“…All studies were retrospective (3 studies with a control group and 9 without): 4 studies examined patients with OUD taking buprenorphine, 14,24,28,30 5 examined those taking methadone, 11,[25][26][27]31 1 examined a patient taking naltrexone, 29 and 2 examined a mixed group of medications. 13,23 Four studies examined those with emergency conditions, 14, 24-26 7 examined those undergoing planned surgery, 13,23,[27][28][29][30][31] and 1 examined a mixed group of emergency and surgical patients. 11 Study size ranged from 1 to 134 participants, and studies were conducted in hospitals/tertiary care centers, specialized pain centers, and outpatient addiction treatment clinics.…”