HIV/AIDS Among Injecting Drug Users in Canada

HIV/AIDS Epi Updates

April 2003

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HIV/AIDS Among Injecting Drug Users in Canada

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In the early 1980s, the Canadian HIV epidemic was concentrated among men who have sex with men (MSM). By the early-to-mid 1990s, there was a change toward increasing transmission among injecting drug users (IDU) such that in 1996, approximately 47% or 1,970 of the estimated 4,200 new HIV infections that occurred in Canada that year were among IDU.¹ The national HIV estimates for 1999 show a slight drop in the number of new infections among IDU (1,430 of a total of 4,190 or 34%).² A similar trend occurred in the number of positive HIV test reports among adults reported to the Centre for Infectious Disease Prevention and Control (CIDPC). In 1996, 33.7% of positive HIV test reports were attributed to IDU and 28.7% in 1999.³ This Epi Update presents information on the status of HIV/AIDS among IDU in Canada.

AIDS Surveillance Data

Injecting Drug Use Remains a Significant Exposure Category among AIDS Cases

As of June 30, 2002, 18,336 cumulative AIDS cases had been reported to the Centre for Infectious Disease Prevention and Control (CIDPC).³ Of the 17,471 cumulative adult AIDS cases with known exposure category information, 6.9% (1,214) were attributed to injecting drug use and 4.6% (812) to men who have sex with men who are also IDU (MSM/IDU).

After steadily increasing to a peak of just over 21% in 1998-2000, the proportion of adult AIDS cases attributed to injecting drug use decreased to 14.1% in 2001. (Figure 1) In the first half of 2002, this proportion has risen to 23.9%, a level similar to those reported pre-2001. We will be monitoring this trend to see if it is sustained when data for the full year are available.

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Of the 1,214 adult AIDS cases attributed to injecting drug use as of June 30, 2002, 74% were males and 26% were females. The proportion of adult male AIDS cases attributed to IDU steadily increased from 3.4% in 1991 to a peak of 19.3% in 2000. This proportion decreased to 15.7% in 2001 and in the first half of 2002 has increased to 18.2%.

The proportion of adult female AIDS cases attributed to injecting drug use increased steadily from 19.4% in 1991 to a peak of 46.1% in 1998. While in 2001, this proportion dropped to 7%, in the first half of 2002, it has increased to reach 45.5%. It should be noted that these proportions are based on a relatively small number of cases.

HIV Surveillance Data

Proportion of HIV Positive Test Reports among IDU continues gradual decline

While AIDS data provide information on HIV infections that occurred about ten years in the past, HIV data provide a picture of more recent infections.

As of June 30, 2002, of the 25,530 cumulative positive HIV tests reported among adults to CIDPC since 1985 with exposure category information, 16.4% were attributable to injecting drug use. An additional 2.3% were attributed to the combined category of MSM who also inject drugs.³

Figure 2 shows the proportion of adult positive HIV tests attributed to injecting drug use to the end of 2001. Prior to 1996, the proportion was 10.7%. This proportion increased substantially to 29.5% in 1995 and peaked at just over 33% in 1996 and 1997. Since 1997, this proportion has gradually declined to 25.1% in 2001and this trend has continued in the first half of 2002 when it decreased to 23.3%.³

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The proportion of IDU among adult female positive HIV test reports peaked at 47.9% in 1999, declined to 32.6% in 2001and rose slightly to 35.5% in the first half of 2002. The corresponding figures among adult male test reports remained stable at just over 22% in 2000/2001 and decreased slightly to 19.8% in the first half of 2002.³

Among positive HIV test reports attributed to IDU up to June 30, 2002 with age information, the highest proportion remained among those aged 30-39 years (42.3%).³

HIV Incidence and Prevalence Remain unacceptably High among IDU

The SurvUDI study has been ongoing since 1995 and consists of centres providing needle exchange services to IDU in the province of Quebec, and Ottawa, Ontario. Results indicate that HIV incidence among repeat service attendees in the network were 4. 3 per 100 person-years in 1997, 4.0 in 1998, 3.4 in 1999, 3.9 in 2000 and 3.3 in 2001.⁴ Overall incidence from 1995 to August 31, 2002 was 3.0 per 100 person-years in Quebec City, 4.7 in Montreal, 5.1 in Ottawa/Hull and 3.9 for the overall SurvUDI network.⁵

