Background: Little has been published on the effect of geography on methadone treatment outcomes.

Objective: To measure the effect of place on longitudinal outcomes

Methods: From 2003 to 2006, 215 clients were recruited to a cohort study of methadone treatment. Participants had their address and clinic geocoded. Treatment outcomes were measured at intake, at one and three years posttreatment using the Maudsley Addiction Profile instrument. Spider diagrams and buffer rings were used to visually map clinics and clients. Regression models were used to measure the effect of place.

Results: Client's accommodation and social and criminal problems in the region had a medium to large effect on heroin use. Analysis of buffer rings revealed that clients located within a 10-km radius of a major clinic demonstrated poorer outcomes in terms of heroin use.

Conclusion/Importance: Findings illustrated the relevance of geography on drug treatment outcomes and the planning of services.