Trends in the injection of midazolam and other drugs and needle sharing among injection drug users enrolled in the AIDSVAX B/E HIV-1 vaccine trial in Bangkok, Thailand

Midazolam injection may increase the hazards of drug use. Its ability to cause amnesia may be associated with increased HIV risk behaviour and its interaction with other licit and illicit drugs may cause overdose and death. We analysed midazolam injection among injecting drug users (IDUs) participating in the AIDSVAX B/E HIV-1 vaccine trial in Bangkok, Thailand. From March 1999 to August 2000, 2545 IDUs were enrolled and randomised to receive AIDSVAX B/E or placebo. An interviewer-administered questionnaire assessed demographics (at baseline) and drug use behaviour (every 6 months). Reports of midazolam injection were statistically evaluated. During 36 months of follow-up, injection of any drug decreased from 94 to 51% and needle sharing decreased from 33 to 16%. Among those who continued to inject, midazolam injection increased from 10 to 31% (all p < 0.0001). Earlier study visit, lower education and less frequent injection were independently associated with less frequent midazolam injection; younger age, reports of needle sharing and receiving methadone treatment were independently associated with more frequent midazolam injection. Preventive interventions to educate IDUs and midazolam prescribers are urgently needed.