HIV/AIDS Epi Update - May 2004

Risk Behaviours Among Injecting Drug Users in Canada

Introduction

At A Glance

Available data indicate high levels of risky injecting and sexual behaviours among IDU, suggesting that the potential for the transmission of HIV in these populations continues to be significant.

Behavioural trend data are needed to reliably interpret changes in HIV incidence and prevalence among IDU, and to help evaluate prevention programs targeting this population.

Marked differences in the injecting drug use and HIV prevalence across different cities in Canada reflect the need to increase the geographic coverage of surveillance of risky behaviours among IDU.

The recently published national HIV prevalence and incidence estimates indicate that 30% or 800-1,600 of the estimated 2,800-5,200 new HIV infections that occurred in Canada in 2002 were among injecting drug users (IDU).1 Similarly, 34% of the estimated HIV infections that occurred in 1999 were among IDU.1 A similar trend has been observed in the number of positive HIV test reports attributed to injecting drug use reported to the Centre for Infectious Disease Prevention and Control (CIDPC). The proportion of adult positive HIV tests attributed to injecting drug use, after peaking at just over 33% in 1996 and 1997, has gradually decreased to 24.0% in 2002.²

Although these declining trends are encouraging, HIV among IDU remains a major concern. In the absence of a vaccine for HIV, behaviour change is the main tool for preventing HIV infection among drug injectors. Behaviour change concerns both IDU who are HIV-infected and those who are uninfected, and relates mainly to their injecting-related and sexual behaviour.

In response to a need for ongoing monitoring of HIV-associated risk behaviours in IDU populations, Health Canada, through collaboration with provincial, regional and local health authorities, community-based organizations and researchers, is establishing an HIV and hepatitis C (HCV)-associated risk behaviour enhanced surveillance system (I-Track) at sentinel centres across Canada. A pilot study of the I-Track surveillance system was undertaken between October 2002 and March 2003, when a total of 794 IDU were surveyed in Victoria, Regina, Sudbury and Toronto.3 In addition, linkages are also being made with the SurvUDI study in Quebec and Ottawa.

This Epi Update describes the drug injecting and sexual risk behaviours that have been reported by the I-Track pilot survey as well as by other studies of IDU in Canada.

Neither a Borrower Nor a Lender Be: The Sharing of Needles and Syringes

The sharing (borrowing and lending) of needles and syringes is well established as a means of transmitting HIV infection and is a common behaviour among IDU:

• Results of the I-Track pilot survey indicate that, overall, 24.5% of study participants reported injecting with used needles in the six months before the survey. Proportions ranged from 16.5% in Regina to 30.7% in Victoria. IDU borrow mostly from people with whom they inject, most often close friends/family or regular sex partners. Overall, a similar proportion reported passing on or lending needles/syringes (20.5%) to other IDU for injecting purposes in the preceding six month period. The range by site was 15.7% in Regina to 30.0% in Victoria.³
• A cohort study of IDU in Vancouver showed that 27.6% of the participants reported sharing needles in the previous six month period (administered during January 1999 to October 2000). Furthermore, 19.1% of the participants reported that they had shared even though they did not report having difficulty obtaining new, sterile needles.⁴
• Results from the SurvUDI study show that the prevalence of needle/syringe borrowing in the previous six months among first time needle exchange program (NEP) attendees in Montreal decreased from 45.1% in 1995 to 35.3% in 2002. In Quebec City, needle/syringe borrowing declined from 41.2% to 23.3% over the same period (although a slight increase was observed between 2001 and 2002). A decline in needle/syringe borrowing, from 31.8% in 1996 to 14.1% in 2002, was observed in Ottawa. While these results suggest that positive trends in the reduction of sharing behaviour among IDU may be occurring in these jurisdictions, the proportion of participants who report sharing needles is still relatively high.⁵

The borrowing and lending of other injecting equipment (e.g. spoons, filters and water), often referred to as "indirect sharing," have also been found to be associated with HIV infection. Research indicates that indirect sharing also occurs frequently among IDU:

• Of study participants in the I-Track pilot survey, 43.2% (range: 31.7% in Toronto to 53.5% in Regina) reported borrowing previously used other injecting equipment (filters, cookers, water) for injecting purposes in the preceding six months; 32.9% reported lending or passing on other injecting equipment in the six months prior to the survey.³
• In a 1998 study conducted in Calgary's needle exchange program (NEP), 25% of the participants reported that they had shared injecting equipment in the six months preceding the study.⁶
• In the VIDUS cohort study of IDU in Vancouver during 1996 to 2000, 38% of men and 37% of women reported borrowing injecting equipment, and it was found to be one of the risk factors for seroconversion among men.⁷
• International studies8-10 of IDU have identified other aspects of drug injecting, such as "front-loading" or "back-loading", which may also increase the risk of HIV transmission. These practices involve two or more IDU who use only one syringe to prepare a drug solution. The solution is then squirted into one or more additional syringes either via the front of the recipient syringe after removing its needle (front-loading) or via the back after removing the plunger (back-loading). However, the full extent of such risk behaviours among Canadian IDU is still under investigation.

