The Pre-Operative Evaluation Clinic: An Underutilized Service in Optimizing Analgesic Outcomes in Patients on Buprenorphine, Methadone, and Naltrexone for Substance Use Disorder or Chronic Pain.

Background: Patients receiving methadone, buprenorphine, and naltrexone for either chronic pain or substance use disorder (SUD) pose perioperative challenges. Due to their complex pharmacology, perioperative recommendations continue to evolve. Deviations from these recommendations may result in worse perioperative outcomes. A formal preoperative evaluation (POE) and optimization of patients on these medications are recommended to address these concerns.

Methods: A single-center retrospective electronic health record review was performed with adult patients on methadone, buprenorphine, and naltrexone undergoing elective surgery between January 1, 2010 and December 31, 2020. The primary outcome of interest was the percentage of patients referred to the POE clinic for evaluation prior to the scheduled elective surgery. In addition, we assessed differences in variables (perioperative opioid, hospital length of stay, perioperative multimodal analgesics, perioperative complications, inpatient pain service consult, readmission within 30 days, cancellation of surgery, addiction medicine consult) based on POE clinic evaluation. This analysis was performed separately for patients prescribed these medications for SUD versus chronic pain. Continuous outcomes were analyzed using linear regression with generalized estimating equations (GEE) and robust variance estimates.

Results: A total of 714 patients were included in the final analysis, of which 572 (80%) took buprenorphine, methadone, or naltrexone for chronic pain and 142 (20%) took these medications for SUD. Within the chronic pain and SUD subpopulations, 193 (34%) and 35 (25%) patients had formal POE clinic assessments, respectively. Among those taking these medications for chronic pain, POE clinic evaluation was associated with a higher likelihood for receiving non-opioid multimodal analgesics perioperatively (p = 0.016).

Conclusion: Formal preoperative evaluations are currently underutilized in patients who take buprenorphine, methadone, or naltrexone for chronic pain or SUD. These patients may benefit from POE clinic assessment to optimize perioperative outcomes.