The POLARIS study investigates HIV incidence according to risk category among repeat testers in Ontario's diagnostic HIV-testing database during the period 1992-2000. HIV incidence among IDU decreased from 0.64 per 100 person-years in 1992 to 0.14 per 100 person-years in 2000.⁶

Results from the Vancouver Injection Drug Use Study (VIDUS) showed that HIV incidence was 1.5 per 100 person-years in 2000, down from 10.3 in 1997 and 3.2 in 1999.⁷

Results from the Winnipeg Injection Drug Epidemiology (WIDE) study suggest that the prevalence of HIV infection among IDU in that city increased from 2.3% in 1986-90 to 12.6% in 1998.⁸

A 1999 seroprevalence survey among 159 IDU using the needle exchange program (NEP) in Victoria, B.C., showed that 21% were HIV-positive. This was significantly higher than the prevalence of about 6% found in a small study of NEP attendees in the same city in the early 1990s.⁹

Research conducted by Calgary's Needle Exchange Program, Safeworks, showed that the prevalence of HIV among IDU attending that city's NEP increased from 2.2% in 1992 to 3.3% in 1998.¹⁰

The Regina Seroprevalence Study conducted in 2000, estimated that HIV seroprevalence was 2.0% among self-identified IDU participants.¹¹ Results from the Prince Albert Seroprevalence and Risk Behaviour Survey (PASS) in 1998 suggested that HIV seroprevalence among self-identified IDU was 1.1%.¹²

Results from the SurvUDI study showed that overall HIV prevalence among study participants from 1995 to August 31, 2002 was 14.7%.⁵ In 2001, HIV prevalence was highest among urban IDU (19.7% in Ottawa/Hull, 19.1% in Montreal and 14.5% in Quebec City).⁴

Women, Youth and Aboriginal IDU Are Particularly at Risk for HIV Infection

Women

Since 1996, approximately one third to one half of new HIV test reports among women have been attributed to injecting drug use. The latest national HIV estimates published by CIDPC for 1999 indicate that an estimated 54% of all new HIV infections among women were attributed to IDU.²

Findings from the VIDUS study in Vancouver show that during the period May 1996 and December 2000, HIV incidence rates among female IDU in Vancouver were about 40% higher than those of male IDU.¹³

Youth

High HIV incidence rates were found among young IDU when the VIDUS study in Vancouver examined rates of HIV positivity among IDU participants who were 24 years of age and younger. HIV incidence rates in this age group were 2.96 for males and 5.69 for females per 100 person years,¹⁴ compared to an overall incidence rate of 1.5 per 100 person years in 2000.⁷

The HIV incidence among street youth in the Montreal Street Youth Cohort Study was 0.69 per 100 person years as of September 2000. Injecting drug use was the strongest predictor of seroconversion (becoming HIV positive).¹⁵

Results from Phase II of the Enhanced Surveillance of Canadian Street Youth Study conducted in 1999, showed that overall, 20% of participants (n=1,733) had ever injected drugs. There was considerable regional variation with 10% of participants in Halifax, to 30% of participants in Saskatoon, to 36% of participants in Vancouver reporting a history of injecting drug use.¹⁶

Aboriginal

Aboriginal persons are over-represented among IDU populations, and a larger proportion of Aboriginal HIV and AIDS cases are attributed to IDU than non-Aboriginal cases.¹⁷ The 1999 national HIV estimates indicate that 64% of all new HIV infections among Aboriginal people in 1999 were attributable to injecting drug use.²

An analysis comparing the seroconversion rates of Aboriginal IDU with non-Aboriginal IDU participating in VIDUS study in Vancouver found that Aboriginal IDU are seroconverting at twice the rate of non-Aboriginal IDU.¹⁸