Risky Business: Trading Unprotected Sex for Money and Drugs

Many IDU in Canada are involved in the commercial sex trade, and studies report inconsistent condom use with clients:

• Among IDU in the I-Track pilot survey, 39.5% of females reported engaging in commercial sex work in the six months before the survey. Condom use among female IDU during penetrative sex with client partners was generally high but was less so during oral sex: 5.7% reported never using a condom during oral sex and an additional 17.6% reported inconsistent condom use during oral sex.³
• Results from the SurvUDI study indicate that, between 1995 and 2003, 49.3% of females and 9.2% of males among repeat visit participants reported engaging in prostitution.⁵
• Among IDU recruited between 1988 and 1999 in a cohort study in Montreal, 18.1% of males reported that they had ever been a prostitute.¹¹
• In a 1998 study in Winnipeg, 71.5% of female IDU and 30.2% of male IDU reported that they had ever been paid for sex. Among females, 25.0% used condoms inconsistently with their sex trade clients. Among men with male clients, 52.0% reported inconsistent condom use.¹²
• In a 1998 study in Saskatoon, half of the female IDU population reported having been paid for sex and 19% having exchanged sex for drugs or a place to sleep in the preceding six months.13 In the same study, condom use with casual partners was reported by 93%, but one-quarter of those did not always use a condom. Overall, 41% of the study population used condoms with regular partners.

Not Safe Enough: Sex with Regular and Casual Partners

Among IDU with regular and casual opposite sex partners, condom use is low:

• Analysis of condom use among I-Track pilot survey participants indicates that reported condom use during penetrative and oral sex in the preceding six months was more infrequent with casual sex partners than with client sex partners, and more infrequent still with regular sex partners. This pattern of decreased condom use in more stable relationships was reported by both male and female IDU. Among males, 19.4% and 56.6% reported never using a condom during penetrative and oral sex respectively with their casual sex partners in the preceding six months. Among females, 28.4% and 34.0% reported never using a condom with casual sex partners during penetrative and oral sex respectively in the preceding six months. There were no marked differences in reported condom use between participating sites.³
• In the 1998 study of IDU in Winnipeg, 68.0% of women and 57.0% of men who had had regular partners in the previous year reported that they never used condoms. Of those who reported having had casual partners in this time period, approximately 30.0% of both men and women never used condoms.¹²
• Among IDU in the Regina seroprevalence study conducted in 2000, condom use with regular and casual partners was low. For example, 94% of male IDU and 92% of female IDU reported inconsistent or no condom use during vaginal sex with regular, opposite sex partners. Of those respondents who had casual partners, 58% of men and 71% of women reported inconsistent or no use of condoms with this type of partner.¹⁴
• In the VIDUS cohort study in Vancouver during 1996-2000, 18% of men and 20% of women reported the use of condoms with regular sex partners in the previous six months; non-use of condoms with a regular sex partner was the most significant risk factor for seroconversion among women.⁷

Male IDU and Same Sex Partners

The proportion of male IDU reporting sexual intercourse with same sex partners varies in different cities:

• In the I-Track pilot survey, among male IDU, 4.4% reported having had male sex partners in the preceding six months.³
• Among male IDU in the VIDUS study who reported having had sexual intercourse in the previous six months, 7.0% reported having had only same sex partners and 6.0% reported having had partners of both sexes in this time period.¹⁵
• In the SurvUDI study, 14.7% of repeat-visit male subjects reported same sex partners between 1995 and 2003.⁵
• In the 1998 Calgary NEP study, 7% of men and 12% of women IDU reported having had sex with the same sex partner in the six months preceding the study.⁶
• In the Omega cohort study of MSM in Montreal, 6% of the MSM reported injecting drugs, among whom 48% had borrowed used needles and 4% had exchanged sex for drugs.¹⁶

Protective Behaviour Changes or Higher Risk Practices Following Positive HIV Test?

