The aim of this study is to determine the current prevalence of co-addictions, including problem/pathological gambling, in patients receiving Opiate Substitution Treatment (OST), and to then compare patients receiving OST with or without a co-addiction (excluding tobacco dependence) in order to determine their clinical profile.

In addition, an ancillary study to be carried out only among those patients receiving methadone, will aim to etablish whether a low plasma concentration of methadone, on the one hand, and an ultrarapid metabolizer genetic profile, on the other, are the characteristics most commonly associated with the presence of co-addictions. This will allow us to complete patient's pharmacological characterization.

Non-interventionel study Total duration: 12 months (preparation, recruitment, analysis) Recruitment period: 6 months Duration of monitoring per patient: no monitoring

Main objective: to assess the current prevalence of addictive co-morbidities in opiate-dependent subjects receiving Opiate Substitution Treatment (OST) for at least 6 months.

Secondary objective: to compare patients being treated using OST who currently have a co-addiction (with the exception of tobacco dependence) with patients being treated with OST who do not currently have a co-addiction, based on pharmacological and clinical characteristics (for pharmacological characteristics: pharmacokinetic and pharmacogenetic analyses as part of an ancillary study into only those patients being treated with methadone).

Main judgment criterion: Presence or absence of co-addictions (except tobacco dependence), determined using assessment tools.

The secondary assessment criteria shall be: sociodemographic data, data about opiate dependence, data about other substance use disorders, data about gambling practice, psychopathological data (impulsivity, ADHD), pharmacokinetic data and pharmacogenetic data.

Statistical analysis: For the main judgment criterion, a rate of prevalence of current co-addictions will be estimated using a 95% confidence interval.

Descriptive analyses will be carried out for all variables gathered and along with point estimates and 95% confidence intervals for qualitative and quantitative variables.

The second stage will involve univariate exploratory analyses. The two groups of patients will be compared according to the presence or absence of co-addictions. For the quantitative variables Student tests or non parametric tests will be used. For the qualitative variables, we will use Chi-squared or Fisher tests.

Finally, multivariate analyses will be carried out. The factors that have been previously identified as a being linked to co-addictions (with the threshold p = 0.2) will the be incorporated into logistic regression models. The best model, wich enables explanation of the co-addictions will then be selected using likelihood ratio tests.

General Inclusion Criteria:

• Over 18,
• Under treatment unsing methadone or buprenorhine (+/- naloxone) or morphine as substitute, prescribed for opiate dependence,
• OST begining at least 6 months previously,
• Incarceration for less than a month in the event of monitoring in SMPR,
• Good understanding of French, able to read and write.

General non-Inclusion Criteria:

• Protected adults (guardianship, wardship)
• Disorder of higher-order brains functions (severe cognitive disorders or confusion) or psychotic disorder (hallucinations, delusion) that may interfere with the study.

Non-Inclusion criteria for patients participating in the ancillary study:

• Medical monitoring by a doctor from the Drug Addiction Network of the Nantes Area,
• OST other than methadone
• Adjustement to dosage in the 5 days prior to administering OST
• Pregnant women
• Absence of social security registration.

The study deals with patients on OST precsribed to treat opiate dependence; the OST may be methadone, buprenorphine (+/- naloxone) or a morphine-based drug.

The total group of patients to be inclued is estimated at 384 patients. Of these patients, 200 will take part in the ancillary study.

The number of recruitment centers foreseen allows this objective to be met in 6 months.

Those participating in this study will not be able to participate in another study (notably in order to avoid drug interactions).