Background: The harsh living conditions of injecting drug users (IDUs) are associated with substantial morbidity. Despite the many steps taken to improve the health of IDUs, notably through harm reduction programs, most strategies have focused primarily on proximal risk factors, whereas distal determinants have been poorly addressed.

Objectives: This study identifies distal and proximal factors associated with recent episodes of illness among IDUs living in Montreal in 2005.

Methods: A cross-sectional survey was carried out between February and September 2005 in 666 IDUs 18 years old and over, living in Montreal, Quebec.

Results: The living conditions of IDUs illustrate their marginality: 70% are on social welfare, 38% beg for a living, 48% have a history of imprisonment, and 20% live on the street. Among the study sample, 176 subjects (26%) reported an episode of illness in the 6 months before the interview. Multiple regression analysis showed that the pathway from socio-demographic conditions to illness in IDUs is mediated by financial strain, marginality, risk behaviors and chronic health conditions. Eight distal factors were associated with episodes of illness in the last 6 months: female gender, older age, bisexual orientation, financial strain (begging on the street, receiving help from community centers), marginality (history of imprisonment or fine for criminal offenses, stealing, having no identity card), heroin injection, combined use of both cocaine and heroin, and sharing injection material. More proximally related factors were HIV infection, HCV infection and depression.

Conclusions: Current IDUs in Montreal live under difficult conditions which have serious health consequences. Efforts to improve their health should focus on changing these conditions.