More research is needed to determine whether IDU continue to engage in high-risk behaviours or modify their behaviours after receiving a positive HIV antibody test:

• Among IDU in a Quebec cohort study conducted between 1996 and 1999, 73.1% of HIV-positive drug injectors had stopped lending needles compared with 56.0% of their HIV-negative counterparts in the six months after their HIV serostatus result. However, 8.5% of HIV-positive IDU compared with 16.0% of their non-infected peers began lending needles to HIV-positive partners in this same period. In the same study, 62.2% of HIV-positive drug injectors had stopped borrowing needles compared with 58.6% of their HIV-negative counterparts in the six months following their HIV serostatus result. Of HIV-positive IDU, 16.7% compared with 19.5% of their non-infected peers began borrowing needles from HIV-positive partners in this same period.¹⁷
• The VIDUS study in Vancouver reported that 35.0% of subjects who were HIV-positive reported that they had borrowed needles before learning about their serostatus. In the months after their HIV positive test, only 21.0% of these subjects reported that they continued to borrow needles. Similarly, 37.0% of HIV-positive IDU reported needle lending before their positive HIV test, whereas only 21.0% of these subjects continued this practice after receiving their positive test results.¹⁸
• In a study of women in Montreal, the rate of condom use following a positive HIV test was low among IDU (19%) as compared with non-IDU of Haitian origin (30%) and non-IDU of Caucasian origin (62%).¹⁹

Injecting Drug Use Is a Problem Among Street Youth and Inmates

Appropriate and accessible HIV prevention programs for drug injecting, street-involved youth and inmates are clearly needed:

• Results for the I-Track pilot survey showed that the mean age of initiation of injecting drug use was 21.4 years in the study population, and 30% reported beginning to inject at the age of 16 years or younger.³
• Results from the Montreal street youth study of those aged 14 to 25 years, from 1995 to 2000, show that 47.2% of the study participants had ever injected drugs. Injecting drug use was found to be the strongest indicator of HIV sero-conversion.²⁰
• The New Montreal Street Youth Cohort study, a prospective cohort study of street youth aged 14 to 23 years conducted between July 2001 and August 2002, found that of the street youth who were IDU, 55.2% reported injecting with a previously used needle and 54.4% reported sharing of a cooker/spoon.²¹
• Among female inmates in a Quebec prison in 1994, 38.0% reported injecting drugs before they were incarcerated, and about half of these women had shared needles. Of those who reported drug injecting before going to prison, 11.0% admitted to injecting drugs during their incarceration, and most (80.0%) shared needles.²²
• Among male inmates in this same study, 26.0% reported that they had injected drugs before being incarcerated, and about half of these had shared needles. Of those who admitted to injecting drugs outside prison, 2.0% reported injecting drug use during their incarceration, and most (92.0%) shared needles.²²
• In the 2002 Student Drug Use Survey in New Brunswick, less than 1% of the grade 7, 9, 10 and 12 students surveyed had injected drugs in the year preceding the study period.²³

Comment

Although several ongoing regional studies in Canada collect risk behaviour data on IDU and a large number of one-time, cross-sectional surveys on risk-taking among IDU have been conducted, it is challenging, if not impossible, to compare levels of risk behaviours between data sets. In addition to disparities across study methodologies, different researchers have collected risk behaviour data using different questions or differently worded questions, different variable or concept definitions, different time frames for reported behaviours and different response categories. It is therefore difficult to use available IDU risk behaviour information to identify trends or to help evaluate the effectiveness of prevention programs and policies at more than the regional or local level.

In addition, although the national HIV estimates for 2002 show a slight decline in the number of new infections attributed to injecting drug use in that year, the relative lack of behavioural trend data hinder the reliable interpretation of this finding. The establishment of the I-Track Survey will permit the tracking of injecting and sexual risk behaviours over time, will provide important trend data that could be used to inform prevention program design and would help evaluate program effectiveness. Such behavioural data could also be used to interpret changes in HIV prevalence and incidence among IDU and would serve as an early warning system for HIV spread in this population. The high levels of risky injecting and sexual behaviours reported by IDU in sentinel sites across Canada suggest that the potential for the transmission of HIV in these populations continues to be significant. Behavioural surveillance of key subgroups of IDU, namely street-involved youth and inmates, is also needed to formulate an appropriate response to the evolving HIV epidemic among IDU in Canada.

References

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