RISK FACTORS FOR ELEVATED HIV INCIDENCE AMONG ABORIGINAL INJECTION DRUG
USERS IN VANCOUVER

From the British Columbia Centre for Excellence in HIV/AIDS, St. Paul's
Hospital (all authors), and the Departments of Health Care and Epidemiology
(Craib, Spittal, Wood, Hogg, Heath, Tyndall and Schechter) and of Pathology
and Laboratory Medicine (O'Shaughnessy), University of British Columbia,
Vancouver, BC.

Correspondence to: Dr. Patricia Spittal, BC Centre for Excellence in
HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard St., Vancouver BC V6Z 1Y6;
fax 604 806-9044; pspittal@hivnet.ubc.ca

Abstract

Background: Because of established links between entrenched poverty and
risk of HIV infection, there have long been warnings that HIV/AIDS will
disproportionately affect Aboriginal people in Canada. We compared HIV
incidence rates among Aboriginal and non-Aboriginal injection drug users
(IDUs) in Vancouver and studied factors associated with HIV seroconversion
among Aboriginal participants.

Methods: This analysis was based on 941 participants (230 Aboriginal
people) recruited between May 1996 and December 2000 who were seronegative
at enrolment and had completed at least one follow-up visit. Incidence
rates were calculated using the Kaplan-Meier method. The Cox proportional
hazards regression model was used to identify independent predictors of
time to HIV seroconversion among female and male Aboriginal IDUs.

Results: As of May 31, 2001, seroconversion had occurred in 112 (11.9%) of
the participants, yielding a cumulative incidence of HIV infection at 42
months of 12.7% (95% confidence interval [CI] 10.3%-15.1%). The cumulative
incidence at 42 months was significantly higher among the Aboriginal
participants than among the non-Aboriginal participants (21.1% v. 10.7%, p
( 0.001). This elevation in risk was present in both female and male
Aboriginal IDUs. Among the female Aboriginal IDUs, frequent speedball
(combined cocaine and heroin) injection (adjusted relative risk [RR] 3.1;
95% CI 1.4-7.1) and going on binges of injection drug use (adjusted RR 2.3;
95% CI 1.0-5.2) were found to be independent predictors of HIV
seroconversion. Among the male Aboriginal IDUs, the independent predictors
of seroconversion were frequent speedball injection (adjusted RR 2.9; 95%
CI 1.0-8.5) and frequent cocaine injection (adjusted RR 2.5; 95% CI 1.0-6.5).

Interpretation: In Vancouver, Aboriginal IDUs are becoming HIV positive at
twice the rate of non-Aboriginal IDUs. Our findings emphasize the urgent
need for an appropriate and effective public health strategy -- planned and
implemented in partnership with Aboriginal AIDS service organizations and
the Aboriginal community -- to reduce the harms of injection drug use in
this population.

Little is known about the extent of the HIV epidemic among Aboriginal
people in North America., The reasons for this include limited HIV/AIDS
surveillance data, underreporting, and inconsistent documentation of ethnic
status between provinces. However, because of the established links between
entrenched poverty and risk of HIV infection, there have long been warnings
that HIV/AIDS will increasingly affect Aboriginal people in Canada.,,
Regrettably, with the few data available, alarming trends have already
emerged. In 1990 an estimated 1% of all reported AIDS cases involved
Aboriginal people; by 1999 this proportion had increased to 10.8%. Despite
constituting only about 2.8% of the general population, Aboriginal people
accounted for about 9% of all people with newly diagnosed HIV infection in
1999. Indeed, from 1996 to 1999 the estimated number of Aboriginal people
with HIV infection rose from 1430 to 2740.

In addition, there are some data to suggest that HIV/ AIDS among Aboriginal
people is disproportionately affecting youth and women. In provinces with
reported ethnicity data, 33% of Aboriginal people with HIV infection newly
diagnosed between 1988 and 2000 were less than 30 years old, as compared
with 20% of non-Aboriginal people with newly diagnosed HIV infection; a
similar difference was observed in cases involving women (47% v. 20%). With
the exception of national statistics indicating that injection drug use
accounted for the majority (60%) of new infections among Aboriginal people
between 1998 and 2000, risk factors that explain elevated risk and
transmission of HIV among Aboriginal people are not well understood.

We have been following a cohort of more than 1400 injection drug users
(IDUs) in Vancouver since 1996, of whom about 25% are Aboriginal people. At
enrolment, HIV prevalence rates among Aboriginal IDUs were higher than
their non-Aboriginal counterparts (31% v. 18%; p ( 0.001). Follow-up of the
cohort now allows for an investigation aimed at comparing HIV incidence
among Aboriginal and non-aboriginal IDUs and identifying predictors of HIV
seroconversion among Aboriginal women and men in the study.