International trends

A report published by UNAIDS and the WHO in December 2002, indicates that an estimated 42 million people in the world are living with HIV/AIDS, of whom 19.2 million are women and 3.2 million are children under 15 years of age. IDU is cited as one of the main modes of transmission for those living with HIV/AIDS in 7 of the 10 regions of the world and include North America, North Africa and Middle East, Western Europe and East Asia and Pacific. In Eastern Europe and Central Asia, where the epidemic began relatively later than in other regions (early 1990's), IDU is listed as the single main mode of transmission in that region.¹⁹Figure 3 shows the proportion of AIDS cases attributed to IDU in selected countries since 1995. While caution should be taken when comparing and interpreting data where surveillance systems may differ, it is interesting to note that while Canada is in the lower half of the graph, countries like Australia, Netherlands and UK have even lower proportions of reported AIDS cases attributed to IDU. While such ecological comparisons have their limitations, it may be related to the availability and acceptability of programs and services which advocate harm reduction within the IDU population in these countries. More research is needed to study the effectiveness of these programs and whether similar approaches could be applicable in the Canadian setting.

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Figure 3: Proportion of Reported AIDS cases attributed to IDU in selected countries by Year

*Sources
Australia: National Center in HIV Epidemiology and Clinical Research. HIV/AIDS viral hepatitis and sexually transmissible infection in Australia Annual Surveillance Report 2002. National Center in HIV Epidemiology and Clinical Research, The University of New South Wales, Sydney, NSW. 2002.www.med.unsw.edu.au/nchecr
Italy, Netherlands, Poland, Switzerland, Ukraine, UK: (1995-96)
European Center for the Epidemiological Monitoring of AIDS. HIV/AIDS surveillance in Europe: Report no. 61, 30 June 1999. www.eurohiv.org/AidsSurv/pdf/rap61.pdf
Italy, Netherlands, Poland, Switzerland, Ukraine, UK (1997-2001)
Iran, Thailand, US: UNAIDS/WHO. Epidemiological Fact Sheets on HIV/AIDS and Sexually Transmitted Infections. July 2002. www.unaids.org/hivaidsinfo/statistics/fact_sheets/index_en.htm
Canada: Health Canada. HIV and AIDS in Canada: Surveillance Report to June 30, 2002. Division of HIV/AIDS Epidemiology and Surveillance, Centre for Infectious Disease Prevention and Control, Health Canada, November 2002.

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Comment

A number of biases must be taken into account when interpreting the results noted above. HIV diagnostic data are limited to persons who present themselves for testing, and so trends in these numbers may be influenced by testing patterns or improved ability to remove duplicate tests. In addition, identifying information that accompanies HIV testing data is sometimes incomplete or inaccurate, and this may limit the usefulness of HIV data. Results of cohort studies are limited by selection biases, loss to follow-up, and problems with generalizability. Studies that have a cross-sectional design have their own respective limitations.

Despite these issues, available data show that the HIV epidemic among IDU in Canada continues to be a serious problem. HIV infection continues to spread in vulnerable populations and across geographic boundaries. Although the problem is best documented in larger cities, increasingly, it is now being seen outside major urban areas. Additional epidemiologic data are needed to better define the extent of the problem and to guide the development and refinement of effective prevention policies and programs. These data are especially needed for areas outside major urban areas and for Aboriginal populations, women and youth. Given the geographic mobility of IDU and their social and sexual interaction with non-users, the dual problem of injecting drug use and HIV infection is one that ultimately affects all of Canadian society.

References

1. Archibald CP, Remis RS, Farley J, Sutherland D. Estimating HIV prevalence and incidence at the national level: combining direct and indirect methods with Monte-Carlo simulation. XII International Conference on AIDS, Geneva, June-July 1998 (Abst. 43475).

2. Geduld J, Archibald CP. National trends of AIDS and HIV in Canada. CCDR 2000;26:193-201.

3. Health Canada. HIV and AIDS in Canada: surveillance report to June 30,2002. Division of HIV/AIDS Epidemiology and Surveillance, Centre for Infectious Disease Prevention and Control (CIDPC), Health Canada, November 2002.

