Short communicationMortality among injecting drug users in Melbourne: A 16-year follow-up of the Victorian Injecting Cohort Study (VICS)
Introduction
Injecting drug users (IDU) are at considerably greater risk of morbidity and mortality than their non-injecting peers (Warner-Smith et al., 2001). Characteristics such as gender and age (Hickman et al., 2003), psychosocial factors such as unemployment and imprisonment (Brugal et al., 2005), dose and frequency of injection (van Ameijden et al., 1999), medical complications from injecting drugs (Warner-Smith et al., 2001), and healthcare and drug treatment utilisation (Langendam et al., 2001) are important factors determining mortality risk among IDU. Risk may also be affected by structural and environmental characteristics related to drug policy environments (Burris et al., 2004, Kerr et al., 2007).
Few studies of mortality among IDU cohorts have been conducted in Australia, with most research focused on coronial data. While these studies are important, they cannot determine IDU mortality rates as the size of the population at risk is unknown. Given the complexity of the factors described above and variations in the characteristics of IDU and drug using environments internationally, we would expect to see differences in rates of mortality between jurisdictions. Indeed, substantial variations in mortality rates have been reported between countries and over time (EMCDDA, 1999). For this reason it is important to understand IDU mortality in Australia, where harm minimisation is the overarching drug policy (Ritter et al., 2004).
We retrospectively examined mortality within the Victorian Injecting Drug Users Cohort Study (VICS) of Australian IDU recruited in the early 1990s. Our aim was to provide IDU mortality data comparable to those reported internationally and examine characteristics associated with mortality in an Australian context.
Section snippets
VICS
VICS was the first longitudinal study of IDU conducted in Australia. A detailed description of VICS is reported elsewhere (Crofts and Aitken, 1997). Briefly, VICS was a longitudinal study of 626 IDU recruited through the social networks of ‘privileged access’ interviewers (PAIs; former or continuing IDU with extensive experience of the IDU “scene”) and ‘snowballing’ from these networks. VICS PAIs interviewed participants at approximately nine-month intervals between 1990 and 1995, recording
Results
In assessing selection bias, there were few statistically significant differences between the mortality cohort and the remainder of the VICS participants, except that the mortality cohort was more likely to have drug treatment experience and less likely to report government benefits as their primary income source (neither of which were associated with mortality in the mortality cohort). Characteristics of the mortality cohort sample were generally similar to those of other samples of IDU
Discussion
Overall and overdose mortality rates in this cohort were lower than those reported in Europe and the USA, where overall mortality among IDU over comparable years range largely between 1–5 per 100 PY, but were typically in the order of 3 per 100 PY (e.g. EMCDDA, 1999, Langendam et al., 2001, Vlahov et al., 2004). A few previous Australian studies also show relatively low mortality rates. A follow-up of methadone patients (1976–1991) produced an overall mortality rate of 1.12 per 100 PY and an
Conflicts of interest
The authors have no conflicts of interest to declare in relation to this study.
Acknowledgements
The authors would like to acknowledge John Harding, Mark Short and Kun Zhao from the Australian Institute of Health and Welfare for their advice and assistance in facilitating the data linkage component of this study, Jenny Kelsall and Michael Kerger who collected the original VICS data used in this paper and who kindly extracted participant identifying information, and finally Eulalio Ledesma for his advice in the preparation of this manuscript. We would also like to thank Turning Point
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