Recruitment, screening and characteristics of injection drug users participating in the AIDSVAX B/E HIV vaccine trial, Bangkok, Thailand

AIDS. 2004 Jan 23;18(2):311-6. doi: 10.1097/00002030-200401230-00022.


Objectives: To describe recruitment, screening and baseline characteristics of injection drug users (IDU) participating in a phase III HIV vaccine (AIDSVAX B/E; VaxGen, USA) trial and to compare enrollment characteristics between trial participants and 1209 IDU from a 1995-1998 vaccine trial preparatory cohort for changes that might impact trial design assumptions.

Methods: Enrollment for both studies was conducted at Bangkok narcotic treatment clinics, where a standardized questionnaire was administered on demographics, risk behavior and incarceration history over the previous 6 months.

Results: During 1999-2000, 4943 IDU were screened for enrollment; successful sources of recruitment included clinic attendees (43.4%), an IDU referral program (20.4%) and preparatory cohort participants (14.7%). Of those screened, 1689 (34%) were HIV seropositive (HIV subtype B 23.6%; subtype E 76.4%). Of the 2545 enrolled, 93.4% were male. Compared with cohort IDU, trial IDU were younger (mean age: 28.8 versus 31.3 years), better educated (secondary level or higher: 67.2% versus 58.7%), and less likely to inject drugs daily (39.4% versus 90.4%); they were more likely to have been incarcerated (78.4% versus 65.7%), have recently injected stimulants (14.8% versus 5.8%) and tranquilizers (11.5% versus 2.3%), and obtained needles/syringes from a source other than a pharmacist (7.2% versus 3.9%) (all P < or = 0.003).

Conclusions: IDU at high risk for HIV have been successfully enrolled in the AIDSVAX B/E efficacy trial. Only minor epidemiologic differences were found at enrollment between trial and preparatory cohort IDU. The latter has proven critical in guiding trial design; results are expected in late 2003.

Publication types

  • Clinical Trial
  • Clinical Trial, Phase III
  • Randomized Controlled Trial

MeSH terms

  • AIDS Vaccines*
  • Adult
  • Attitude to Health
  • Cohort Studies
  • Double-Blind Method
  • Female
  • HIV Infections / complications
  • HIV Infections / prevention & control*
  • HIV Seronegativity
  • HIV-1*
  • Humans
  • Male
  • Middle Aged
  • Patient Education as Topic
  • Patient Selection*
  • Risk-Taking
  • Sexual Partners
  • Substance Abuse, Intravenous / complications*
  • Surveys and Questionnaires
  • Thailand


  • AIDS Vaccines