Chronic post-operative pain is generally defined by persistent pain more than 2 months after surgery. General reviews on chronic post-operative pain describe an overall incidence of 30%, of which 5 to 10% are described as severe. Different risk factors have been identified: pain and preoperative opioid use, anxiety - depression, catastrophism, type of surgery, intensity and duration of postoperative pain, genetic factors.

If postoperative pain is essentially pain caused by excess nociceptive stimulation, investigators realize that a neuropathic component is far from being exceptional and that this can be demonstrated quickly after surgery. In addition, these neuropathic pains respond little or no to the usual analgesics and in particular to opioids, which can be the cause of misuse or death from overdose. Early detection of pain of a neuropathic nature would allow appropriate therapy to be put in place and may therefore reduce the risk of chronic postoperative pain.

The concept of ambulatory surgery assumes that postoperative pain will be minimal and can be controlled at home by the administration of oral pain relievers. However, following the development of surgical techniques and the improvement in the quality of care, the number and complexity of procedures that can be performed in ambulatory surgery have increased considerably. Consequently, a significant number of patients will probably develop chronic post-operative pain without the possibility of early detection. The prevalence of chronic post-operative pain in ambulatory surgery has been studied by a single team. The authors conclude that it is underestimated and variable depending on the surgery between 15 and 32%.

For the past few years, the GHPSJ has been using an ambulatory surgery algorithm that sends SMS messages to warn and follow up on patients. The principle is simple: patients scheduled for outpatient surgery receive text messages the day before their intervention to remind them of the instructions to be followed and the meeting times and, the day after the operation, the algorithm sends SMS to ask patients if all is well or if they have pain, nausea or vomiting, discharge from the scar. In postoperative monitoring, this technology has shown promising results.

This technology has not been used in the screening of persistent pain. The objective of this work is to assess the effectiveness of an SMS algorithm in the early detection of postoperative neuropathic pain after surgery performed on an outpatient basis.

Inclusion Criteria:

• Patient aged ≥ 18 years
• Patient hospitalized on an outpatient basis within the Paris Saint Joseph Hospital Group in the following different surgical specialties: orthopedics, digestive, vascular, gynecological, plastic and restorative
• French speaking patient
• Patient with smartphone
• Patient affiliated to a social security scheme
• Patient having given oral, free, informed and express consent

Exclusion Criteria:

• Patient under guardianship or curatorship
• Patient deprived of liberty