Drug and Alcohol Dependence 87 (2007) 39–45
Predictors of non-fatal overdose among a cohort of
polysubstance-using injection drug users
, Nadia Fairbairn
, Mark Tyndall
, David Marsh
, Julio Montaner
British Columbia Centre for Excellence in HIV/AIDS, St. Paul’s Hospital, 608–1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6
Department of Medicine, University of British Columbia, 608–1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6
Vancouver Coastal Health, 200–520 West 6th Avenue, Vancouver, BC, Canada V5Z 4H5
Received 12 November 2005; received in revised form 20 July 2006; accepted 23 July 2006
Background: Non-fatal overdose is a major determinant of morbidity among injection drug users (IDU). We sought to evaluate factors associated
with non-fatal overdose among IDU in Vancouver.
Methods: We examined non-fatal overdose among participants in the Vancouver Injection Drug Users Study. Correlates of non-fatal overdose
occurring between 1996 and 2004 were identiﬁed using generalized estimating equations (GEE).
Results: There were 1587 participants included in this analysis, including 576 (36%) women. At baseline, 750 (47%) reported a history of non-fatal
overdose. In total, 985 reports of non-fatal overdose were made during follow-up by 519 (32.7%) participants. In multivariate GEE analyses, factors
independently associated with non-fatal overdose included: heroin injection (AOR = 2.67), cocaine injection (AOR = 2.01), benzodiazepine use
(AOR = 2.00), requiring help injecting (AOR = 1.58), binge drug use (AOR = 1.52), homelessness (AOR = 1.38), alcohol use (AOR = 1.32), street
injecting (AOR = 1.22), non-injectable opiate use (AOR = 1.16), speedball use (AOR = 1.15), and recent incarceration (AOR = 1.14). Younger age
(AOR = 0.99) and methadone use (AOR = 0.51) were protective.
Conclusions: We found that non-fatal overdose was common among local IDU. Non-fatal overdose was associated with several factors that may
be amenable to intervention, including opiate and stimulant use, and the characteristic of requiring help with injecting. These ﬁndings indicate the
need for the ongoing development of structural interventions to address this common cause of morbidity among IDU.
© 2006 Elsevier Ireland Ltd. All rights reserved.
Keywords: Non-fatal overdose; Injection drug users
Illicit drug-related overdose has been recognized as a major
determinant of morbidity and mortality among injection drug
users (IDU) (Wood et al., 2003; Davidson et al., 2003; Warner-
Smith et al., 2002). In many countries, fatal overdose is a leading
cause of death among IDU, and in response a variety of overdose
prevention initiatives have been implemented (Tyndall et al.,
2001; Perucci et al., 1991).
Despite being far more common than fatal overdose, non-fatal
overdose has received considerably less attention in the scien-
tiﬁc literature (Darke et al., 2003). Among IDU participating in
Corresponding author. Tel.: +1 604 806 9116; fax: +1 604 806 9044.
E-mail address: firstname.lastname@example.org (T. Kerr).
studies in Australia and the UK, approximately 30% reported
having experienced a non-fatal overdose in the preceding 12
months, and 17% of opiate users in a recent Canadian study
reported a non-fatal overdose in the previous 6 months (Bennett
and Higgins, 1999; Warner-Smith et al., 2002; Fischer et al.,
2004). Non-fatal overdose is an important cause of morbidity
among IDU and can result in a number of medical compli-
cations, including aspiration pneumonia, hypoxic brain injury,
rhabdomyolysis, and renal failure (Darke and Hall, 2003).
Previous studies of non-fatal overdose have typically focused
on opiate users, with few studies examining non-fatal overdose
related to cocaine use (Kaye and Darke, 2004). Studies of non-
fatal overdose where polysubstance-use is prevalent are lacking,
as are longitudinal analyses of non-fatal overdose (Darke and
Hall, 2003). Further, while fatal overdose has been identiﬁed as
a leading cause of death among IDU in Vancouver (Tyndall et
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