Maine Medical Center, Medical Education, Maine Medical Center Research Institute, Obstetrics & Gynecology, Anesthesiology & Pain Management
Humans, Pregnancy, Female, Cesarean Section, Retrospective Studies, Pain, Postoperative, Acute Pain
Background: Opioid agonist pharmacotherapy, most commonly methadone or buprenorphine, is strongly recommended for patients with opioid use disorder during pregnancy and peripartum to reduce the risk of relapse and obstetric complications. Patients on opioid agonist pharmacotherapy can have difficulty achieving adequate pain relief following cesarean section and often require higher doses of opioids; however small retrospective studies have been conflicting.
Methods: We generated a comprehensive dataset of all patients who underwent cesarean section at our institution between January 2016 and December 2018. We compared 24 hour postoperative opioid consumption for patients receiving methadone or buprenorphine at the time of surgery with data from patients who were not receiving opioid agonist pharmacotherapy. Postoperative doses of methadone and buprenorphine were excluded. Secondary outcomes were highest pain score in the first 24 hours after surgery and length of stay after surgery. Data were compared between subgroups using nonparametric methods, with subsequent adjustment for covariates by ANCOVA or ordinal logistic regression, as appropriate.
Results: Median opioid consumption during the first 24 hours after surgery was over three times higher for patients taking methadone or buprenorphine (median [interquartile range]: 105 [69.5-120] MME and 97.5 [75-120] MME, respectively, compared with 30 [0-64] MME among women not taking opioid agonists, p<0.001). Highest pain scores observed during the first 24 hours after surgery were also higher for patients taking methadone or buprenorphine (mean (standard deviation): 8.3 (1.5) and 8.2 (1.6), respectively, compared with 5.5 (2.2), p<0.001). These differences remained significant after adjustment for covariates (maternal age, smoking and marital status, parity, use of intrathecal morphine, chronic pain, hypertension, and mental health comorbidity). Length of stay after surgery was also higher for patients taking methadone or buprenorphine (median [interquartile range]: 72 [68-79.5] and 73 [69-77] hours, respectively, compared with 71 [62-76] hours, p=0.002). Again, this difference remained significant after adjustment for covariates (parity, gestation type, marital status, race, the use of intrathecal morphine, depression, hypertension, and renal insufficiency). There were no differences in the above outcome variables between the buprenorphine and methadone groups.
Conclusions: Our results support a strong relationship between opioid agonist pharmacotherapy and increased post cesarean section pain. In light of the current opioid epidemic, further studies are urgently needed to investigate and identify improved pain management strategies in this patient population.
Cobb, Johanna; Snow, Elizabeth; Turcotte, Heather; Quaye, Aurora; Craig, Wendy; and Warters, Robert, "A Retrospective Study of Acute Post-Operative Pain Following Cesarean Section in Patients on Opioid Agonist Pharmacotherapy" (2020). Costas T. Lambrew Research Retreat 2020. 40.