drug users in amsterdam: are they still at risk for hiv? nienke van der knaap, bart grady, maarten...

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

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

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

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

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

Abstract #: A-452-0147-08988

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

Abstract #: A-452-0147-08988

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

Abstract #: A-452-0147-08988

HIV incidence

Abstract #: A-452-0147-08988

Injecting and sexual risk behaviour

Abstract #: A-452-0147-08988

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%)

Abstract #: A-452-0147-08988

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

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

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