To compare post-operative opioid analgesic requirements for pregnant women with opioid use disorder maintained on opioid agonist treatment (OAT), methadone or buprenorphine, and delivered by cesarean section.METHODS:
This was a retrospective review of women on methadone or buprenorphine who underwent a cesarean section from 2006–2010. Antepartum OAT was continued unchanged for both the methadone and buprenorphine groups during the peri-operative period. Pre-operative, intraoperative and postoperative opioid requirements (morphine equivalent dose [MED]) were compared between the methadone and buprenorphine groups.RESULTS:
There were 140 women on methadone [mean dose 93.7 mg, SD 43.2] and 55 women on buprenorphine [mean dose 16.1 mg, SD 8.6] in the cohort. Thirty six percent in the buprenorphine group versus 33% in the methadone group [mean difference (MD) 1.1, 95% CI 0.7–1.7] had elective repeat cesareans. Fewer women in the buprenorphine group had spinal anesthesia (49% vs 70%, MD 0.7, 95% CI 0.5–0.9). There were no differences in MED intraoperatively. Those in the buprenorphine group required less pre-operative MED [20.4 mg (SD 1.5.8) vs 210.6 mg (SD 586.5 mg), MD −190.2 (95% CI −425.1 to −44.7)] and less MED in the first 24 hours postpartum (246.5 mg [SD 615.3] vs 501.2 mg [SD 219.8], MD −254.7 mg [95% CI −374.6 to −134.8]). There were no differences in postoperative complications between the two groups or length of hospitalization.CONCLUSION:
Women with opioid use disorder maintained on buprenorphine had lower opioid requirements post-partum than those on methadone. This has important implications for the management of those with opioid use disorders surrounding surgical procedures.