Factors associated with geographic migration among a cohort of injection drug users.

We sought to determine factors associated with migration among injection drug users in Vancouver, Canada. We examined migration patterns among participants in the Vancouver Injection Drug Users Study. All participants were residents of Vancouver at the time of recruitment. Correlates of migration, defined as living outside of Greater Vancouver between June 1999 and May 2005, were identified using generalized estimating equations. Various factors were negatively associated with migration including frequent crack cocaine smoking (AOR = 0.44, 95% CI: 0.37-0.52), current methadone use (AOR = 0.50, 95% CI: 0.40-0.63), frequent heroin injection (AOR = 0.51, 95% CI: 0.41-0.64), requiring help injecting (AOR = 0.60, 95% CI: 0.47-0.77), sex trade involvement (AOR = 0.64, 95% CI: 0.51-0.82), living in unstable housing (AOR = 0.69, 95% CI: 0.58-0.83), public injecting (AOR = 0.75, 95% CI: 0.60-0.94), and incarceration (AOR = 0.77, 95% CI: 0.61-0.96). Alcohol use was positively associated with migration in this analysis (AOR = 1.25, 95% CI: 1.05-1.48). Our findings suggest that participants who migrated were less at risk for HIV infection, given lower levels of reported risk-taking.