title: Drug use and the risk of HIV infection amongst injection drug users participating in an HIV vaccine trial in Bangkok, 1999-2003.
abstract: BACKGROUND
  HIV spread rapidly amongst injecting drug users (IDUs) in Bangkok in the late 1980s. In recent years, changes in the drugs injected by IDUs have been observed. We examined data from an HIV vaccine trial conducted amongst IDUs in Bangkok during 1999-2003 to describe drug injection practices, drugs injected, and determine if drug use choices altered the risk of incident HIV infection.
  
  
  METHODS
  The AIDSVAX B/E HIV vaccine trial was a randomized, double-blind, placebo-controlled trial. At enrolment and every 6 months thereafter, HIV status and risk behaviour were assessed. A proportional hazards model was used to evaluate demographic characteristics, incarceration, drug injection practices, sexual activity, and drugs injected during follow-up as independent predictors of HIV infection.
  
  
  RESULTS
  The proportion of participants injecting drugs, sharing needles, and injecting daily declined from baseline to month 36. Amongst participants who injected, the proportion injecting heroin declined (98.6-91.9%), whilst the proportions injecting methamphetamine (16.2-19.6%) and midazolam (9.9-31.9%) increased. HIV incidence was highest amongst participants injecting methamphetamine, 7.1 (95% CI, 5.4-9.2) per 100 person years. Injecting heroin and injecting methamphetamine were independently associated with incident HIV infection.
  
  
  CONCLUSIONS
  Amongst AIDSVAX B/E vaccine trial participants who injected drugs during follow-up, the proportion injecting heroin declined whilst the proportion injecting methamphetamine, midazolam, or combinations of these drugs increased. Controlling for heroin use and other risk factors, participants injecting methamphetamine were more likely to become HIV-infected than participants not injecting methamphetamine. Additional HIV prevention tools are urgently needed including tools that address methamphetamine use.
authors.affiliation: Thailand Ministry of Public Health-U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand. Znd9@cdc.gov
authors.forename: Michael
authors.initials: M
authors.lastname: Martin
authors.forename: Suphak
authors.initials: S
authors.lastname: Vanichseni
authors.forename: Pravan
authors.initials: P
authors.lastname: Suntharasamai
authors.forename: Philip A
authors.initials: PA
authors.lastname: Mock
authors.forename: Frits
authors.initials: F
authors.lastname: van Griensven
authors.forename: Punnee
authors.initials: P
authors.lastname: Pitisuttithum
authors.forename: Jordan W
authors.initials: JW
authors.lastname: Tappero
authors.forename: Sithisat
authors.initials: S
authors.lastname: Chiamwongpaet
authors.forename: Udomsak
authors.initials: U
authors.lastname: Sangkum
authors.forename: Dwip
authors.initials: D
authors.lastname: Kitayaporn
authors.forename: Marc
authors.initials: M
authors.lastname: Gurwith
authors.forename: Kachit
authors.initials: K
authors.lastname: Choopanya
mesh_terms: D016915:AIDS Vaccines / Q000008:administration & dosage / Q000378:metabolism*; D000328:Adult; D001294:Attitude to Health; D004311:Double-Blind Method; D005260:Female; D006678:HIV; D015658:HIV Infections / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D006801:Humans; D008297:Male; D008875:Middle Aged; D009294:Narcotics; D010353:Patient Education as Topic; D012309:Risk-Taking; D012725:Sexual Behavior; D012747:Sexual Partners; D015819:Substance Abuse, Intravenous / Q000453:epidemiology / Q000523:psychology*; D013785:Thailand / Q000453:epidemiology; D055815:Young Adult
chemical_list: D016915:AIDS Vaccines; C112734:AIDSVAX; D009294:Narcotics