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Drug users in Amsterdam: are they still at risk for HIV?
Nienke van der Knaap, Bart Grady, Maarten Schim van der Loeff, Titia Heijman, Arjen Speksnijder, Ronald Geskus, Maria Prins
Cluster of Infectious Diseases, Public Health Service Amsterdam
AIDS 2012, Washington
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Background
Drug users (DU) are at risk for contracting blood-borne viruses
Harm-reduction programmes contributed to stabilisation or
decline of HIV incidence (van den Berg 2007, Crawford 2010)
Between 1985 and 2005 we observed a decline in injecting risk
behaviour among DU in Amsterdam (Lindenburg et al. 2006)
However, sexual risk behaviour remained substantial and was
considered to be the main risk factor for HIV acquisition
Abstract #: A-452-0147-08988
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Objective
To examine whether drug users in Amsterdam
are still at risk for HIV
To assess whether there is a need for interventions to
reduce sexual risk behaviour.
Abstract #: A-452-0147-08988
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Methods (1)
The Amsterdam Cohort Studies among drug users
Open, ongoing cohort study since 1985
Visits every 4-6 months
Detailed questionnaires on self-reported sexual risk
behavior, (injecting) drug use and Sexual Transmitted
Infections (STI)
Blood is tested for HIV antibodies and collected for
storage
Abstract #: A-452-0147-08988
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Methods (2)
Trends in HIV incidence rate per calendaryear:– Person-time techniques
– Modelled using poisson regression
– Among all HIV negative DU at ACS entry
Trends in sexual and injecting risk behaviour – Modelled using logistic regression
– Adjusted for multiple visits per individual (GEE)
STI screening among all participants with a cohort visit
between November 2010 and June 2011.– Chlamydia trachomatis, Neisseria gonorrhoeae, Trepanoma pallidum
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Results
All visitors
N=1658
Gender, male (%) 1035 (62%)
Dutch Nationality 1183 (71%)
Age, median (IQR) 30 (26-35)
HIV Positive at study entry 322 (19%)
Unprotected sex, past 6 months 721 (44%)
Ever injected drugs 1158 (69%)
Injected drugs, past 6 months 868 (52%)
Alcohol (any daily), past 6 months 333 (20%)
Methadone prescription, past 6 months 636 (38%)
Baseline characteristics
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Results
Median follow-up time was 9.2 years (IQR 3.7-14.8)
Total follow-up time was 12,921 person-years
By December 2011, 464 participants had died
During a given calendar year about 93% (IQR 90-95)
returned for a follow-up visit the next year
97 participants seroconverted for HIV
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HIV incidence
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Injecting and sexual risk behaviour
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Recent visitorsAll visitors Recent visitors
N=1658 N = 197
Gender, male (%) 1035 (62%) 141 (72%)
Dutch Nationality 1183 (71%) 166 (84%)
Age, median (IQR) 30 (26-35) 49 (43-54)
HIV Positive at study entry 322 (19%) 15 (8%)
Unprotected sex, past 6 months 721 (44%) 72 (36%)
Ever injected drugs 1158 (69%) 124 (63%)
Injected drugs, past 6 months 868 (52%) 23 (12%)
Alcohol (any daily), past 6 months 333 (20%) 116 (59%)
Methadone prescription, past 6 months 636 (38%) 123 (62%)
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Multivariable
OR ( 95% CI) p-value
Partner type 0.001
Casual ref
Steady 3.77 (1.46-9.75)
Client 0.34 (0.07-1.63)
CSW 0.32 (0.10-1.05)
HIV status 0.002
HIV-negative ref
HIV-positive 0.07 (0.02-0.37)
Determinants of unprotected sex
CSW: Commercial Sex Worker
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Conclusions
Continuing very low HIV incidence rate
Injecting risk behavior and sexual risk behaviour are declining
over time.
Unprotected sex was still substantial in 2011, but mainly among
those having a steady partner and being HIV negative
STI prevalence was low
DU no longer play a role in the spread of HIV in Amsterdam
Abstract #: A-452-0147-08988
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Acknowledgements
All participants from the ACS among drug users
Evidence for harm reduction? A. de Vos– Session room 8, 17:30
Abstract #: A-452-0147-08988