Retrospective cohort study on the effect of intraoperative methadone on postoperative pain and opioid consumption in oral and maxillofacial surgeries

Background: Opioids are commonly used for pain control after oral and maxillofacial (OMF) surgeries, despite its potential adverse physical and social effects. There has been growing evidence that intraoperative methadone helps reduce postoperative pain and opioid consumption in various surgeries. However, it has not yet been studied in OMF surgeries. Methods: Following the Partners Human Research Committee approval, a retrospective cohort study identified 185 patients who had OMF surgeries longer than 4 hours between June 30, 2016 to July 1, 2022. Among them, 17 patients were exposed to intraoperative methadone (5–10 mg); 168 patients were identified as the control subjects. The postoperative pain score and opioid consumption in morphine milligram equivalent (MME) in post anesthesia care unit (PACU), 6 hours after surgery and 12 hours after surgery were compared. Results: The median [interquartile range (IQR)] pain score for methadone group (M group) in PACU, first 6 hours postoperatively and first 12 hours postoperatively were 0.00 (0.00, 5.50), 2.00 (0.00, 4.50), 2.00 (1.50, 4.50); and those for routine group (R group) were 5.00 (2.00, 7.00), 5.00 (3.00, 6.50), 5.00 (3.00, 6.12) respectively. There were statistically significant differences between the pain scores of M group and R group at all three time points (P=0.045, 0.024 and 0.024). After multivariable analysis, the differences remained statistically significant. The total MME (IQR) for M group in PACU, first 6 hours postoperatively and first 12 hours postoperatively were 4.51 (2.52, 7.70), 4.36 (3.35, 9.86), 6.75 (4.50, 9.86); those for R group were 5.03 (3.02, 10.03), 5.60 (3.76, 10.48), 8.85 (4.75, 14.00). There was no statistically significant difference between the two groups at any of the three time points (P=0.527, 0.557, 0.396). No adverse reactions related to opioids were reported in the M group. Time to discharge from PACU was comparable between the two groups (2.33 and 2.47 hours, P=0.664). Conclusions: a single dose of intraoperative methadone improves postoperative pain after OMF surgeries but does not reduce postoperative opioid consumption. Future comprehensive large-scale studies are needed to validate the safety and efficacy of methadone use in different surgical populations.