To define a rational pharmacological management of pain for the subjects under opioid maintenance therapy (methadone or buprenorphine), it is first of all necessary to estimate the efficiency of the current practices on pain management as well as their potentially noxious consequences, in particular on the long term opioid maintenance therapy.

The objective of the study is to compare the efficiency of the opioid maintenance therapy according to the arisen of an acute painful phenomenon requiring an analgesic management for these patients. At first, this work will allow to determine the results on acute pain of the current practices for these patients. The comparison of the long term consequences on opioid maintenance therapy between the patients that presented an acute painful phenomenon and the control patients should help to improve acute pain management for these patients while limiting the risk of relapse in the abused consumption of psychoactive substances.

Inclusion Criteria:

• Patients aged 18 or more.
• Patients under opioid maintenance therapy (buprenorphine or methadone)
• Patients treated by the same drug (buprenorphine or methadone) since at least 3 months

Exclusion Criteria:

• Refusal of the patient to take part in the study
• Absence of possible follow-up

Patients under opioid maintenance therapy