Methods

The Vancouver Injection Drug User Study (VIDUS) is a prospective study
involving 1437 people who were recruited through self-referral and street
outreach from Vancouver's Downtown Eastside between May 1996 and December
2000. Individuals were eligible if they were 14 years of age or older, had
injected illicit drugs at least once during the month before enrolment,
resided in the greater Vancouver region and provided written informed
consent. Participants were given a stipend (Can$20) at each study visit to
compensate them for their time and to facilitate transportation. The study
was approved by the University of British Columbia/Providence Healthcare
Research Ethics Board.

At enrolment and semi-annually, participants completed an
interviewer-administered questionnaire to elicit sociodemographic data and
data on injection and non-injection drug use, injection practices and
sexual risk behaviours. At each visit venous blood samples were drawn and
tested for HIV and hepatitis C virus antibodies. All eligible participants
had private interviews and pre- and post-test counselling with trained
nurses; referral for HIV/ AIDS care was provided to those found to be HIV
positive. Aboriginal status was based on self-report by individuals as
Metis, Aboriginal or First Nations.

Wood E, Tyndall MW, Spittal PM, Li K, Kerr T, Hogg RS, Montaner JS, et al .
Unsafe injection practices in a cohort of injection drug users in
Vancouver: Could safer injection rooms help? CMAJ
2001;165(4):405-10.[Abstract/Free Full Text]

Population by Aboriginal groups and sex, showing age groups for provinces
and territories. Ottawa: Statistics Canada; 1996. Cat no 93 F0025XDB96002.

Joining the circle: an Aboriginal harm reduction model. Ottawa: Canadian
Aboriginal AIDS Network; 1999. Available (PDF format):
www.caan.ca/Eoldpub.htm#hrm (accessed 2002 Nov 28).

BC Aboriginal HIV/AIDS Task Force. The red road: pathways to wholeness. An
Aboriginal strategy for HIV and AIDS in BC. Vancouver: The Task Force;
1999. Available (PDF format):
www.healthservices.gov.bc.ca/cpa/publications/red-road.pdf (accessed 2002
Nov 25).

Strathdee SA, Galai N, Safaiean M, Celentano DD, Vlahov D Johnson L, et al.
Sex differences in risk factors for HIV seroconversion among injection drug
users: a 10-year perspective. Arch Intern Med 2001;161(10):1281-8.[Medline]

Kral AH, Bluthenthal RN, Lorvick J, Gee L, Bacchetti P, Edlin BR. Sexual
transmission of HIV-1 among injection drug users in San Francisco, USA:
risk-factor analysis. Lancet 2001;357(9266):1397-401.[Medline]

Wyatt GE, Myers HF, Williams JK, Kitchen CR, Loeb T, Carmona JV, et al.
Does a history of trauma contribute to HIV risk for women of color?
Implications for prevention. Am J Public Health
2002;92(4):660-6.[Abstract/Free Full Text]

Oscapella E. How Canadian laws and policies on "illegal" drugs contribute
to the spread of HIV infection and hepatitis B and C. Ottawa: Canadian
Foundation for Drug Policy; 1995. Available: www.cfdp.ca/aidsd95.html
(accessed 2002 Nov 20).

Wood E, Tyndall MW, Spittal PM, Li K, Hogg RS, Montaner JS, et al. Factors
associated with persistent high-risk syringe sharing in the presence of an
established needle exchange programme. Aids 2002;16(6):941-3.[Medline]

Miller CL, Chan KJ, Palepu A, Tyndall MW, Hogg RS, O'Shaughnessy MV.
Socio-Demographic profile and HIV and hepatitis C prevalence among persons
who died of a drug overdose. Addict Res Theory 2001;9(5):459-70.

Ochoa K, Hahn JA, Seal KH, Moss AR. Overdosing among young injection drug
users in San Francisco. Addict Behav 2001;26(3):453-60.[Medline]

Broadhead RS, Kerr TH, Grund JP, Altice FL. Safer injection facilities in
North America: their place in public policy and health initiatives. J Drug
Issues 2002;32(1):329-55.

Perneger TV, Giner F, del Rio M, Mino A. Randomised trial of heroin
maintenance programme for addicts who fail in conventional drug treatments.
BMJ 1998;317(7150):13-8.[Abstract/Free Full Text]

Anderson JF. Holding the lid on HIV [editorial]. Can J Public Health 1999;
90(5):296-8.[Medline]

Gibson DR, Flynn NM, McCarthy JJ. Effectiveness of methadone treatment in
reducing HIV risk behavior and HIV seroconversion among injecting drug
users [editorial]. Aids 1999;13(14):1807-18.[Medline]

Tyndall MW, Craib KJ, Currie S, Li K, O'Shaughnessy MV, Schechter MT.
Impact of HIV infection on mortality in a cohort of injection drug users. J
Acquir Immune Defic Syndr 2001;28(4):351-7.[Medline]

O'Neil JD, Reading JR, Leader A. Changing the relations of surveillance:
the development of a discourse of resistance in Aboriginal epidemiology.
Hum Organ 1998;57(2):230-7.

Population census of Canada. Ottawa: Statistics Canada; 1996.