The impact of blood-borne viruses on cause-specific mortality among opioid dependent people: An Australian population-based cohort study.
BACKGROUND
Blood-borne viruses (BBV) are prevalent among people with opioid dependence but their association with cause-specific mortality has not been examined at the population-level.


METHODS
We formed a population-based cohort of 29,571 opioid substitution therapy (OST) registrants in New South Wales, Australia, 1993-2007. We ascertained notifications of infection and death by record linkage between the Pharmaceutical Drugs of Addiction System (OST data), registers of hepatitis C (HCV), hepatitis B (HBV) and human immunodeficiency virus (HIV) diagnoses, and the National Death Index. We used competing risks regression to quantify associations between notification for BBV infection and causes of death. BBV status, age, year, OST status, and OST episodes were modelled as time-dependent covariates; sex was a fixed covariate.


RESULTS
OST registrants notified with HCV infection were more likely to die from accidental overdose (subdistribution hazard ratio, 95% Confidence Interval: 1.7, 1.5-2.0), cancer (2.0, 1.3-3.2) and unintentional injury (1.4, 1.0-2.0). HBV notification was associated with a higher hazard of mortality due to unintentional injury (2.1, 1.1-3.9), cancer (2.8, 1.5-5.5), and liver disease (2.1, 1.0-4.3). Liver-related mortality was higher among those notified with HIV only (11, 2.5-50), HCV only (5.9, 3.2-11) and both HIV and HCV (15, 3.2-66). Registrants with an HIV notification had a higher hazard of cardiovascular-related mortality (4.0, 1.6-9.9).


CONCLUSIONS
Among OST registrants, BBVs are a direct cause of death and also a marker of behaviours that can result in unintended death. Ongoing and enhanced BBV prevention strategies and treatment, together with targeted education strategies to reduce risk, are justified.
Adult Cancer Program, Lowy Cancer Research Centre, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: claire.vajdic@unsw.edu.au.
Claire M
CM
Vajdic
Sadaf
S
Marashi Pour
Adult Cancer Program, Lowy Cancer Research Centre, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW 2052, Australia; Centre for Epidemiology and Evidence, NSW Ministry of Health, Sydney, NSW 2059, Australia. Electronic address: sadaf.marashipour@health.nsw.gov.au.
Sadaf Marashi
SM
Pour
Adult Cancer Program, Lowy Cancer Research Centre, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW 2052, Australia; School of Mathematics and Statistics, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: j.olivier@unsw.edu.au.
Jake
J
Olivier
Adult Cancer Program, Lowy Cancer Research Centre, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: aswart89@gmail.com.
Alexander
A
Swart
Cancer Research Division, Cancer Council NSW, Sydney, NSW 2011, Australia; School of Medicine and Public Health, Faculty of Health, University of Newcastle, Callaghan, NSW 2308, Australia; School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia; Sydney Medical School - Public Health, University of Sydney, Sydney, NSW 2006, Australia. Electronic address: dianneo@nswcc.org.au.
Dianne L
DL
O'Connell
Adult Cancer Program, Lowy Cancer Research Centre, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: m.falster@unsw.edu.au.
Michael O
MO
Falster
Adult Cancer Program, Lowy Cancer Research Centre, Prince of Wales Clinical School, University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: nicki.meagher@unsw.edu.au.
Nicola S
NS
Meagher
Centre for Social Research in Health, Faculty of Arts and Social Sciences at the University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: limin.mao@unsw.edu.au.
Limin
L
Mao
Kirby Institute, Faculty of Medicine at the University of New South Wales, Sydney, Australia. Electronic address: agrulich@kirby.unsw.edu.au.
Andrew E
AE
Grulich
Centre for Health Research, University of Western Sydney, Sydney, NSW 2751, Australia. Electronic address: d.randall@uws.edu.au.
Deborah A
DA
Randall
Kirby Institute, Faculty of Medicine at the University of New South Wales, Sydney, Australia. Electronic address: jamin@kirby.unsw.edu.au.
Janaki
J
Amin
National Drug and Alcohol Research Centre, Faculty of Medicine at the University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: l.burns@unsw.edu.au.
Lucinda
L
Burns
National Drug and Alcohol Research Centre, Faculty of Medicine at the University of New South Wales, Sydney, NSW 2052, Australia; Centre for Health Policy, Programs and Economics, School of Population Health, University of Melbourne, Parkville, VIC 3010, Australia. Electronic address: l.degenhardt@unsw.edu.au.
Louisa
L
Degenhardt
D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D002423:Cause of Death; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000401:mortality*; D006509:Hepatitis B / Q000150:complications* / Q000401:mortality*; D006526:Hepatitis C / Q000150:complications* / Q000401:mortality*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D009293:Opioid-Related Disorders / Q000150:complications / Q000401:mortality* / Q000821:virology*; D015995:Prevalence; D012042:Registries; D055815:Young Adult
Blood-borne viruses; Mortality; Opioid dependence; Opioid substitution therapy; Pharmacotherapy