Objectives
Primary objective: estimate the prevalence of POC 3 months after major abdominal surgery, describe its distribution in both opioid-naive and chronic opioid users and across different types of abdominal surgery, and estimate its association with persistent pain and quality of life.
Secondary objective: estimate the effects of individual potential risk factors on POC after major abdominal surgery.
Tertiary exploratory objective: evaluate the effect of neuraxial analgesia on POC.
Exploratory objectives: describe distribution of opioid misuse among patients with POC and the opioid consumption trajectory among preoperative chronic opioid users.
The hypotheses of the study are that:
1. POC will be high after abdominal surgeries (close to what has been reported in thoracic surgeries and pancreatectomies) and will be associated with a higher prevalence of persistent pain and lower quality of life,
2. Certain surgical and individual risk factors are determinants of POC,
3. The reduction of acute pain with neuraxial analgesia will help reduce the prevalence of postoperative POC.
4. Opioid misuse will be rare among patients with POC and most preoperative chronic opioid users with POC will not have decreased their consumption.
Design of the study: multicenter, prospective, cohort study. After obtaining consent, consecutive adult patients undergoing major open abdominal surgery will be included over a 6-month period.
Before surgery, data on planned surgery, demographics, socio-economic status, surgical and medical history, including information on preoperative opioid use and preoperative pain will be collected. For chronic opioid users, information about the reasons for opioid consumption will be recorded. Presence of co-morbidities, frailty, anxiety or depressive symptoms, catastrophizing tendency, and quality of life will be assessed using validated questionnaires.
During the hospitalization associated with the index surgery, the following data will be collected: type of anesthesia, administration of opioids or any other analgesic medication, care required following the intervention, quality of pain control, dosage of opioid consumption and presence of an opioid prescription upon discharge from hospital. The need to perform any other surgery during index hospitalization and the use of the pain transition service will be noted.
Patients will be contacted by phone three months after surgery. To quantify opioid use, a Timeline Follow Back questionnaire will be used. This questionnaire will include questions regarding opioids used, dose, frequency of use, mode of administration, reason for use, and presence of other sources of opioids, if applicable (family, unused opioids from old prescriptions). For preoperative opioid users, changes in opioid consumption will be assessed. Pharmacy-reported information regarding served opioid will be collected. The presence of complications related to opioid consumption as well as the risk of misuse will be assessed by using the Opioid Compliance Checklist. Information on hospitalizations associated with opioid-related events and on care level trajectory for up to three months after surgery will be recorded. Postoperative pain and quality of life will be assessed using validated questionnaires.
