Australian PWID and an expanding burden of liver-related morbidity, the third study investigated temporal trends and predictors of HCV treatment uptake among this population. The results indicated that although lifetime treatment uptake increased significantly between 1999 and 2011, annual treatment uptake remained low.
Together these studies demonstrate the additional capacity of sentinel surveillance to monitor and evaluate the effectiveness of HCV prevention and treatment interventions. Data on treatment uptake and outcomes will become increasingly valuable with the rollout of new interferon-free direct acting antiviral regimens that are likely to replace existing HCV therapy over the next 2-5 years. Future opportunities include estimation of the proportion of incident and chronic infections using recently conducted RNA serology; and investigation of the feasibility of phylogenetic analysis to examine genotype distribution and mixed infection.