Opioid versus non-opioid analgesia for spine surgery: a systematic review and meta-analysis of randomized controlled trials

Purpose Opioids are the primary analgesics used in patients undergoing spine surgery. Postoperative pain is common despite their liberal use and so are opioid-associated side effects. Non-opioid analgesics are gaining popularity as alternative to opioids in spine surgery. Methods This systematic review evaluated current evidence regarding opioid and non-opioid intraoperative analgesia and their influence on immediate postoperative pain and adverse events in spine surgery. Results A total of 10,459 records were obtained by searching Medline, EMBASE and Web of Science databases and six randomized controlled trials were included. Differences in postoperative pain scores between opioid and non-opioid groups were not significant at 1 h: 4 studies, mean difference (MD) = 0.65 units, 95% confidence intervals (CI) [-0.12 to 1.41], p = 0.10, but favored non-opioid at 24 h after surgery: 3 studies, MD = 0.75 units, 95%CI [0.03 to 1.46], p = 0.04. The time for first postoperative analgesic requirement was shorter (MD = -45.06 min, 95%CI [-72.50 to -17.62], p = 0.001), and morphine consumption during first 24 h after surgery was higher in opioid compared to non-opioid group (MD = 4.54 mg, 95%CI [3.26 to 5.82], p < 0.00001). Adverse effects of postoperative nausea and vomiting (Relative risk (RR) = 2.15, 95%CI [1.37 to 3.38], p = 0.0009) and shivering (RR = 2.52, 95%CI [1.08 to 5.89], p = 0.03) were higher and bradycardia was lower (RR = 0.35, 95%CI [0.17 to 0.71], p = 0.004) with opioid analgesia. Conclusion The certainty of evidence on GRADE assessment is low for studied outcomes. Available evidence supports intraoperative non-opioid analgesia for overall postoperative pain outcomes in spine surgery. More research is needed to find the best drug combination and dosing regimen. Prospero Registration: CRD42020209042.