After 50 years of international experience and 15 years of use in France, the positive impact of drug replacement treatments on the care of patients with opiates dependence is now well established. Even though there is a vast literature on the two existing treatments (methadone and high-dosage buprenorphine), few works have focused on patients who have changed replacement therapy during follow-up.

The aim of our study was to analyze the follow-up of substituted patients throughout an 11-year period. Patients were characterized by the type of treatment: methadone only, high-dosage buprenorphine only, or both treatments.

These groups of patients were studied depending on their characteristics at the beginning of the treatment (sociodemographic data, addictive behaviours, psychiatric assessment) and in terms of healthcare and follow-up regularity. We also tried to bring to light predictive factors of unstable follow-ups at the point of entry in healthcare.

891 patients were included in our results. Patients having had two substitution treatments initially present with higher severity in terms of socio-professional integration, addictive behaviours and psychiatric comorbidity. Their treatment is more discontinued and they have longer healthcare.

Psychiatric comorbidities and poly-drug use seem to characterize unstable patients who jeopardize our treatments. They have to be identified very early in order to better adjust healthcare. This preliminary work underlines the necessity of carrying out a prospective study integrating better adapted assessment tools.