AEGiS-14IAC: The relationship between needle exchange intervention coverage and the HIV prevalence amongst intravenous drug users.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

The relationship between needle exchange intervention coverage and the HIV prevalence amongst intravenous drug users.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. MoOrD1062)

Vickerman PT, Watts C
London School of Hygiene and Tropical Medicine, London, United Kingdom

BACKGROUND: Needle exchange projects (NEPs) are effective in reducing HIV transmission amongst intravenous drug users (IDUs). However, there is little data on the required coverage and syringe exchange rate to result in a significant decrease in HIV transmission. We use a mathematical model to study this question for a NEP in Svetlogorsk, Belarus, where the IDU HIV prevalence is >70%. In 1999, the NEP reached 50% of IDUs and 35% of reached IDUs shared 120 syringes per year.

METHODS: A mathematical model was constructed to simulate the impact of a NEP intervention. The model assumes that the impact of the NEP on HIV transmission via needle sharing is dependent on the number of syringes exchanged per IDU and the number of IDUs reached by the NEP. Data from Svetlogorsk is used to validate the model and predict the impact on IDU HIV prevalence of increasing project coverage and achieving reductions in sharing behaviour.

RESULTS: The model simulations agree with the observed reduction in the IDU HIV prevalence in Svetlogorsk (74%-71% from 1997-2000). The model predicts that the current project activity achieved a 60% drop in HIV incidence. Sustained intervention activity would reduce IDU HIV prevalence below 60% by 2005 and 50% by 2017, plateauing at about 45%. The table shows the minimum IDU coverage requirements for the IDU HIV prevalence to decrease to 25% depending upon whether the intervention impact on IDU needle sharing either remains the same or increases.[table: see text]For the scenarios in the table, 27 years of sustained project activity are required to attain an IDU HIV prevalence of 25%. This reduces to ~14 years if the IDU coverage is increased by 10% above the minimum requirement.

CONCLUSIONS: NEPs can be successful in reducing HIV incidence and prevalence. However, significant drops in IDU HIV prevalence can only be achieved with sustained intervention activity (>10 years) that reaches the majority of IDUs and results in a large drop in needle sharing.

Keywords: AEGIS, Prevalence, Substance Abuse, Intravenous, Needle Sharing, HIV Infections, HIV Seropositivity, Incidence, Communicable Disease Control, Syringes, Byelarus, epidemiology

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MoOrD1062