Behaviour change and HIV infection in Montreal injection drug users

Objective. To investigate the independent association of changes in sexual and drug injection risk behaviour on Human Immunodeficiency Virus (HIV) seroconversion among Montreal injection drug users (IDUs).Design. Subjects were selected from the St. Luc cohort, a prospective study that has recruited IDUs since September 1988. Eligible subjects must have enrolled in the cohort after December 31, 1991 and completed at least two follow-up visits. HIV serostatus testing was performed at baseline and semi-annually. Questionnaires on injection and sexual risk behaviour were administered at each visit. Cox regression with time-dependent covariates was used in the analysis.Results. The risk of HIV infection appears to be dependent upon the consistency of risk behaviour practiced. Chronic IDUs, who made no attempt to change risk behaviour, were at high risk of HIV infection. Episodic IDUs, who attempted to practice low risk behaviour but experienced frequent relapse to high risk behaviour, were also at considerable risk of HIV infection. Episodic IDUs demonstrated a higher risk of HIV infection than chronic IDUs for certain behaviours. Stable IDUs, who had managed to maintain low risk behaviour, were at minimal risk of HIV infection.Conclusion. Despite widespread reported behaviour change among Montreal IDUs, a substantial amount of high risk sexual and injection behaviour continues. Programs should be developed to address IDUs in each stage of change: IDUs who have no desire to change their behaviours, IDUs who require assistance maintaining behaviour changes and IDUs who have adopted low risk practises and are approaching long term maintenance of behaviour change