Social Determinants Predict Needle Sharing Behaviour Among Injection Drug Users in Vancouver
To identify determinants of needle sharing behaviour in Vancouver, where a recent outbreak of HIV infection occurred among injection drug users (IDUs) despite longstanding needle exchange and outreach services.
A total of 281 IDUs participated in a case control study of risk factors for HIV infection. HIV+ subjects had a documented seroconversion in 1994 -1995 (N=89) and HIV-'ve subjects had two documented negative tests within the same period (N=192). Face-to-face interviews focused on the period between the two HIV tests (inter-test interval), and included questions on drug use, needle sharing, source of needles, sexual behaviours, migration, housing, incarceration, and depression (7 item CES-D). Subjects were also asked whether they had "ever been forced to have sex" before age 12, between 12-17 yrs or >18 yrs. Univariate and multivariate logistic regression models were used to identify determinants of borrowing used needles within the inter-test interval.
105 males and 49 females reported borrowing needles. Borrowers were more likely to: live married and common law (65% vs 51%, p=0.03), inject >4 X/day, (p<0.001), inject >1 drug (p<0.001), have sex with the same sex (17% vs 6%, p=0.007), report having been forced to have sex (67% vs 46%, p<0.001), have a CES-D score above the upper quartile (32% vs 18%, p=0.009), and test HIV+ at the end of the interval (38% vs 24%, p=0.008). Females were more likely than males to report forced sex (75% vs 27%, p<0.001), but males were more likely to report forced sex <12 yrs (p=0.08). At least 59% of these subjects experienced forced sex before first injecting drugs. In the final multivariate model, after adjusting for HIV serostatus [AOR=2.2, (95% CI: 1.2-4)], factors remaining independently associated with borrowing were: being male [AOR=3.1, (CI: 1.5-6.6)], living common law/married [AOR=2.4, (CI: 1.3-4.7)], injecting >4X/day [AOR=3.4, (CI: 1.9-6.1)], injecting >1 drug [AOR=4.1, (CI: 2.2-7.8)], ever being forced to have sex [AOR=2.9, (CI: 1.5-5.7)], a higher CES-D score [AOR=2.3, (CI: 1.2-4.7)] and having sex with the same sex (AOR=2.6, CI: 1.03-6.8). Access or barriers of clean needle use were not independently associated with borrowing used needles. Results were similar after stratifying by gender.
Factors suggestive of underlying psychological distress, rather than access to clean needles, were strongly associated with needle sharing, as indicated by a higher frequency of sexual abuse and depression among borrowers. Early identification of these factors should be a component of HIV prevention programs aimed at IDUs. Improved social support and coping skills could reduce the frequency of needle-sharing behaviours.
Dr. Steffanie A. Strathdee
BC Centre for Excellence in HIV/AIDS
611-1081 Burrard Street
St. Paul's Hospital
Vancouver, BC, V6Z 1Y6
Tel: (604) 631-5535, Fax: (604) 631-5464