4. Communication with R. Parent, Institut national de santé publique du Québec, Direction des risques biologiques, environnementaux et occupationnels, Infections transmissibles sexuellement ou par le sang (groupe ITSS), January 2003

5. Alary M, Hankins C. et Le Réseau SurvUDI. Surveillance épidémiologique de l'infection par le virus de l'immunodéficience humaine ches les utilisateurs de drogures par injection. Le Réseau SurvUDI. Rapport Intérimaire, Novembre 2002

6. Burchell A, Calzavara LM, Major C, Remis RS, Corey P, Myers T, Millson PE, Wallace E, and the Polaris Study Team. HIV Incidence among persons undergoing repeat diagnostic HIV testing in Ontario, 1992-2000. Can J Infect Dis 2002 13(Suppl A), 48A (Abstract 315)

7. Tyndall M, Johnston C, Craib K, Li K, Spittal P, O'Shaughnessy M, Schechter M. HIV Incidence and mortality among injection drug users in Vancouver - 1996-2000. Can J Infect 2001; 11 (Suppl B):69B 354P

8. Elliot LJ, Blanchard JF, Dinner KI, Dawood MR, Beaudoin C. The Winnipeg Injection Drug Epidemiology (WIDE) Study. Eighth Annual Canadian Conference on AIDS, Vancouver BC May 1-4 1999. Can J Infect Dis 1999;10 (suppl B):C314

9. Poffenroth L. RARE Project in Victoria. Proceedings of the Division of HIV/AIDS Epidemiology and Surveillance Annual Meeting, Halifax, November 16-18, 2000. Centre for Infectious Disease Prevention and Control, PHAC, Health Canada.

10. Guenter DC, Fonseca K, Nielsen DM, Wheeler VJ, Pim CP. HIV Prevalence remains low among Calgary's Needle Exchange Program Participants. Can. J Pub Hlth. 2000;91(2)129-132

11. Regina Health District, Saskatchewan Health, Division of HIV/AIDS Epidemiology and Surveillance, CIDPC, Health Canada. The Regina Seroprevalence Study: A Profile of Injection Drug Use in a Prairie City. 2000

12. Siushansian J, Hay K, Findlater R, Bangura H, Archibald C, Young E.. The Prince Albert seroprevalence study (PASS): prevalence of HIV, hepatitis B, and hepatitis C and high risk behaviours among injection drug users and their sexual partners. Report prepared for the Prince Albert Health District and Saskatchewan Health, Division of HIV/AIDS Epidemiology and Surveillance, CIDPC, 2001

13. Spittal PM, Craib KJP, Wood E, Laliberte N, Li K,Tyndall MW, O'Shaughnessy MV, Schechter MT. Risk factors for elevated HIV incidence rates among female injection drug users in Vancouver. CMAJ 2002, 166(7)894-899

14. Miller C, Tyndall M, Li K, Laliberte N, Spittal P, Schechter MT. High rates of HIV positivity among young injection users. Can J Infect Dis 2001 Vol 12 Suppl B: 340P

15. Roy E, Haley N, Leclerc P, Cédras L, Boivin JF. HIV Incidence in the Montreal Street Youth Cohort (MSYC). Can J Infect Dis 2002; 13(Suppl A):49A (Abstract 317)

16. Wong T. Enhanced surveillance of Canadian street youth. Proceedings of the MSM/IDU Data Consultation Meeting, Ottawa, March 8-9, 2001. Centre for Infectious Disease Prevention and Control, CIDPC, Health Canada.

17. Health Canada.?HIV/AIDS among Aboriginal Persons in Canada Remains a Pressing Issue?, HIV/AIDS Epi Update, Division o f HIV/AIDS Epidemiology and Surveillance, CIDPC, Health Canada, April 2003.

18. Craib KJP, Spittal PM, Wood E, Laliberte N, Hogg RS, Li K, Heath K, Tyndall MW , O'Shaughnessy MV, Schechter MT. Risk factors for elevated HIV incidence among Aboriginal injection drug users in Vancouver. CMAJ 2003;168(1)19-24

19. AIDS epidemic update, December 2002. Joint United Nations Programme on HIV/AIDS (UNAIDS) and World Health Organization (WHO) 2002

For more information please contact:

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Health Canada

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