Declines in HIV incidence and risk behaviours among drug users in Amsterdam

Drug Users in Amsterdam: Are They Still at Risk for HIV?

Nienke van der Knaap, Bart P. X. Grady, Maarten F. Schim van der Loeff, Titia Heijman, Arjen Speksnijder, Ronald Geskus, Maria Prins. PLoS One. 2013;8(3):e59125. doi: 10.1371/journal.pone.0059125. Epub 2013 Mar 18.

Background and Aims: To examine whether drug users (DU) in the Amsterdam Cohort Study (ACS) are still at risk for HIV, we studied trends in HIV incidence and injecting and sexual risk behaviour from 1986 to 2011.

Methods: The ACS is an open, prospective cohort study on HIV. Calendar time trends in HIV incidence were modelled using Poisson regression. Trends in risk behaviour were modelled via generalized estimating equations. In 2010, a screening for STI (chlamydia, gonorrhoea and syphilis) was performed. Determinants of unprotected sex were studied using logistic regression analysis.

Results: The HIV incidence among 1298 participants of the ACS with a total follow-up of 12,921 person-years (PY) declined from 6.0/100 PY (95% confidence interval [CI] 3.2–11.1) in 1986 to less than 1/100 PY from 1997 onwards. Both injection and sexual risk behaviour declined significantly over time. Out of 197 participants screened for STI in 2010–2011, median age 49 years (IQR 43–59), only 5 (2.5%) were diagnosed with an STI. In multivariable analysis, having a steady partner (aOR 4.1, 95% CI 1.6–10.5) was associated with unprotected sex. HIV-infected participants were less likely to report unprotected sex (aOR 0.07, 95% CI 0.02–0.37).

Conclusions: HIV incidence and injection risk behaviour declined from 1986 onwards. STI prevalence is low; unprotected sex is associated with steady partners and is less common among HIV-infected participants. These findings indicate a low transmission risk of HIV and STI, which suggests that DU do not play a significant role in the current spread of HIV in Amsterdam.

Abstract access [1]   

Editor’s notes: Drug users are at high risk of HIV, both from the risk of HIV arising from sharing injecting paraphernalia, along with HIV risks from sexual behaviour – including the increased risk of unprotected sex associated with the use of cocaine and other stimulants, or if drug users work as commercial sex workers. Earlier research showed a decline in injecting risk behaviour up to 2005, but a remaining risk of HIV transmission from sexual risk behaviour. This analysis shows that risk from injecting has continued to decline. The prevalence of unprotected sex was substantial, but mainly associated with having a steady partner, and was less common in HIV-infected participants. Taken together, the findings indicate a low transmission risk of HIV and STI in this population cohort, and suggest that drug use no longer plays a significant role in the spread of HIV in Amsterdam. This is in contrast to the increasing levels of HIV infection among drug users in other Eastern European settings, and underscores the importance of effective harm reduction programmes for drug users.  

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