What is the impact of dexamethasone on postoperative pain in adults undergoing general anaesthesia for elective abdominal surgery: a systematic review and meta-analysis

BACKGROUND: Previous meta-analysis of heterogeneous surgical cohorts demonstrated reduction in postoperative pain with perioperative intravenous dexamethasone, but none have addressed adults undergoing elective abdominal surgery. The aim of this study was to determine the impact of intravenous perioperative dexamethasone on postoperative pain in adults undergoing elective abdominal surgery under general anaesthesia. METHODS: This review was prospectively registered on the international prospective register of systematic reviews (CRD42020176202). Electronic databases Medical Analysis and Retrieval System Online (MEDLINE), Exerpta Medica Database (EMBASE), (CINAHL) Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science and trial registries were searched to January 28 2021 for randomised controlled trials, comparing dexamethasone to placebo or alternative antiemetic, that reported pain. The primary outcome was pain score, and secondary outcomes were time to first analgesia, opioid requirements and time to post-anaesthesia care unit (PACU) discharge. RESULTS: Fifty-two studies (5768 participants) were included in the meta-analysis. Pain scores ≤ 4 hour (h) were reduced in patients who received dexamethasone at rest (mean difference (MD), - 0.54, 95% confidence interval (CI) - 0.72 to - 0.35, I2 = 81%) and on movement (MD - 0.42, 95% CI - 0.62 to - 0.22, I2 = 35). In the dexamethasone group, 4-24 h pain scores were less at rest (MD - 0.31, 95% CI - 0.47 to - 0.14, I2 = 96) and on movement (MD - 0.26, 95% CI - 0.39 to - 0.13, I2 = 29) and pain scores ≥ 24 h were reduced at rest (MD - 0.38, 95% CI - 0.52 to - 0.24, I2 = 88) and on movement (MD - 0.38, 95% CI - 0.65 to - 0.11, I2 = 71). Time to first analgesia (minutes) was increased (MD 22.92, 95% CI 11.09 to 34.75, I2 = 98), opioid requirements (mg oral morphine) decreased (MD - 6.66, 95% CI - 9.38 to - 3.93, I2 = 88) and no difference in time to PACU discharge (MD - 3.82, 95% CI - 10.87 to 3.23, I2 = 59%). CONCLUSIONS: Patients receiving dexamethasone had reduced pain scores, postoperative opioid requirements and longer time to first analgesia. Dexamethasone is an effective analgesic adjunct for patients undergoing abdominal surgery