Factors associated with willingness to participate in a heroin prescription program among injection drug users

Randomized controlled trials of prescription heroin have shown success in reducing drug-related harm among chronic opiate injection drug users (IDUs) in several European nations. We sought to explore willingness to participate in a heroin trial among a well-characterized North American cohort of IDUs, and therefore performed analyses of factors associated with willingness to participate in a prescription heroin trial among IDUs enrolled in the Vancouver Injecting Drug Users Study (VIDUS). Of 410 current heroin injectors followed between May and November 2002, injecting heroin frequently (more than once daily) [odds ratio (OR) 1.33; 95 percent confidence interval (CI) 1.06 to 1.69] and being enrolled in methadone maintenance therapy (MMT; OR 1.33, 95 percent CI 1.06 to 1.69) were associated with willingness to participate in a trial. In subanalyses, statistical associations with willingness to participate in a trial among current MMT users were frequent injection of heroin (OR 2.12, CI 1.16 to 3.88) and speedballs (OR 2.57, CI 1.02 to 6.48), frequent crack cocaine use (OR 1.84, CI 1.11 to 3.06), lending of syringes (OR 3.22, CI 1.08 to 9.65), and requiring help to inject (OR 1.83, CI 1.01 to 3.33). Among IDUs, willingness to enroll in a heroin prescription program was associated with high-intensity heroin injection and high-risk behaviors and was particularly prevalent among individuals who have been unable to significantly reduce their injection drug use on MMT alone. These findings indicate that a clinical trial of prescribed heroin should be able to enroll an appropriate sample of drug users and properly assess the treatment potential of prescribed opiate pharmacotherapy.